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Open Field (open + field)
Terms modified by Open Field Selected AbstractsApoptotic and behavioral sequelae of mild brain trauma in miceJOURNAL OF NEUROSCIENCE RESEARCH, Issue 4 2007David Tweedie Abstract Mild traumatic brain injury (mTBI) is a not uncommon event in adolescents and young adults. Although it does not result in clear morphological brain defects, it is associated with long-term cognitive, emotional, and behavioral problems. Herein, we characterized the biochemical and behavioral changes associated with experimental mTBI in mice that may act as either targets or surrogate markers for interventional therapy. Specifically, mTBI was induced by 30-g and 50-g weight drop, and at 8 and 72 hr thereafter markers of cellular apoptosis,caspase-3, Bax, apoptosis-inducing factor (AIF), and cytochrome-c (Cyt-c),were quantified by Western blot analysis in hippocampus ipsilateral to the impact. Levels of amyloid-, precursor protein (APP) were also measured, and specific behavioral tests,passive avoidance, open field, and forced swimming (Porsolt) paradigms,were undertaken to assess learning, emotionality, and emotional memory. In the absence of hemorrhage or infarcts, as assessed by triphenyltetrazolium chloride staining, procaspase-3 and Bax levels were markedly altered following mTBI at both times. No cleaved caspase-3 was detected, and levels of AIF and Cyt-c, but not APP, were significantly changed at 72 hr. Mice subjected to mTBI were indistinguishable from controls by neurological examination at 1 and 24 hr, and by passive avoidance/open field at 72 hr, but could be differentiated in the forced swimming paradigm. In general, this model mimics the diffuse effects of mTBI on brain function associated with the human condition and highlights specific apoptotic proteins and a behavioral paradigm as potential markers for prospective interventional strategies. © 2007 Wiley-Liss, Inc. [source] Artificial rearing alters the response of rats to natural and drug-mediated rewardsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2006Anna M. Lomanowska Abstract Artificial rearing (AR) of infant rats permits precise control over key features of the early environment without maternal influence. The present study examined the behavioral response of AR rats towards natural and drug-mediated rewards, as well as their exploratory and affective behaviors. Adolescent AR rats showed increased preference for sucrose consumption relative to chow and demonstrated greater activity in the open field and in the elevated plus-maze compared to maternally reared (MR) rats. With respect to measures of emotionality, AR rats showed enhanced avoidance of the open arms of the plus-maze, indicating increased anxiety, but they did not differ from MR rats in exploring the center of the open field. Adult AR rats displayed a stronger conditioned response to morphine in a place preference test. These findings support the potential of the AR model to contribute to understanding the role of early experience in the development of behavioral motivation. © 2006 Wiley Periodicals, Inc. Dev Psyshobiol 48: 301,314, 2006. [source] Influence of parental deprivation on the behavioral development in Octodon degus: Modulation by maternal vocalizationsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2003Katharina Braun Abstract Repeated separation from the family during very early stages of life is a stressful emotional experience which induces a variety of neuronal and synaptic changes in limbic cortical areas that may be related to behavioral alterations. First, we investigated whether repeated parental separation and handling, without separation from the family, leads to altered spontaneous exploratory behavior in a novel environment (open field test) in 8-day-old Octodon degus. Second, we tested whether the parentally deprived and handled animals display different stimulus-evoked exploratory behaviors in a modified open field version, in which a positive emotional stimulus, the maternal call, was presented. In the open field test a significant influence of previous emotional experience was found for the parameters of running, rearing, and vocalization. Parentally deprived degus displayed increased horizontal (running) and vertical (rearing) motoric activities, but decreased vocalization, compared to normal and handled controls. The presentation of maternal vocalizations significantly modified running, vocalization, and grooming activities, which in the case of running activity was dependent on previous emotional experience. Both deprivation-induced locomotor hyperactivity together with the reduced behavioral response towards a familiar acoustic emotional signal are similar to behavioral disturbances observed in human attachment disorders. © 2003 Wiley Periodicals, Inc. Dev Psychobiol 42: 237,245, 2003. [source] Effects of neonatal handling and maternal separation on rough-and-tumble play in the ratDEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2002Jennifer L. Arnold Abstract The extent to which brief daily handling and longer periods of separation from the mother during the first 2 weeks of life can affect play behavior in juvenile rats was assessed. Rat pups were separated from the mother for either 15 min daily (handling) or for 3 hr daily (maternal separation), and play was observed as juveniles. Overall levels of playfulness were not affected by either manipulation, although certain aspects of playful responsiveness were affected in males, but not females. In particular, the pattern of responsiveness to playful contacts was feminized in both handled and separated male rats. Activity in a novel open field at 15 days of age was increased in both males and females from the separated group, but not in the handled animals, as were the number of rears exhibited during the play bouts. These data suggest that early rearing experiences can have subtle gender-dependent effects on some aspects of play in juvenile rats and that the underlying mechanism(s) responsible for these effects may differ from those associated with other effects reported for handling and maternal separation. © 2002 Wiley Periodicals, Inc. Dev Psychobiol 41: 205,215, 2002. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/dev.10069 [source] Toxicity and chemistry of aspen wood leachate to aquatic life: Field studyENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2003Barry R. Taylor Abstract A dark, toxic leachate has been observed around woodpiles of trembling aspen (Populus tremuloides Michx.) cut in winter for pulp or structural lumber. We measured production of leachate from 18 m3 of harvestable aspen logs stacked in an open field near Dawson Creek, British Columbia, Canada. The logpile began producing leachate during the first winter thaw and continued to do so for the duration of the two-year study (mean, 250 L/collection). Aspen leachate was characterized by dark color, acidic pH (5.0-6.5), elevated conductivity (200-500 ,S/cm), high to very high biochemical oxygen demand (500-5,000 mg/L) and total organic carbon concentrations (500-2,000 mg/L), variable levels of phenolic compounds (2-27 mg/L), and low dissolved oxygen tensions (<2 mg/L). In tests with rainbow trout (Oncorhynchus mykiss), Daphnia magna, and luminescent bacteria, the leachate varied from weakly toxic (median lethal concentration, >10%) to very toxic (median lethal concentration, <1%). The volume of leachate generated by the logpile was correlated with total precipitation (rain or snow) since the last collection. Loads of chemical constituents or toxicity (lethal concentration × volume) in the leachate did not decline over the duration of the study. Less than 10% of the total mass of leachable material in the aspen logs was removed during two years of exposure. [source] Predictors of pharmacoresistant epilepsy: Pharmacoresistant rats differ from pharmacoresponsive rats in behavioral and cognitive abnormalities associated with experimentally induced epilepsyEPILEPSIA, Issue 10 2008Alexandra M. Gastens Summary Purpose:, Patients with intractable temporal lobe epilepsy (TLE) exhibit an increased risk of psychiatric comorbidity, including depression, anxiety, psychosis, and learning disorders. Furthermore, a history of psychiatric comorbidity has been suggested as a predictor of lack of response to therapy with antiepileptic drugs (AEDs) in patients with epilepsy. However, clinical studies on predictors of pharmacoresistant epilepsy are affected by several confounding variables, which may complicate conclusions. In the present study, we evaluated whether behavioral alterations in epileptic rats are different in AED nonresponders versus responders. Methods:, For this purpose, we used an animal model of TLE in which AED responders and nonresponders can be selected by prolonged treatment of epileptic rats with phenobarbital (PB). Behavioral and cognitive abnormalities were compared between responders and nonresponders as well as between epileptic rats and nonepileptic controls in a battery of tests. Results:, Fifteen epileptic rats with spontaneous recurrent seizures (SRS) either responding (11 rats) or not responding (4 rats) to PB were used for this study. The nonresponders differed markedly in behavioral and cognitive abnormalities from responders and nonepileptic controls in tests of anxiety (open field, elevated-plus maze test), behavioral hyperexcitability (approach-response, touch-response, pick-up tests), and learning and memory (Morris water maze). Discussion:, Our hypothesis that AED-resistant rats will show more severe behavioral and cognitive changes than AED-responsive rats was confirmed by the present experiments. The data substantiate that rodent models of TLE are useful to delineate predictors of pharmacoresistant epilepsy. [source] Mice with astrocyte-directed inactivation of connexin43 exhibit increased exploratory behaviour, impaired motor capacities, and changes in brain acetylcholine levelsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2003Christian Frisch Abstract Gap junctions mediate communication between many cell types in the brain. Gap junction channels are composed of membrane-spanning connexin (Cx) proteins, allowing the cell-to-cell passage of small ions and metabolites. Cx43 is the main constituent of the brain-spanning astrocytic gap junctional network, controlling activity-related changes in ion and glutamate concentrations as well as metabolic processes. In astrocytes, deletion of Cx43-coding DNA led to attenuated gap junctional coupling and impaired propagation of calcium waves, known to influence neuronal activity. Investigation of the role of Cx43 in behaviour has been impossible so far, due to postnatal lethality of its general deletion. Recently, we have shown that deletion of Cx30, which is also expressed by astrocytes, affects exploration, emotionality, and neurochemistry in the mouse. In the present study, we investigated the effects of the astrocyte-directed inactivation of Cx43 on mouse behaviour and brain neurochemistry. Deletion of Cx43 in astrocytes increased exploratory activity without influencing habituation. In the open field, but not in the elevated plus-maze, an anxiolytic-like effect was observed. Rotarod performance was initially impaired, but reached control level after further training. In the water maze, Cx43 deficient mice showed a steeper learning course, although final performance was similar between groups. Cx43 inactivation in astrocytes increased acetylcholine content in the frontal cortex of water maze-trained animals. Results are discussed in terms of altered communication between astrocytes and neurons, possible compensation processes, and differential effects of Cx30- and astrocyte-specific Cx43 deletion. [source] Sexual dimorphism in the spontaneous recovery from spinal cord injury: a gender gap in beneficial autoimmunity?EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2002Ehud Hauben Abstract Immune cells have been shown to contribute to spontaneous recovery from central nervous system (CNS) injury. Here we show that adult female rats and mice recover significantly better than their male littermates from incomplete spinal cord injury (ISCI). This sexual dimorphism is wiped out and recovery is worse in adult mice deprived of mature T cells. After spinal cord contusion in adult rats, functional recovery (measured by locomotor scores in an open field) was significantly worse in females treated with dihydrotestosterone prior to the injury than in placebo-treated controls, and significantly better in castrated males than in their noncastrated male littermates. Post-traumatic administration of the testosterone receptor antagonist flutamide promoted the functional recovery in adult male rats. These results, in line with the known inhibitory effect of testosterone on cell-mediated immunity, suggest that androgen-mediated immunosuppression plays a role in ISCI-related immune dysfunction and can therefore partly explain the worse outcome of ISCI in males than in female. We suggest that females, which are more prone to develop autoimmune response than males, benefit from this response in cases of CNS insults. [source] Hyperactivity, startle reactivity and cell-proliferation deficits are resistant to chronic lithium treatment in adult Nr2e1frc/frc miceGENES, BRAIN AND BEHAVIOR, Issue 7 2010B. K. Y. Wong The NR2E1 region on Chromosome 6q21-22 has been repeatedly linked to bipolar disorder (BP) and NR2E1 has been associated with BP, and more specifically bipolar I disorder (BPI). In addition, patient sequencing has shown an enrichment of rare candidate-regulatory variants. Interestingly, mice carrying either spontaneous (Nr2e1frc) or targeted (Tlx,) deletions of Nr2e1 (here collectively known as Nr2e1 -null) show similar neurological and behavioral anomalies, including hypoplasia of the cerebrum, reduced neural stem cell proliferation, extreme aggression and deficits in fear conditioning; these are the traits that have been observed in some patients with BP. Thus, NR2E1 is a positional and functional candidate for a role in BP. However, no Nr2e1 -null mice have been fully evaluated for behaviors used to model BP in rodents or pharmacological responses to drugs effective in treating BP symptoms. In this study we examine Nr2e1frc/frc mice, homozygous for the spontaneous deletion, for abnormalities in activity, learning and information processing, and cell proliferation; these are the phenotypes that are either affected in patients with BP or commonly assessed in rodent models of BP. The effect of lithium, a drug used to treat BP, was also evaluated for its ability to attenuate Nr2e1frc/frc behavioral and neural stem cell-proliferation phenotypes. We show for the first time that Nr2e1 -null mice exhibit extreme hyperactivity in the open field as early as postnatal day 18 and in the home cage, deficits in open-field habituation and passive avoidance, and surprisingly, an absence of acoustic startle. We observed a reduction in neural stem/progenitor cell proliferation in Nr2e1frc/frc mice, similar to that seen in other Nr2e1 -null strains. These behavioral and cell-proliferation phenotypes were resistant to chronic-adult-lithium treatment. Thus, Nr2e1frc/frc mice exhibit behavioral traits used to model BP in rodents, but our results do not support Nr2e1frc/frc mice as pharmacological models for BP. [source] Enhanced dopamine function in DISC1-L100P mutant mice: implications for schizophreniaGENES, BRAIN AND BEHAVIOR, Issue 7 2010T. V. Lipina Significant advances have been made in understanding the role of disrupted-in-schizophrenia-1 (DISC1) in the brain and accumulating findings suggest the possible implication of DISC1 in the regulation of dopamine (DA) function. A mutation in the second exon of DISC1 at L100P leads to the development of schizophrenia-related behavior in mutant mice (DISC1-L100P). We investigated here the role of DA in the expression of schizophrenia-related endophenotypes in the DISC1-L100P genetic mouse model. The mutated DISC1 resulted in facilitation of the psychostimulant effect of amphetamine in DISC1-L100P mutant mice assessed in the open field and prepulse inhibition (PPI) tests. Biochemical studies detected a 2.1-fold increase in the proportion of striatal Dreceptors without significant changes in DA release in vivo in the striatum of DISC1-L100P mutants in response to the low dose of amphetamine. The D2 receptor antagonist haloperidol reversed the hyperactivity, PPI and latent inhibition (LI) deficits and blocked the psychostimulant effect of amphetamine in DISC1-L100P mutants. Taken together, our findings show the role of DISC1 in D2 -related pathophysiological mechanism of schizophrenia, linking DISC1 with well-established DA hypothesis of schizophrenia. [source] Male and female Fmr1 knockout mice on C57 albino background exhibit spatial learning and memory impairmentsGENES, BRAIN AND BEHAVIOR, Issue 6 2010K. B. Baker Impaired spatial learning is a prominent deficit in fragile X syndrome (FXS). Previous studies using the Fmr1 knockout (KO) mouse model of FXS have not consistently reported a deficit in spatial learning. Fmr1 KO mice bred onto an albino C57BL/6J- Tyrc-Brd background showed significant deficits in several primary measures of performance during place navigation and probe trials in the Morris water maze. Fmr1 KO mice were also impaired during a serial reversal version of the water maze task. We examined fear conditioning as an additional cognitive screen. Knockout mice exhibited contextual memory deficits when trained with unsignaled shocks; however, deficits were not found in a separate group of KO mice trained with signaled shocks. No potentially confounding genotypic differences in locomotor activity were observed. A decreased anxiety-like profile was apparent in the open field, as others have noted, and also in the platform test. Also as previously reported, startle reactivity to loud auditory stimuli was decreased, prepulse inhibition and social interaction increased in KO mice. Female Fmr1 KO mice were tested along with male KO mice in all assays, except for social interaction. The female and male KO exhibited very similar impairments indicating that sex does not generally drive the behavioral symptoms of the disorder. Our results suggest that procedural factors, such as the use of albino mice, may help to reliably detect spatial learning and memory impairments in both sexes of Fmr1 KO mice, making it more useful for understanding FXS and a platform for evaluating potential therapeutics. [source] Postnatal handling reverses social anxiety in serotonin receptor 1A knockout miceGENES, BRAIN AND BEHAVIOR, Issue 1 2010C. Zanettini Mice lacking the serotonin receptor 1A (Htr1a knockout, Htr1aKO) show increased innate and conditioned anxiety. This phenotype depends on functional receptor activity during the third through fifth weeks of life and thus appears to be the result of long-term changes in brain function as a consequence of an early deficit in serotonin signaling. To evaluate whether this phenotype can be influenced by early environmental factors, we subjected Htr1a knockout mice to postnatal handling, a procedure known to reduce anxiety-like behavior and stress responses in adulthood. Offspring of heterozygous Htr1a knockout mice were separated from their mother and exposed 15 min each day from postnatal day 1 (PD1) to PD14 to clean bedding. Control animals were left undisturbed. Maternal behavior was observed during the first 13 days of life. Adult male offspring were tested in the open field, social approach and resident,intruder tests and assessed for corticosterone response to restraint stress. Knockout mice showed increased anxiety in the open field and in the social approach test as well as an enhanced corticosterone response to stress. However, while no effect of postnatal handling was seen in wild-type mice, handling reduced anxiety-like behavior in the social interaction test and the corticosterone response to stress in knockout mice. These findings extend the anxiety phenotype of Htr1aKO mice to include social anxiety and demonstrate that this phenotype can be moderated by early environmental factors. [source] Neurobehavioral abnormalities in the dysbindin-1 mutant, sandy, on a C57BL/6J genetic backgroundGENES, BRAIN AND BEHAVIOR, Issue 4 2009M. M. Cox Sandy mice have a deletion mutation in the gene encoding dysbindin-1, Dtnbp1, with consequent reduction of the protein in heterozygotes and its loss in homozygotes. The sandy mouse thus serves as an animal model of dysbindin-1 function. As this protein is concentrated in synaptic tissue and affects transmitter release, it may affect neuronal processes that mediate behavior. To investigate the neurobehavioral effects of the Dtnbp1 mutation, we studied littermate sandy and wild-type controls on a C57BL/6J genetic background. The three animal groups were indistinguishable in their external physical characteristics, sensorimotor skills and indices of anxiety-like behaviors. In the open field, however, homozygous animals were hyperactive and appeared to show less habituation to the initially novel environment. In the Morris water maze, homozygous animals displayed clear deficits in spatial learning and memory with marginal deficits in visual association learning. Apart from the last mentioned deficits, these abnormalities are consistent with hippocampal dysfunction and in some cases with elevated dopaminergic transmission via D2 dopamine receptors. As similar deficits in spatial learning and memory have been found in schizophrenia, where decreased dysbindin-1 has been found in the hippocampus, the sandy mouse may also model certain aspects of cognition and behavior relevant to schizophrenia. [source] Increased fear- and stress-related anxiety-like behavior in mice lacking tuberoinfundibular peptide of 39 residuesGENES, BRAIN AND BEHAVIOR, Issue 8 2008D. B. Fegley Tuberoinfundibular peptide of 39 residues (TIP39) is synthesized by two groups of neurons, one in the subparafascicular area at the caudal end of the thalamus and the other in the medial paralemniscal nucleus within the lateral brainstem. The subparafascicular TIP39 neurons project to a number of brain regions involved in emotional responses, and these regions contain a matching distribution of a receptor for TIP39, the parathyroid hormone 2 receptor (PTH2-R). We have now evaluated the involvement of TIP39 in anxiety-related behaviors using mice with targeted null mutation of the TIP39 gene (Tifp39). Tifp39,/, mice (TIP39-KO) did not significantly differ from wild-type (WT) littermates in the open field, light/dark exploration and elevated plus-maze assays under standard test conditions. However, the TIP39-KO engaged in more active defensive burying in the shock-probe test. In addition, when tested under high illumination or after restraint, TIP39-KO displayed significantly greater anxiety-like behavior in the elevated plus-maze than WT. In a Pavlovian fear-conditioning paradigm, TIP39-KO froze more than WT during training and during tone and context recall but showed normal fear extinction. Disruption of TIP39 projections to the medial prefrontal cortex, lateral septum, bed nucleus of the stria terminalis, hypothalamus and amygdala likely account for the fear- and anxiety-related phenotype of TIP39-KO. Current data support the hypothesis that TIP39 modulates anxiety-related behaviors following environmental provocation. [source] Neuronal cell adhesion molecule deletion induces a cognitive and behavioral phenotype reflective of impulsivityGENES, BRAIN AND BEHAVIOR, Issue 4 2008L. D. Matzel Cell adhesion molecules, such as neuronal cell adhesion molecule (Nr-CAM), mediate cell,cell interactions in both the developing and mature nervous system. Neuronal cell adhesion molecule is believed to play a critical role in cell adhesion and migration, axonal growth, guidance, target recognition and synapse formation. Here, wild-type, heterozygous and Nr-CAM null mice were assessed on a battery of five learning tasks (Lashley maze, odor discrimination, passive avoidance, spatial water maze and fear conditioning) previously developed to characterize the general learning abilities of laboratory mice. Additionally, all animals were tested on 10 measures of sensory/motor function, emotionality and stress reactivity. We report that the Nr-CAM deletion had no impact on four of the learning tasks (fear conditioning, spatial water maze, Lashley maze and odor discrimination). However, Nr-CAM null mice exhibited impaired performance on a task that required animals to suppress movement (passive avoidance). Although Nr-CAM mutants expressed normal levels of general activity and body weights, they did exhibit an increased propensity to enter stressful areas of novel environments (the center of an open field and the lighted side of a dark/light box), exhibited higher sensitivity to pain (hot plate) and were more sensitive to the aversive effects of foot shock (shock-induced freezing). This behavioral phenotype suggests that Nr-CAM does not play a central role in the regulation of general cognitive abilities but may have a critical function in regulating impulsivity and possibly an animal's susceptibility to drug abuse and addiction. [source] The type 1 equilibrative nucleoside transporter regulates anxiety-like behavior in miceGENES, BRAIN AND BEHAVIOR, Issue 8 2007J. Chen Activation of adenosine receptors in the brain reduces anxiety-like behavior in animals and humans. Because nucleoside transporters regulate adenosine levels, we used mice lacking the type 1 equilibrative nucleoside transporter (ENT1) to investigate whether ENT1 contributes to anxiety-like behavior. The ENT1 null mice spent more time in the center of an open field compared with wild-type littermates. In the elevated plus maze, ENT1 null mice entered more frequently into and spent more time exploring the open arms. The ENT1 null mice also spent more time exploring the light side of a light,dark box compared with wild-type mice. Microinjection of an ENT1-specific antagonist, nitrobenzylthioinosine (nitrobenzylmercaptopurine riboside), into the amygdala of C57BL/6J mice reduced anxiety-like behavior in the open field and elevated plus maze. These findings show that amygdala ENT1 modulates anxiety-like behavior. The ENT1 may be a drug target for the treatment of anxiety disorders. [source] Altered behavioural adaptation in mice with neural corticotrophin-releasing factor overexpressionGENES, BRAIN AND BEHAVIOR, Issue 7 2007M. Kasahara Overproduction of corticotrophin-releasing factor (CRF), the major mediator of the stress response, has been linked to anxiety, depression and addiction. CRF excess results in increased arousal, anxiety and altered cognition in rodents. The ability to adapt to a potentially threatening stimulus is crucial for survival, and impaired adaptation may underlie stress-related psychiatric disorders. Therefore, we examined the effects of chronic transgenic neural CRF overproduction on behavioural adaptation to repeated exposure to a non-home cage environment. We report that CRF transgenic mice show impaired adaptation in locomotor response to the novel open field. In contrast to wild-type (WT) mice, anxiety-related behaviour of CRF transgenic mice does not change during repeated exposure to the same environment over the period of 7 days or at retest 1 week later. We found that locomotor response to novelty correlates significantly with total locomotor activity and activity in the centre at the last day of testing and at retest in WT but not in CRF transgenic mice. Mice were divided into low responders and high responders on the basis of their initial locomotor response to novelty. We found that differences in habituation and re-exposure response are related to individual differences in locomotor response to novelty. In summary, these results show that CRF transgenic mice are fundamentally different from WT in their ability to adapt to an environmental stressor. This may be related to individual differences in stress reactivity. These findings have implications for our understanding of the role of CRF overproduction in behavioural maladaptation and stress-related psychiatric disorders. [source] Deficits in acetylcholine homeostasis, receptors and behaviors in choline transporter heterozygous miceGENES, BRAIN AND BEHAVIOR, Issue 5 2007M. H. Bazalakova Cholinergic neurons elaborate a hemicholinium-3 (HC-3) sensitive choline transporter (CHT) that mediates presynaptic, high-affinity choline uptake (HACU) in support of acetylcholine (ACh) synthesis and release. Homozygous deletion of CHT (,/,) is lethal shortly after birth (Ferguson et al. 2004), consistent with CHT as an essential component of cholinergic signaling, but precluding functional analyses of CHT contributions in adult animals. In contrast, CHT+/, mice are viable, fertile and display normal levels of synaptosomal HACU, yet demonstrate reduced CHT protein and increased sensitivity to HC-3, suggestive of underlying cholinergic hypofunction. We find that CHT+/, mice are equivalent to CHT+/+ siblings on measures of motor co-ordination (rotarod), general activity (open field), anxiety (elevated plus maze, light/dark paradigms) and spatial learning and memory (Morris water maze). However, CHT+/, mice display impaired performance as a result of physical challenge in the treadmill paradigm, as well as reduced sensitivity to challenge with the muscarinic receptor antagonist scopolamine in the open field paradigm. These behavioral alterations are accompanied by significantly reduced brain ACh levels, elevated choline levels and brain region-specific decreased expression of M1 and M2 muscarinic acetylcholine receptors. Our studies suggest that CHT hemizygosity results in adequate baseline ACh stores, sufficient to sustain many phenotypes, but normal sensitivities to physical and/or pharmacological challenge require full cholinergic signaling capacity. [source] Evidence for a female-specific effect of a chromosome 4 locus on anxiety-related behaviors and ethanol drinking in ratsGENES, BRAIN AND BEHAVIOR, Issue 6 2006L. F. Vendruscolo Previous studies using the inbred rat strains Lewis (LEW) and spontaneously hypertensive rats (SHR) led to the mapping of two quantitative trait loci, named Ofil1 (on chromosome 4 of the rat) and Ofil2 (on chromosome 7), for open-field inner locomotion, a behavioral index of anxiety. Studies using other strains showed that the region next to Ofil1 influences measures of not only anxiety but also ethanol consumption. In view of the high prevalence of psychiatric disorders such as anxiety and alcoholism, as well as the comorbidity between them, the present study was designed to better characterize the contribution of these two loci to complex emotional and consummatory responses. Rats deriving from an F2 intercross between the LEW and the SHR strains were selected according to their genotype at markers flanking the loci Ofil1 and Ofil2 and bred to obtain lines of rats homozygous LEW/LEW or SHR/SHR for each of the two loci, thus generating four genotypic combinations. These selected animals as well as purebred LEW and SHR rats of both sexes were submitted to a battery of tests including measures of locomotor activity, anxiety, sweet and bitter taste reinforcement and ethanol intake. Lewis rats displayed more anxiety-like behavior and less ethanol intake than SHR rats. Ofil1 (on chromosome 4) affected both the activity in the center of the open field and ethanol drinking in females only. These results suggest that Ofil1 contains either linked genes with independent influences on anxiety-related responses and ethanol drinking or a pleiotropic gene with simultaneous effects on both traits. [source] Impaired spatial reference memory and increased exploratory behavior in P301L tau transgenic miceGENES, BRAIN AND BEHAVIOR, Issue 5 2006L. Pennanen The neuropathological hallmark shared between Alzheimer's disease (AD) and familial frontotemporal dementia (FTDP-17) are neurofibrillary tangles (NFT) which are composed of filamentous aggregates of the microtubule-associated protein tau. Their formation has been reproduced in transgenic mice, which express the FTDP-17-associated mutation P301L of tau. In these mice, tau aggregates are found in many brain areas including the hippocampus and the amygdala, both of which are characterized by NFT formation in AD. Previous studies using an amygdala-specific test battery revealed an increase in exploratory behavior and an accelerated extinction of conditioned taste aversion in these mice. Here, we assessed P301L mice in behavioral tests known to depend on an intact hippocampus. Morris water maze and Y-maze revealed intact spatial working memory but impairment in spatial reference memory at 6 and 11 months of age. In addition, a modest disinhibition of exploratory behavior at 6 months of age was confirmed in the open field and the elevated O-maze and was more pronounced during aging. [source] Common variations in the pretest environment influence genotypic comparisons in models of anxietyGENES, BRAIN AND BEHAVIOR, Issue 7 2005G. S. Izídio The behavioral characterization of rodent strains in different studies and laboratories can provide unreplicable results even when genotypes are kept constant and environmental control is maximized. In the present study, the influence of common laboratory environmental variables and their interaction with genotype on the results of behavioral tests of anxiety/emotionality were investigated. To this end, the inbred rat strains Lewis (LEW) and spontaneously hypertensive rats (SHR), which are known to differ for numerous emotionality-related behaviors, were tested in the open field (OF), elevated plus maze (EPM) and black/white box (BWB), while three environmental factors were systematically controlled and analyzed: (1) the experimenter handling the animal (familiar or unfamiliar); (2) the position of the home cage (top or bottom shelf of the rack) and (3) the behavioral state of the animal immediately before the test (arousal or rest). Experimenter familiarity did not alter the behavior of rats in the OF. Cage position, on the other hand, influenced the behavior in the OF and BWB, with rats housed in top cages appearing less anxious like than those housed in the bottom. In the BWB (but not in the OF), these effects were genotype dependent. Finally, the behavioral state of the animals prior to testing altered the results of the EPM in a strain-dependent manner, with some anxiety-related genotypic differences being found only among rats that were aroused in their home cages. This study showed that common variations in the laboratory environment interact with genotype in behavioral tests of anxiety/emotionality. Recognizing and understanding such variations can help in the design of more effective experiments. [source] Pleiotropic effect of a locus on chromosome 4 influencing alcohol drinking and emotional reactivity in ratsGENES, BRAIN AND BEHAVIOR, Issue 3 2003E. Terenina-Rigaldie A QTL search in a segregating F2 intercross between HEP (High-Ethanol Preferring line) and wistar-kyoto (WKY, a low-alcohol consuming strain) rats identified a locus on chromosome 4 linked to the consumption of a 5% alcohol solution offered as a free choice with water (Terenina-Rigaldie et al. submitted). In order to confirm and analyse the influence of this locus, F2 rats were selected according to their genotype at the markers flanking the QTL and bred in order to obtain two groups of rats homozygous HEP/HEP (,HIGH' line) or WKY/WKY (,LOW' line) at the QTL, the rest of the genome being randomly inherited from one or the other founder strain. These two groups of animals displayed large differences in emotional reactivity (open field, elevated-plus maze), sensitivity to taste reinforcers (saccharin, quinine) and alcohol consumption (either forced or as a free choice with water). These results confirm the influence of this locus on alcohol intake and emotional reactivity traits, and suggest a pleiotropic effect of the gene(s) involved. Current research aims at the identification of this (these) gene(s). [source] Spatial firing properties of lateral septal neuronsHIPPOCAMPUS, Issue 8 2006Yusaku Takamura Abstract The present study describes the spatial firing properties of neurons in the lateral septum (LS). LS neuronal activity was recorded in rats as they performed a spatial navigation task in an open field. In this task, the rat acquired an intracranial self-stimulation reward when it entered a certain place, a location that varied randomly from trial to trial. Of 193 neurons recorded in the LS, 81 showed place-related activity. The majority of the tested neurons changed place-related activity when spatial relations between environmental cues were altered by rotating intrafield (proximal) cues. The comparison of place activities between LS place-related neurons recorded in the present study and hippocampal place cells recorded in our previous study, using identical behavioral and recording procedures, revealed that spatial parameters (spatial information content, coherence, and cluster size) were smaller in the LS than in the hippocampus. Of the 193 LS neurons, 86 were influenced by intracranial self-stimulation rewards; 31 of these 86 were also place-related. These results, together with previous anatomical and behavioral observations, suggest that the spatial information sent from the hippocampus to the LS is modulated by and interacts with signals related to reward in the LS. © 2006 Wiley-Liss, Inc. [source] Inequality and Social Conflict Over Land in AfricaJOURNAL OF AGRARIAN CHANGE, Issue 3 2004PAULINE E. PETERS The paper proposes that reports of pervasive competition and conflict over land in sub-Saharan Africa belie a current image of negotiable and adaptive customary systems of landholding and land use but, instead, reveal processes of exclusion, deepening social divisions and class formation. Cases of ambiguous and indeterminate outcomes among claimants over land do occur, but the instances of intensifying conflict over land, deepening social rifts and expropriation of land beg for closer attention. More emphasis needs to be placed by analysts on who benefits and who loses from instances of ,negotiability' in access to land, an analysis that, in turn, needs to be situated in broader political economic and social changes taking place, particularly during the past thirty or so years. This requires a theoretical move away from privileging contingency, flexibility and negotiability that, willy-nilly, ends by suggesting an open field, to one that is able to identify those situations and processes (including com-modification, structural adjustment, market liberalization and globalization) that limit or end negotiation and flexibility for certain social groups or categories. [source] The biology of Agriotes sordidus Illiger (Col., Elateridae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2004L. Furlan Abstract:, This paper describes the life cycle, including adult behaviour, oviposition, larval and pupal development rate of Agriotes sordidus Illiger. Each larva passed through up to eight to 13 instars. The larval size range of each instar was defined. Larvae need live vegetable tissues to survive and grow, otherwise most die within 40 days. Resistance to starvation increases with the age of the larvae (last instars can survive up to 1 year without food at 20°C). Each instar passes through three phases: mandible hardening and darkening, feeding, pre-moulting. The intense feeding (damaging plants) phase lasted <25% of the whole development time. They are poliphagous and the rate of larval development does not vary with host-plant type (maize, alfalfa). Provided sufficient soil moisture and food are present, larval development rate strongly depends on soil temperature. The duration of each instar increased with the age of the larvae. No larval growth was observed below 9°C. Under laboratory conditions the average heat sum (above a base of 9°C) required for development from egg to adult was about 3900 DD. Similar results were found in the rearing cages and in the open field. At the latitudes of the regions where this study was carried out (northern Italy, Veneto between 45°34,00,,N and 45°42,00,,N and central-south Italy, Molise, between 41°49,720,,N and 41°56,501,,N) the 6th instar (which normally is the first one passing 10 mm in length) is attained by September of the same oviposition year. Pupae can be found between the end of May and September mostly in the upper soil layer. Their transformation into adults took about 16 days at 25°C. Larvae of different stages overwintered by burrowing deep into the soil. Vertical migrations during the year are described: they depend mostly on soil temperatures from October to early spring. The adults overwintered and laid eggs in the subsequent spring. At lower latitudes or in warm seasons most of the population completed its life cycle (from egg to egg) in 24 months over three calendar years. At more northern latitudes, part (sometimes most) of the population completed the whole life cycle in about 36 months over four calendar years. [source] Viral vectors carrying NR1 sequences injected into rat hippocampus interfered with learning and memoryJOURNAL OF NEUROCHEMISTRY, Issue 2002V. Cheli NMDA receptors are relevant to learning and memory as has been shown both by pharmacological and genetic manipulations. Gene knockouts are useful for investigating in vivo functions, but genetic deletions unrestricted in time or region, may lead to developmental defects or death. The challenge is to control expression with temporal and spatial restrictions in the brain. Viral vectors derived from herpes type-1 neurotropic virus are interesting candidates for it. To regulate gene expression of the NMDA receptor NR1 subunit, vectors carrying either sense NR1(+) or antisense NR1(,) sequences and that of the green fluorescent protein (GFP), were constructed. The protein or RNA expression were corroborated in cell culture by GFP autofluorescence, Western blots, immunofluorescence and RT-PCR, and in rat brain, by Western blots and GFP autofluorescence. The vectors were injected into the dorsal hippocampus of adult male Wistar rats. After 6 days each rat was trained and evaluated for both habituation to an open field and inhibitory avoidance to a foot-shock. The rats injected with GFP-NR1(+) vectors showed habituation and learned the inhibitory avoidance, like sham operated rats; while animals injected with GFP-NR1(,) vectors did not. The vectors were useful to modify endogenous gene expression at a defined period, in restricted regions, leading to investigate in vivo functions. NR1 subunit in the hippocampus is involved in mechanisms leading to habituation and to avoidance behaviour, since even a slight change in the availability of NR1 interfered with them. [source] Intracerebroventricular Injections of Prolactin Counteract the Antagonistic Effect of Bromocriptine on Rabbit Maternal BehaviourJOURNAL OF NEUROENDOCRINOLOGY, Issue 12 2004G. González-Mariscal Abstract To investigate the participation of prolactin in nest-building and maternal behaviour in rabbits, we administered (from pregnancy day 26 to parturition) rabbit prolactin (rbPRL; or vehicle) intracerebroventricularly (i.c.v.) to primiparous animals injected with bromocriptine subcutaneously (s.c.). Control females (given vehicle s.c. and i.c.v.) built a maternal nest (of straw and body hair) in 77% of cases. This proportion decreased to 19% in the bromocriptine-only group (P < 0.05) and increased to 93% in the group given bromocriptine plus rbPRL (P > 0.05). Maternal behaviour (i.e. the adoption of a crouching posture over the litter inside the nest box) was expressed by 77% of control rabbits, 19% of bromocriptine-only animals (P < 0.05) and 57% of females given bromocriptine plus rbPRL (P > 0.05). Values of nonmaternal activities (i.e. scent-marking, ambulation in an open field) were similar among the three studied groups. These results suggest that prolactin, acting in late pregnancy, plays a major role in the stimulation of nest-building and maternal behaviour in rabbits. [source] Urocortin III, A Brain Neuropeptide of the Corticotropin-Releasing Hormone Family: Modulation by Stress and Attenuation of Some Anxiety-Like BehavioursJOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2004M. Venihaki Abstract Following its discovery 20 years ago, corticotropin-releasing hormone (CRH) has been postulated to mediate both hormonal and behavioural responses to stressors. Here, we characterize and describe a behavioural role for the murine gene, UcnIII, which encodes a recently discovered CRH-related neuropeptide, urocortin III. We found that mouse UcnIII is expressed predominantly in regions of the brain known to be involved in stress-related behaviours, and its expression in the hypothalamus increases following restraint. In addition, we found that intracerebroventricular administration of mUcnIII stimulates behaviours that are associated with reduced anxiety, including exploration of an open field and decreased latency to enter the lit compartment of a dark-light chamber, but has no effect on the elevated-plus maze. Finally, we found that mUcnIII does not exert any effects on the hormonal stress response. Based upon our findings, UcnIII may be an endogenous brain neuropeptide that is modulated by stress and stimulates behaviours associated with reduced anxiety. In this capacity, UcnIII may attenuate stress-related behaviours, which may be useful both to help cope with stressful situations as well as to avoid pathology associated with excessive reaction to stressors. [source] Apoptotic and behavioral sequelae of mild brain trauma in miceJOURNAL OF NEUROSCIENCE RESEARCH, Issue 4 2007David Tweedie Abstract Mild traumatic brain injury (mTBI) is a not uncommon event in adolescents and young adults. Although it does not result in clear morphological brain defects, it is associated with long-term cognitive, emotional, and behavioral problems. Herein, we characterized the biochemical and behavioral changes associated with experimental mTBI in mice that may act as either targets or surrogate markers for interventional therapy. Specifically, mTBI was induced by 30-g and 50-g weight drop, and at 8 and 72 hr thereafter markers of cellular apoptosis,caspase-3, Bax, apoptosis-inducing factor (AIF), and cytochrome-c (Cyt-c),were quantified by Western blot analysis in hippocampus ipsilateral to the impact. Levels of amyloid-, precursor protein (APP) were also measured, and specific behavioral tests,passive avoidance, open field, and forced swimming (Porsolt) paradigms,were undertaken to assess learning, emotionality, and emotional memory. In the absence of hemorrhage or infarcts, as assessed by triphenyltetrazolium chloride staining, procaspase-3 and Bax levels were markedly altered following mTBI at both times. No cleaved caspase-3 was detected, and levels of AIF and Cyt-c, but not APP, were significantly changed at 72 hr. Mice subjected to mTBI were indistinguishable from controls by neurological examination at 1 and 24 hr, and by passive avoidance/open field at 72 hr, but could be differentiated in the forced swimming paradigm. In general, this model mimics the diffuse effects of mTBI on brain function associated with the human condition and highlights specific apoptotic proteins and a behavioral paradigm as potential markers for prospective interventional strategies. © 2007 Wiley-Liss, Inc. [source] Mice with the deleted neurofilament of low molecular weight (Nefl) gene: 2.JOURNAL OF NEUROSCIENCE RESEARCH, Issue 6 2005Effects on motor functions, spatial orientation Abstract Mice with a null mutation of the Nefl gene were compared with normal controls in tests of motor activity, equilibrium, and spatial orientation. Despite a normal capacity to ambulate, NFL ,/, mice had fewer rears in an open field, crossed fewer segments on stationary beams, and fell more frequently when suspended on a horizontal bar. In addition, the distance swum before reaching the escape platform was greater in NFL ,/, mice than in controls during acquisition of place learning in the Morris water maze at the start of training. The motor impairments were linearly correlated with increased cytochrome oxidase activity seen in cerebellum and brainstem. These results indicate that, as early as 6 months, depletion of the NFL protein is sufficient to cause mild sensorimotor dysfunctions and spatial deficits, but without overt signs of paresis. © 2005 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||