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Systemic Injection (systemic + injection)
Selected AbstractsThe contribution of activated phagocytes and myelin degeneration to axonal retraction/dieback following spinal cord injuryEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2004Lowell T. McPhail Abstract Myelin-derived molecules inhibit axonal regeneration in the CNS. The Long,Evans Shaker rat is a naturally occurring dysmyelinated mutant, which although able to express the components of myelin lacks functional myelin in adulthood. Given that myelin breakdown exposes axons to molecules that are inhibitory to regeneration, we sought to determine whether injured dorsal column axons in a Shaker rat would exhibit a regenerative response absent in normally myelinated Long,Evans (control) rats. Although Shaker rat axons did not regenerate beyond the lesion, they remained at the caudal end of the crush site. Control rat axons, in contrast, retracted and died back from the edge of the crush. The absence of retraction/dieback in Shaker rats was associated with a reduced phagocytic reaction to dorsal column crush around the caudal edge of the lesion. Systemic injection of minocycline, a tetracycline derivative, in control rats reduced both the macrophage response and axonal retraction/dieback following dorsal column injury. In contrast, increasing macrophage activation by spinal injection of the yeast particulate zymosan had no effect on axonal retraction/dieback in Shaker rats. Schwann cell invasion was reduced in minocycline-treated control rats compared with untreated control rats, and was almost undetectable in Shaker rats, suggesting that like axonal retraction/dieback, spinal Schwann cell infiltration is dependent upon macrophage-mediated myelin degeneration. These results indicate that following spinal cord injury the phagocyte-mediated degeneration of myelin and subsequent exposure of inhibitory molecules to the injured axons contributes to their retraction/dieback. [source] Inhibition of aggression by progesterone and its metabolites in female Syrian hamstersAGGRESSIVE BEHAVIOR, Issue 5 2001Jess G. Kohlert Abstract The sequence of estradiol and progesterone is known to inhibit the expression of aggression in female hamsters. Despite the key importance of progesterone in the inhibition of aggression, little is known of the mechanisms through which progesterone may exert this effect. Three experiments were performed to assess the degree to which metabolites of progesterone can affect aggression in female Syrian hamsters. Systemic estradiol treatment followed by injections of either progesterone (300 ,g IP) or 4-pregnen-21-ol-3,20-dione (DOC, 300 ,g IP) reliably inhibited aggression. Systemic injection (75, 150, or 300 ,g IP) of either 5,-pregnan-3,,21-diol-20-one (THDOC) or 5,-pregnan-3,-ol-20-one (3,,5,-THP) did not affect aggression. Intracerebroventricular infusion of 3,,5,-THP following systemic estradiol treatment also did not affect aggression. In a third experiment, female hamsters were given systemic treatments with estradiol and progesterone that were subthreshold with respect to inhibition of aggression. In these females, intracerebroventricular infusion of THDOC inhibited aggression. These results indicate that metabolites of progesterone can inhibit aggression, most notably in synergy with progesterone itself. Aggr. Behav. 27:372,381, 2001. © 2001 Wiley-Liss, Inc. [source] N -methyl-d-aspartate Receptor Responses Are Differentially Modulated by Noncompetitive Receptor Antagonists and Ethanol in Inbred Long-Sleep and Short-Sleep Mice: Behavior and ElectrophysiologyALCOHOLISM, Issue 12 2000Taleen Hanania Background: Short-sleep (SS) mice exhibit higher locomotor activity than do long-sleep (LS) mice when injected with low doses of ethanol or the noncompetitive N -methyl-D-aspartate receptor (NMDAR) antagonist MK-801 (dizocilpine). SS mice also have higher densities of brain NMDARs. However, two strains of LS X SS recombinant inbred (RI) mice also show differential activation to ethanol and MK-801, but have similar numbers of NMDARs. Here we used inbred LS (ILS) and SS (ISS) mice to investigate further the relationship between NMDARs and sensitivity to the stimulant effects of low doses of ethanol. Methods: Open field activity and spontaneous alternations were measured after saline or drug injection. [3H]MK-801 binding parameters were determined in hippocampus, cortex, striatum, and nucleus accumbens. Extracellular field excitatory postsynaptic potentials (fEPSPs) were recorded in the CA1 region of hippocampal slices. Results: Systemic injection of either ethanol or MK-801 increased locomotor activity to a greater extent in ISS mice than in ILS mice. The competitive NMDAR antagonist 2-carboxypiperazin-4-yl-propyl-1,1phosphonic acid (±CPP) depressed activity of ILS, but not ISS, mice. No strain differences were observed in spontaneous alternations or in the number or affinity of NMDARs in the brain regions examined. Likewise, the magnitudes of hippocampal NMDAR-mediated fEPSPs were similar in ILS and ISS mice and were inhibited to the same extent by a competitive NMDAR antagonist. However, both ethanol and the NMDAR NR2B receptor antagonist ifenprodil inhibited the late component of hippocampal NMDAR fEPSPs to a greater extent in ISS, than in ILS, mice. Conclusions: Differential ethanol- and MK-801-induced behavioral activation in ILS and ISS mice was not associated with differences in NMDAR number. Nonetheless, pharmacological differences in hippocampal NMDAR responsiveness suggest that ISS mice express NMDARs that have a greater sensitivity to noncompetitive, but not competitive, NMDAR antagonists. These differences, which may reflect differences in NMDAR subunit composition, could underlie the differential responsiveness to low doses of ethanol in ILS and ISS mice. [source] Sustained neocortical neurogenesis after neonatal hypoxic/ischemic injuryANNALS OF NEUROLOGY, Issue 3 2007Zhengang Yang PhD Objective Neocortical neurons are sensitive to hypoxic-ischemic (H-I) injuries at term and their demise contributes to neurological disorders. Here we tested the hypothesis that the subventricular zone of the immature brain regenerates neocortical neurons, and that this response is sustained. Methods Systemic injections of 5-bromo-2,-deoxyuridine (BrdU) and intraventricular injections of replication-deficient retroviruses were used to label newly born cells, and confocal microscopy after immunofluorescence was used to phenotype the new cells from several days to several months after perinatal H-I in the postnatal day 6 rat. Quantitative polymerase chain reaction was used to evaluate chemoattractants, growth factors, and receptors. Results Robust production of new neocortical neurons after perinatal H-I occurs. These new neurons are descendants of the subventricular zone, and they colonize the cell-sparse columns produced by the injury to the neocortex. These columns are populated by reactive astrocytes and microglia. Surprisingly, this neuronogenesis is sustained for months. Molecular analyses demonstrated increased neocortical production of insulin-like growth factor-1 and monocyte chemoattractant factor-1 (but statistically insignificant production of erythropoietin, brain-derived neurotrophic factor, glial-derived neurotrophic factor, and transforming growth factor-,). Interpretation The young nervous system has long been known to possess a greater capacity to recover from injury than the adult system. Our data indicate that H-I injury in the neonatal brain initiates an enduring regenerative response from the subventricular zone. These data suggest that additional mechanisms than those previously surmised contribute to the remarkable ability of the immature brain to recover from injury. Ann Neurol 2007 [source] Seizure Suppression by Adenosine A1 Receptor Activation in a Mouse Model of Pharmacoresistant EpilepsyEPILEPSIA, Issue 7 2003Nicolette Gouder Summary: Purpose: Because of the high incidence of pharmacoresistance in the treatment of epilepsy (20,30%), alternative treatment strategies are needed. Recently a proof-of-principle for a new therapeutic approach was established by the intraventricular delivery of adenosine released from implants of engineered cells. Adenosine-releasing implants were found to be effective in seizure suppression in a rat model of temporal lobe epilepsy. In the present study, activation of the adenosine system was applied as a possible treatment for pharmacoresistant epilepsy. Methods: A mouse model for drug-resistant mesial temporal lobe epilepsy was used, in which recurrent spontaneous seizure activity was induced by a single intrahippocampal injection of kainic acid (KA; 200 ng in 50 nl). Results: After injection of the selective adenosine A1 -receptor agonist, 2-chloro- N6 -cyclopentyladenosine (CCPA; either 1.5 or 3 mg/kg, i.p.), epileptic discharges determined in EEG recordings were completely suppressed for a period of ,3.5 h after the injections. Seizure suppression was maintained when 8-sulfophenyltheophylline (8-SPT), a non,brain-permeable adenosine-receptor antagonist, was coinjected systemically with CCPA. In contrast, systemic injection of carbamazepine or vehicle alone did not alter the seizure pattern. Conclusions: This study demonstrates that activation of central adenosine A1 receptors leads to the suppression of seizure activity in a mouse model of drug-resistant epilepsy. We conclude that the local delivery of adenosine into the brain is likely to be effective in the control of intractable seizures. [source] Activation of group II mGlu receptors blocks the enhanced drug taking induced by previous exposure to amphetamineEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2005Jeong-Hoon Kim Abstract Repeated exposure to amphetamine (AMPH) leads to the development of behavioural sensitization that can be demonstrated in rats as enhanced locomotor responding to and self-administration of the drug. Glutamate systems are known to participate in the induction and expression of sensitization by psychostimulants. Group II metabotropic glutamate receptors (mGluRs), because they negatively regulate both vesicular and nonvesicular glutamate release, are thus well positioned to gate its expression. Here we report that the expression of locomotor sensitization by AMPH is completely prevented by a systemic injection of the selective group II mGluR agonist LY379268 at a dose that produced no effects when administered alone. The activation of group II mGluRs in AMPH-sensitized rats also reduced the enhanced overflow of both dopamine and glutamate normally observed in the nucleus accumbens, a brain region critical for the generation of locomotor and drug self-administration behaviours. To directly determine the effect of group II mGluR activation on enhanced drug self-administration, AMPH-sensitized rats were allowed to self-administer a mixture of LY379268 and AMPH. These rats continued to self-administer but did not exhibit the enhanced work output and drug intake observed in AMPH-sensitized rats self-administering AMPH alone. Thus, activating group II mGluRs prevents the expression of different manifestations of AMPH sensitization including enhanced self-administration of the drug. These receptors may represent a potentially important target for therapeutic intervention directed at drugs of abuse. [source] A single application of MK801 causes symptoms of acute psychosis, deficits in spatial memory, and impairment of synaptic plasticity in ratsHIPPOCAMPUS, Issue 2 2008Denise Manahan-Vaughan Abstract Schizophrenia is mostly a progressive psychiatric illness. Although cognitive changes in chronic schizophrenia have been investigated, little is known about the consequences of a single psychotic episode on memory mechanisms and formation. We investigated changes in hippocampal long-term potentiation (LTP) and spatial memory in a rat model of an acute psychotic episode. Application of NMDA receptor antagonists, such as MK801 (dizolcilpine) in rats, have been shown to give rise to an acute and short-lasting behavioral state, which mirrors many symptoms of schizophrenia. Furthermore, NMDA antagonist-intake in humans elicits symptoms of schizophrenia such as hallucinations, delusions, and affective blunting. We therefore treated animals with a single systemic injection of MK801 (5 mg/kg). Increased stereotypy, locomotion, and ataxia were evident immediately after MK801-treatment, with effects disappearing within 24 h. MK801-treatment caused a disruption of prepulse inhibition of the acoustic startle reflex, 1 day but not 7 or 28 days after treatment. These effects were consistent with the occurrence of an acute psychotic episode. LTP was profoundly impaired in freely moving rats 7 days after MK801 application. Four weeks after treatment, a slight recovery of LTP was seen, however marked deficits in long-term spatial memory were evident. These data suggest that treatment with MK801 to generate an acute psychotic episode in rats, gives rise to grave disturbances in synaptic plasticity and is associated with lasting impairments with the ability to form spatial memory. © 2007 Wiley-Liss, Inc. [source] Circulating cell wall components derived from gram-negative, not gram-positive, bacteria cause a profound induction of the gene-encoding Toll-like receptor 2 in the CNSJOURNAL OF NEUROCHEMISTRY, Issue 3 2001Nathalie Laflamme The recent characterization of human homologs of Toll may be the missing link for the transduction events leading to nuclear factor-,B (NF-,B) activity and proinflammatory gene transcription during innate immune response. Mammalian cells may express as many as 10 distinct Toll-like receptors (TLRs), although TLR2 is a key receptor for recognizing cell wall components of Gram-positive bacteria. The present study investigated the effects of circulating bacterial cell wall components on the expression of the gene-encoding TLR2 across the mouse brain. Surprisingly, while Gram-negative components caused a robust increase in TLR2 transcription within the cerebral tissue, peptidoglycan (PGN) and lipoteichoic acid (LTA), either alone or combined, failed to modulate the receptor transcript. Indeed, the mRNA levels for TLR2 in the choroid plexus and few other regions of the brain remained similar between vehicle-, LTA-, PGN-, and LTA/PGN-administered mice at all the times evaluated (i.e. 30 min to 24 h post-intraperitoneal injection). This contrasts with the profound de novo expression of TLR2 following a single systemic injection of the lipopolysaccharide (LPS). The signal was first detected in regions devoid of blood,brain barrier and few blood vessels and microcapillaries. A second wave of TLR2 expression was also detected from these structures to their surrounding parenchymal cells that stained for a microglial marker iba1. The rapid induction of I,B, (index of NF-,B activity) and up-regulation of the adaptor protein MyD88 suggest that LPS-induced TLR2 transcription may be dependent on the NF-,B pathway. These data provide the evidence that TLR2 is not only present in the brain, but its encoding gene is regulated by cell wall components derived from Gram-negative, not Gram-positive, bacteria. The robust wave of TLR2-expressing microglial cells may have a determinant impact on the innate immune response that occurs in the brain during systemic infection by Gram-negative, not Gram-positive, bacteria. [source] Cocaine- and Amphetamine-Regulated Transcript is Present in Hypothalamic Neuroendocrine Neurones and is Released to the Hypothalamic-Pituitary Portal CircuitJOURNAL OF NEUROENDOCRINOLOGY, Issue 3 2003P. J. Larsen Abstract Cocaine- and amphetamine-regulated transcript (CART) is present in a number of hypothalamic nuclei. Besides actions in circuits regulating feeding behaviour and stress responses, the hypothalamic functions of CART are largely unknown. We report that CART immunoreactivity is present in hypothalamic neuroendocrine neurones. Adult male rats received a systemic injection of the neuronal tracer Fluorogold (FG) 2 days before fixation, and subsequent double- and triple-labelling immunoflourescence analysis demonstrated that neuroendocrine CART-containing neurones were present in the anteroventral periventricular, supraoptic, paraventricular (PVN) and periventricular nuclei of the hypothalamus. In the PVN, CART-positive neuroendocrine neurones were found in all of cytoarchitectonically identified nuclei. In the periventricular nucleus, approximately one-third of somatostatin cells were also CART-immunoreactive. In the medial parvicellular subnucleus of the PVN, CART and FG coexisted with thyrotrophin-releasing hormone, whereas very few of the corticotrophin-releasing hormone containing cells were CART-immunoreactive. In the arcuate nucleus, CART was extensively colocalized with pro-opiomelanocortin in the ventrolateral part, but completely absent from neuroendocrine neurones of the dorsomedial part. To assess the possible role of CART as a hypothalamic-releasing factor, immunoreactive CART was measured in blood samples from the long portal vessels connecting the median eminence with the anterior pituitary gland. Adult male rats were anaesthetized and the infundibular stalk exposed via a transpharyngeal approach. The long portal vessels were transected and blood collected in 30-min periods (one prestimulatory and three poststimulatory periods). Compared to systemic venous plasma samples, baseline concentrations of immunoreactive CART were elevated in portal plasma. Exposure to sodium nitroprusside hypotension triggered a two-fold elevation of portal CART42-89 immunoreactivity throughout the 90-min stimulation period. In contrast, the concentration of portal plasma CART immunoreactivity dropped in the vehicle infused rats. The current study provides further evidence that CART is a neuroendocrine-releasing factor with a possible impact on anterior pituitary function during states of haemodynamic stress. [source] Ghrelin Receptor Antagonism Decreases Alcohol Consumption and Activation of Perioculomotor Urocortin-Containing NeuronsALCOHOLISM, Issue 9 2010Simranjit Kaur Background:, The current therapies for alcohol abuse disorders are not effective in all patients, and continued development of pharmacotherapies is needed. One approach that has generated recent interest is the antagonism of ghrelin receptors. Ghrelin is a gut-derived peptide important in energy homeostasis and regulation of hunger. Recent studies have implicated ghrelin in alcoholism, showing altered plasma ghrelin levels in alcoholic patients as well as reduced intakes of alcohol in ghrelin receptor knockout mice and in mice treated with ghrelin receptor antagonists. The aim of this study was to determine the neuroanatomical locus/loci of the effect of ghrelin receptor antagonism on alcohol consumption using the ghrelin receptor antagonist, D-Lys3-GHRP-6. Methods:, In Experiment 1, male C57BL/6J mice were injected with saline 3 hours into the dark cycle and allowed access to 15% (v/v) ethanol or water for 2 hours in a 2-bottle choice experiment. On test day, the mice were injected with either saline or 400 nmol of the ghrelin receptor antagonist, D-Lys3-GHRP-6, and allowed to drink 15% ethanol or water for 4 hours. The preference for alcohol and alcohol intake were determined. In Experiment 2, the same procedure was followed as in Experiment 1 but mice were only allowed access to a single bottle of 20% ethanol (v/v), and alcohol intake was determined. Blood ethanol levels were analyzed, and immunohistochemistry for c-Fos was carried out to investigate changes in neural activity. To further elucidate the mechanism by which D-Lys3-GHRP-6 affects alcohol intake, in Experiment 3, the effect of D-Lys3-GHRP-6 on the neural activation induced by intraperitoneal ethanol was investigated. For the c-Fos studies, brain regions containing ghrelin receptors were analyzed, i.e. the perioculomotor urocortin population of neurons (pIIIu), the ventral tegmental area (VTA), and the arcuate nucleus (Arc). In Experiment 4, to test if blood ethanol concentrations were affected by D-Lys3-GHRP-6, blood samples were taken at 2 time-points after D-Lys3-GHRP-6 pretreatment and systemic ethanol administration. Results:, In Experiment 1, D-Lys3-GHRP-6 reduced preference to alcohol and in a follow-up experiment (Experiment 2) also dramatically reduced alcohol intake when compared to saline-treated mice. The resulting blood ethanol concentrations were lower in mice treated with the ghrelin receptor antagonist. Immunohistochemistry for c-Fos showed fewer immunopositive cells in the pIIIu of the antagonist-treated mice but no difference was seen in the VTA or Arc. In Experiment 3, D-Lys3-GHRP-6 reduced the induction of c-Fos by intraperitoneal ethanol in the pIIIu but had no effect in the VTA. In the Arc, there was a significant increase in the number of c-Fos immunopositive cells after D-Lys3-GHRP-6 administration, but the antagonist had no effect on ethanol-induced expression of c-Fos. D-Lys3-GHRP-6-pretreatment also did not affect the blood ethanol concentrations observed after a systemic injection of ethanol when compared to saline-pretreated mice (Experiment 4). Conclusions:, These findings indicate that the action of ghrelin on the regulation of alcohol consumption may occur via the pIIIu. [source] Glycine Receptors in the Nucleus Accumbens Involved in the Ethanol Intake-Reducing Effect of AcamprosateALCOHOLISM, Issue 1 2010PeiPei Chau Background:, We have previously demonstrated that strychnine-sensitive glycine receptors (GlyRs) in the nucleus accumbens (nAc) and nicotinic acetylcholine receptors (nAChRs) in the ventral tegmental area are involved in mediating ethanol (EtOH)-induced elevation of dopamine in the rat mesolimbic dopamine system. This neuronal circuitry was also demonstrated to mediate dopamine elevation in the nAc after both taurine, an endogenous agonist of GlyRs, and acamprosate, a synthetic derivate of homotaurine. The aim of this study was to investigate whether the EtOH intake-reducing effect of acamprosate involves accumbal GlyRs. Methods:, For this purpose, we used a voluntary EtOH consumption model where EtOH medium- and high-preferring rats were implanted with guide cannulae in the nAc. The animals received daily injections of acamprosate or 0.9% NaCl before accessing a bottle of 6% EtOH and a bottle of water. After 2 days, a microinjection of strychnine or vehicle preceded the daily systemic injection and bottle-access period. Results:, Acamprosate, but not saline, decreased EtOH intake. Pretreatment with Ringer in the nAc did not influence EtOH intake in saline or acamprosate-treated animals. Pretreatment with strychnine had no effect on EtOH intake in saline-treated animals, whereas it completely reversed the EtOH intake-reducing effect of acamprosate. Conclusions:, Based on current and previous results, we suggest that acamprosate primarily interacts with accumbal GlyRs and secondarily with ventral tegmental nAChRs, in a similar manner to that previously observed with EtOH and taurine. The interaction between acamprosate and GlyRs does not only influence dopamine output in the nAc but also EtOH consumption, giving further support for our hypothesis that GlyRs are of importance in EtOH reinforcement. [source] GDNF is an Endogenous Negative Regulator of Ethanol-Mediated Reward and of Ethanol Consumption After a Period of AbstinenceALCOHOLISM, Issue 6 2009Sebastien Carnicella Background:, We previously found that activation of the glial cell line-derived neurotrophic factor (GDNF) pathway in the ventral tegmental area (VTA) reduces ethanol-drinking behaviors. In this study, we set out to assess the contribution of endogenous GDNF or its receptor GFR,1 to the regulation of ethanol-related behaviors. Methods:, GDNF and GFR,1 heterozygote mice (HET) and their wild-type littermate controls (WT) were used for the studies. Ethanol-induced hyperlocomotion, sensitization, and conditioned place preference (CPP), as well as ethanol consumption before and after a period of abstinence were evaluated. Blood ethanol concentration (BEC) was also measured. Results:, We observed no differences between the GDNF HET and WT mice in the level of locomotor activity or in sensitization to ethanol-induced hyperlocomotion after systemic injection of a nonhypnotic dose of ethanol and in BEC. However, GDNF and GFR,1 mice exhibited increased place preference to ethanol as compared with their WT littermates. The levels of voluntary ethanol or quinine consumption were similar in the GDNF HET and WT mice, however, a small but significant increase in saccharin intake was observed in the GDNF HET mice. No changes were detected in voluntary ethanol, saccharin or quinine consumption of GFR,1 HET mice as compared with their WT littermates. Interestingly, however, both the GDNF and GFR,1 HET mice consumed much larger quantities of ethanol after a period of abstinence from ethanol as compared with their WT littermates. Furthermore, the increase in ethanol consumption after abstinence was found to be specific for ethanol as similar levels of saccharin intake were measured in the GDNF and GFR,1 HET and WT mice after abstinence. Conclusions:, Our results suggest that endogenous GDNF negatively regulates the rewarding effect of ethanol and ethanol-drinking behaviors after a period of abstinence. [source] Targeting murine small bowel and colon through selective superior mesenteric artery injectionMICROSURGERY, Issue 6 2010Stacy L. Porvasnik M.S. Administration of molecular, pharmacologic, or cellular constructs to the intestinal epithelium is limited by luminal surface mucosal barriers and ineffective intestinal delivery via systemic injection. Many murine models of intestinal disease are used in laboratory investigation today and would benefit specific modulation of the intestinal epithelium. Our aim was to determine the feasibility of a modified microsurgical approach to inject the superior mesenteric artery (SMA) and access the intestinal epithelium. We report the detailed techniques for selective injection of the SMA in a mouse. Mice were injected with methylene blue dye to grossly assess vascular distribution, fluorescent microspheres to assess biodistribution and viral vector to determine biological applicability. The procedure yielded good recovery with minimal morbidity. Tissue analysis revealed good uptake in the small intestine and colon. Biodistribution analysis demonstrated some escape from the intestine with accumulation mainly in the liver. This microsurgical procedure provides an effective and efficient method for delivery of agents to the small intestine and colon, including biological agents. © 2010 Wiley-Liss, Inc. Microsurgery 30:487,493, 2010. [source] The Lung Is The Major Site That Produces Nitric Oxide To Induce Acute Pulmonary Oedema In Endotoxin ShockCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2001Ru Ping Lee SUMMARY 1. The present study was undertaken to determine the locus of nitric oxide (NO) production that is toxic to the lung and produces acute pulmonary oedema in endotoxin shock, to examine and compare the effects of changes in lung perfusate on endotoxin-induced pulmonary oedema (EPE) and to evaluate the involvement of constitutive and inducible NO synthase (cNOS and iNOS, respectively). 2. Experiments were designed to induce septic shock in anaesthetized rats with the administration of Escherichia coli lipopolysaccharide (LPS). Exhaled NO, lung weight (LW)/bodyweight (BW) ratio, LW gain (LWG) and lung histology were measured and observed to determine the degree of EPE 4 h following LPS. The EPE was compared between groups in which LPS had been injected either into the systemic circulation or into the isolated perfused lung. The lung perfusate was altered from whole blood to physiological saline solution (PSS) with 6% albumin to test whether different lung perfusions affected EPE. Pretreatment with various NOS inhibitors was undertaken 10 min before LPS to investigate the contribution of cNOS and iNOS to the observed effects. 3. Endotoxin caused profound systemic hypotension, but little change in pulmonary arterial pressure. The extent of EPE was not different between that induced by systemic injection and that following administration to isolated lungs preparations. Replacement of whole blood with PSS greatly attenuated (P < 0.05) EPE. In blood-perfused lungs, pretreatment with NOS inhibitors, such as N, -nitro- L -arginine methyl ester, aminoguanidine and dexamethasone, significantly prevented EPE (P < 0.05). 4. The major site of NO production through the whole blood is in the lung. The NO production mediated by the iNOS system is toxic to the endothelium in the pulmonary microvasculature. Inhalation of NO for patients with sepsis may be used with clinical caution. Therapeutic consideration of lung extracorporeal perfusion with PSS and pharmacological pretreatment with iNOS inhibitors may be warranted. [source] Effects of central and systemic injections of peripheral benzodiazepine receptor ligands on the anxiolytic actions of ethanol in ratsADDICTION BIOLOGY, Issue 2 2001G. S. Morato The influence of peripheral benzodiazepine receptor ligands Ro5-4864 (0.05 or 1.0 mg/kg, i.p.) or PK11195 (0.05 or 1.0 mg/kg, i.p.) on the anxiolytic effect of ethanol (1.2 g/kg; 14% p/v; i.p.) was investigated in rats tested on the elevated plus-maze. Other animals were injected through intrahippocampal administrations of the ligands (0.5 or 1.0 nmol/0.5 ,l) before ethanol (1.2g/kg; 14% p/v; i.p.) and submitted to the elevated plus-maze test. The results showed that the systemic administration of either ligands 24 hours before the ethanol treatment resulted in a reduced anxiolytic effect of this drug. Only PK11195 reversed the effect of ethanol after intrahippocampal injection. These data suggest that peripheral benzodiazepine receptors play a role in ethanol anxiolysis. [source] Hippocampal mossy fiber sprouting and elevated trkB receptor expression following systemic administration of low dose domoic acid during neonatal developmentHIPPOCAMPUS, Issue 11 2007Paul B. Bernard Abstract We have previously reported that serial systemic injections of low-dose (subconvulsive) domoic acid (DOM) during early postnatal development produces changes in both behavior and hippocampal cytoarchitecture in aged rats (17 months) that are similar to those seen in existing animal models of temporal lobe epilepsy. Herein we report further hippocampal changes, consisting of mossy fiber sprouting and associated changes in the trkB receptor population in young adult (3 months) rats, and further, report that these changes show regional variation throughout the septo-temporal axis of the hippocampus. Groups of Sprague Dawley rat pups were injected daily from postnatal day 8,14 with either saline (n = 23) or 20 ,g/kg DOM (n = 25), tested for key indicators of neonatal neurobehavioral development, and then left undisturbed until ,90 days of age, at which time brain tissue was removed, hippocampi were dissected, fixed and processed using either Timm's stain to visualize hippocampal mossy fiber sprouting (MFS) or trkB immunohistochemistry to visualize full length trkB receptors. Multiple sections from dorsal, mid, and ventral hippocampus were analyzed separately and all measures were conducted using image analysis software. The results indicate significant increases in MFS in the inner molecular layer in treated animals with corresponding changes in trkB receptor density. Further we identified significant increases in trkB receptor density in the hilus of the dentate gyrus and area CA3 and report increased mossy fiber terminal density in the stratum lucidum in treated rats. The magnitude of these changes differed between sections from dorsal, mid, and ventral hippocampus. We conclude that low dose neonatal DOM produces cytoarchitectural changes indicative of abnormal development and/or synaptic plasticity that are progressive with age and show regional variation within the hippocampal formation. © 2007 Wiley-Liss, Inc. [source] Enhanced Chondrogenesis and Wnt Signaling in PTH-Treated Fractures,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 12 2007Sanjeev Kakar Abstract Studies have shown that systemic PTH treatment enhanced the rate of bone repair in rodent models. However, the mechanisms through which PTH affects bone repair have not been elucidated. In these studies we show that PTH primarily enhanced the earliest stages of endochondral bone repair by increasing chondrocyte recruitment and rate of differentiation. In coordination with these cellular events, we observed an increased level of canonical Wnt-signaling in PTH-treated bones at multiple time-points across the time-course of fracture repair, supporting the conclusion that PTH responses are at least in part mediated through Wnt signaling. Introduction: Since FDA approval of PTH [PTH(1,34); Forteo] as a treatment for osteoporosis, there has been interest in its use in other musculoskeletal conditions. Fracture repair is one area in which PTH may have a significant clinical impact. Multiple animal studies have shown that systemic PTH treatment of healing fractures increased both callus volume and return of mechanical competence in models of fracture healing. Whereas the potential for PTH has been established, the mechanism(s) by which PTH produces these effects remain elusive. Materials and Methods: Closed femoral fractures were generated in 8-wk-old male C57Bl/6 mice followed by daily systemic injections of either saline (control) or 30 ,g/kg PTH(1,34) for 14 days after fracture. Bones were harvested at days 2, 3, 5, 7, 10, 14, 21, and 28 after fracture and analyzed at the tissue level by radiography and histomorphometry and at the molecular and biochemical levels level by RNase protection assay (RPA), real-time PCR, and Western blot analysis. Results: Quantitative ,CT analysis showed that PTH treatment induced a larger callus cross-sectional area, length, and total volume compared with controls. Molecular analysis of the expression of extracellular matrix genes associated with chondrogenesis and osteogenesis showed that PTH treated fractures displayed a 3-fold greater increase in chondrogenesis relative to osteogenesis over the course of the repair process. In addition, chondrocyte hypertrophy occurred earlier in the PTH-treated callus tissues. Analysis of the expression of potential mediators of PTH actions showed that PTH treatment significantly induced the expression of Wnts 4, 5a, 5b, and 10b and increased levels of unphosphorylated, nuclear localized ,-catenin protein, a central feature of canonical Wnt signaling. Conclusions: These results showed that the PTH-mediated enhancement of fracture repair is primarily associated with an amplification of chondrocyte recruitment and maturation in the early fracture callus. Associated with these cellular effects, we observed an increase in canonical Wnt signaling supporting the conclusion that PTH effects on bone repair are mediated at least in part through the activation of Wnt-signaling pathways. [source] | |||||||||||||