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Anterior Hypothalamus (anterior + hypothalamus)
Selected AbstractsEpigenetic control of translation regulation: Alterations in histone H3 lysine 9 post-translation modifications are correlated with the expression of the translation initiation factor 2B (Eif2b5) during thermal control establishmentDEVELOPMENTAL NEUROBIOLOGY, Issue 2 2010Tatiana Kisliouk Abstract Thermal control set point is regulated by thermosensitive neurons of the preoptic anterior hypothalamus (PO/AH) and completes its development during postnatal critical sensory period. External stimuli, like increase in environmental temperature, influence the neuronal protein repertoire and, ultimately, cell properties via activation or silencing of gene transcription, both of which are regulated by the "histone code."" Here, we demonstrated an increase in global histone H3 lysine 9 (H3K9) acetylation as well as H3K9 dimethylation in chick PO/AH during heat conditioning at the critical period of sensory development. In contrast to the global profile of H3K9 modifications, acetylation and dimethylation patterns of H3K9 at the promoter of the catalytic subunit of eukaryotic translation initiation factor 2B (Eif2b5) were opposite to each other. During heat conditioning, there was an increase in H3K9 acetylation at the Eif2b5 promoter, simultaneously with decrease in H3K9 dimethylation. These alterations coincided with Eif2b5 mRNA induction. Moreover, exposure to excessive heat during the critical period resulted in long-term effect on both H3K9 tagging at the Eif2b5 promoter and Eif2b5 mRNA expression. These data suggest a role for dynamic H3K9 post-translational modifications in global translation regulation during the thermal control establishment. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2010 [source] A role for eukaryotic translation initiation factor 2B (eIF2B) in taste memory consolidation and in thermal control establishment during the critical period for sensory developmentDEVELOPMENTAL NEUROBIOLOGY, Issue 6 2007Sharon Tirosh Abstract All species exhibit critical periods for sensory development, yet very little is known about the molecules involved in the changes in the network wiring that underlies this process. Here the role of transcription regulation of the translation machinery was determined by evaluating the expression of eIF2B,, an essential component of translation initiation, in both taste-preference development and thermal control establishment in chicks. Analysis of the expression pattern of this gene after passive-avoidance training revealed clear induction of eIF2B, in both the mesopallium intermediomediale (IMM) and in the striatum mediale (StM). In addition, a correlation was found between the concentration of methylanthranilate (MeA), which was the malaise substrate in the passive-avoidance training procedure, the duration of memory, and the expression level of eIF2B,. Training chicks on a low concentration of MeA induced short-term memory and low expression level of eIF2B,, whereas a high concentration of MeA induced long-term memory and a high expression level of eIF2B, in both the IMM and StM. Furthermore, eIF2B, -antisense "knock-down" not only reduced the amount of eIF2B, but also attenuated taste memory formation. In order to determine whether induction of eIF2B, is a general feature of neuronal plasticity, we checked whether it was induced in other forms of neuronal plasticity, with particular attention to its role in temperature control establishment, which represents hypothalamic-related plasticity. It was established that eIF2B, -mRNA was induced in the preopotic anterior hypothalamus during heat conditioning. Taken together, these results correlate eIF2B, with sensory development. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007. [source] Estrogen modulates neuronal movements within the developing preoptic area,anterior hypothalamusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2007John Gabriel Knoll Abstract The preoptic area,anterior hypothalamus (POA-AH) is characterized by sexually dimorphic features in a number of vertebrates and is a key region of the forebrain for regulating physiological responses and sexual behaviours. Using live-cell fluorescence video microscopy with organotypic brain slices, the current study examined sex differences in the movement characteristics of neurons expressing yellow fluorescent protein (YFP) driven by the Thy-1 promoter. Cells in slices from embryonic day 14 (E14), but not E13, mice displayed significant sex differences in their basal neuronal movement characteristics. Exposure to 10 nm estradiol-17, (E2), but not 100 nm dihydrotestosterone, significantly altered cell movement characteristics within minutes of exposure, in a location-specific manner. E2 treatment decreased the rate of motion of cells located in the dorsal POA-AH but increased the frequency of movement in cells located more ventrally. These effects were consistent across age and sex. To further determine whether early-developing sex differences in the POA-AH depend upon gonadal steroids, we examined cell positions in mice with a disruption of the steroidogenic factor-1 gene, in which gonads do not form. An early-born cohort of cells were labelled with the mitotic indicator bromodeoxyuridine (BrdU) on E11. More cells were found in the POA-AH of females than males on the day of birth (P0) regardless of gonadal status. These results support the hypothesis that estrogen partially contributes to brain sexual dimorphism through its influence on cell movements during development. Estrogen's influence may be superimposed upon a pre-existing genetic bias. [source] Noxious Somatic Inputs to Hypothalamic-Midbrain Projection Neurones: a Comparison of the Columnar Organisation of Somatic and Visceral Inputs to the Periaqueductal Grey in the RatEXPERIMENTAL PHYSIOLOGY, Issue 2 2002D. M. Parry The induction of Fos protein was used to localise hypothalamic neurones activated by noxious somatic stimulation. This was combined with retrograde transport of fluorescent latex microspheres from identified ,pressor' and ,depressor' sites in the dorsolateral/lateral or ventrolateral columns of the periaqueductal grey (PAG). Fos-positive neurones were found throughout the rostral hypothalamus. Of those neurones activated by noxious somatic stimuli that projected to the PAG all but one was retrogradely labelled from sites that included the lateral column. Only one neurone was double labelled following injection of tracer at a depressor site in the ventrolateral PAG. This is in marked contrast to visceroresponsive hypothalamic neurones, a larger proportion of which project to the PAG and which, as reported previously, preferentially target depressor sites in the ventrolateral sector. These results are discussed in relation to the roles of the anterior hypothalamus and the different functional columns of the PAG in co-ordinating autonomic and sensory functions in response to nociceptive inputs originating in different peripheral domains. [source] C-Nociceptor Activation of Hypothalamic Neurones and the Columnar Organisation of Their Projections to the Periaqueductal Grey in the RatEXPERIMENTAL PHYSIOLOGY, Issue 2 2002B. M. Lumb The induction of Fos protein was used to localise hypothalamic neurones activated by ramps of noxious skin heating delivered at a rate of 2.5 °C s,1 to preferentially activate C-nociceptors. This was combined with retrograde transport of cholera toxin subunit B from identified ,pressor' and ,depressor' sites in the dorsolateral/lateral or the ventrolateral columns of the periaqueductal grey. Fos-positive neurones were found throughout the rostral hypothalamus. Despite this wide distribution, those neurones double labelled retrogradely from the periaqueductal grey were focused in the lateral area of the anterior hypothalamus. More than 20% of Fos-positive neurones in this region projected to depressor sites in the ventrolateral periaqueductal grey, and 10% projected to its dorsolateral/lateral sector. These results are discussed in relation to the peripheral inputs to hypothalamic-midbrain pathways and their role in the cardiovascular responses to different components of the pain signal. [source] Role of the Ventromedial Hypothalamic Orexin-1 Receptors in Regulation of Gastric Acid Secretion in Conscious RatsJOURNAL OF NEUROENDOCRINOLOGY, Issue 3 2009A. Eliassi Orexins play an important role on the central nervous system to modulate gastric acid secretion. The orexin receptors are distributed within the hypothalamus, and expression of orexin-1 receptors (OX1R) is greatest in the anterior hypothalamus and ventromedial nucleus. Therefore, we hypothesised that ventromedial hypothalamic OX1R may be involved in the control of gastric acid secretion. To address this question, we examined the effects of orexin-A and a selective OX1R antagonist, SB-3345867, on gastric acid secretion in pyloric-ligated conscious rats. Intraventromedial injection of orexin-A (0.5,2 ,g/,l) stimulated gastric acid secretion in a dose-dependent manner. This stimulatory effect of orexin-A persisted over 3 h. In some experiments, SB-3345867 (10 mg/kg i.p.) was administered 30 min before orexin-A or saline injections. We found that i.p. injection of SB-334867 suppressed stimulated gastric acid secretion induced by orexin-A (2 ,g/,l). Atropine (5 mg/kg) also inhibited the stimulatory effect of central injection of orexin-A on acid secretion. In conclusion, the present study suggests that endogenous orexin-A acts on the ventromedial hypothalamus to stimulates acid secretion. This stimulatory effect is probably mediated through OX1R. [source] Vasoactive Intestinal Polypeptide Contacts on Gonadotropin-Releasing Hormone Neurones Increase Following Puberty in Female RatsJOURNAL OF NEUROENDOCRINOLOGY, Issue 9 2002L. J. Kriegsfeld Abstract Successful reproduction requires precise temporal coordination among various endocrine and behavioural events. The circadian system regulates daily temporal organization in behaviour and physiology, including neuroendocrine rhythms. The main circadian pacemaker in mammals is located in the suprachiasmatic nuclei (SCN) of the anterior hypothalamus. The SCN sends direct efferents to the reproductive axis via monosynaptic projections to gonadotropin-releasing hormone (GnRH) neurones. This communication generates circadian endocrine rhythms as well as the preovulatory luteinizing hormone (LH) surge necessary for successful ovulation. One SCN peptide thought to be important for the regulation of oestrous cycles is vasoactive intestinal polypeptide (VIP). VIP neurones from the SCN contact GnRH cells, and these cells are preferentially activated during an LH surge in rats. Unlike adult rats, prepubertal females do not exhibit oestrous cycles, nor do they exhibit an LH surge in response to oestradiol positive-feedback. The present study was undertaken to determine the extent to which the development of a ,mature' reproductive axis in female rats is associated with modifications in VIP contacts on GnRH neurones. The brains of diestrus adult (approximately 60 days of age) and prepubertal (21 days of age) female rats were examined using double-label fluorescence immunohistochemistry for VIP and GnRH, with light and confocal microscopy. Although the total number of GnRH-immunoreactive neurones did not differ between adult and prepubertal females, adults had a significant increase in the percentage of GnRH cells receiving VIP contacts compared to juveniles. These data suggest that the development of reproductive hormone rhythms and oestrous cyclicity may be, in part, due to modifications of VIP input to the GnRH system. [source] Distribution of sex steroid hormone receptors in the brain of an African cichlid fish, Astatotilapia burtoniTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 16 2010Lauren A. Munchrath Abstract Sex steroid hormones released from the gonads play an important role in mediating social behavior across all vertebrates. Many effects of these gonadal hormones are mediated by nuclear steroid hormone receptors, which are crucial for integration in the brain of external (e.g., social) signals with internal physiological cues to produce an appropriate behavioral output. The African cichlid fish Astatotilapia burtoni presents an attractive model system for the study of how internal cues and external social signals are integrated in the brain as males display robust plasticity in the form of two distinct, yet reversible, behavioral and physiological phenotypes depending on the social environment. In order to better understand where sex steroid hormones act to regulate social behavior in this species, we have determined the distribution of the androgen receptor, estrogen receptor alpha, estrogen receptor beta, and progesterone receptor mRNA and protein throughout the telencephalon and diencephalon and some mesencephalic structures of A. burtoni. All steroid hormone receptors were found in key brain regions known to modulate social behavior in other vertebrates including the proposed teleost homologs of the mammalian amygdalar complex, hippocampus, striatum, preoptic area, anterior hypothalamus, ventromedial hypothalamus, and ventral tegmental area. Overall, there is high concordance of mRNA and protein labeling. Our results significantly extend our understanding of sex steroid pathways in the cichlid brain and support the important role of nuclear sex steroid hormone receptors in modulating social behaviors in teleosts and across vertebrates. J. Comp. Neurol. 518:3302,3326, 2010. © 2010 Wiley-Liss, Inc. [source] Release of ATP in the central nervous system during systemic inflammation: real-time measurement in the hypothalamus of conscious rabbitsTHE JOURNAL OF PHYSIOLOGY, Issue 1 2007Alexander V. Gourine Receptors for extracellular ATP (both ionotropic and metabotropic) are widely expressed in the CNS both in neurones and glia. ATP can modulate neuronal activity in many parts of the brain and contributes to the central nervous control of several physiological functions. Here we show that during the systemic inflammatory response the extracellular concentrations of ATP increase in the anterior hypothalamus and this has a profound effect on the development of the thermoregulatory febrile response. In conscious rabbits we measured ATP release in real time with novel amperometric biosensors and monitored a marked increase in the concentration of ATP (4.0 ± 0.7 ,m) in the anterior hypothalamus in response to intravenous injection of bacterial endotoxin , lipopolysaccharide (LPS). No ATP release was observed in the posterior hypothalamus. The release of ATP coincided with the development of the initial phase of the febrile response, starting 18 ± 2 min and reaching its peak 45 ± 2 min after LPS injection. Application of the ATP receptor antagonists pyridoxal-5,-phosphate-6-azophenyl-2,,4,-disulphonic acid, Brilliant Blue G or periodate oxidized ATP dialdehyde to the site of ATP release in the anterior hypothalamus markedly augmented and prolonged the febrile response. These data indicate that during the development of the systemic inflammation, ATP is released in the anterior hypothalamus to limit the magnitude and duration of fever. This release may also have a profound effect on the hypothalamic control of other physiological functions in which ATP and related purines have been implicated to play modulatory roles, such as food intake, hormone secretion, cardiovascular activity and sleep. [source] ROLE OF HYPOTHALAMIC ,2 -ADRENOCEPTOR ACTIVITY IN FRUCTOSE-INDUCED HYPERTENSIONCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 10 2006Marcos A Mayer SUMMARY 1The aim of the present study was to investigate the effects of the ,2 -adrenoceptor antagonist yohimbine on blood pressure and heart rate (HR) regulation, as well as on adrenergic and serotoninergic neurotransmission, in fructose hypertensive (F) rats. 2The anterior hypothalamic area of control (C) and F rats was perfused with Ringer's solution containing 10 and 100 µg/mL yohimbine through a microdialysis concentric probe. The effects of yohimbine on mean arterial pressure (MAP) and HR, as well as on hypothalamic dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindole acetic acid (5-HIAA) levels, were measured according to perfusion time. 3Although intrahypothalamic perfusion of yohimbine increased blood pressure in C rats (,MAP 9 ± 1 and 11 ± 2 mmHg for 10 and 100 µg/mL yohimbine, respectively; P < 0.05 vs Ringer's perfusion), the ,-adrenoceptor antagonist did not modify MAP in F. Intrahypothalamic yohimbine had no effect on HR at either concentration tested. Intrahypothalamic perfusion of 10 and 100 µg/mL yohimbine increased DOPAC levels in C rats (135 ± 6 and 130 ± 5% of basal levels, respectively; both n = 6; P < 0.05 vs Ringer's perfusion), but not in F animals (115 ± 6 and 102 ± 6% of basal levels, respectively; both n = 6). In both C and F rats, yohimbine administration induced an increase in 5-HIAA dialysate levels. 4The results of the present study support the notion that ,2 -adrenoceptor tone of the anterior hypothalamus of normotensive rats, which contributes to normal blood pressure regulation, is not involved in the control of HR in either normotensive C or hypertensive F rats. The absence of changes in MAP after yohimbine perfusion in F rats suggests that the ,2 -adrenoceptor tone could be decreased in this group of rats and that this may be responsible for the maintenance of hypertension in this model. Intrahypothalamic perfusion of yohimbine increased DOPAC in the dialysate only in C rats, suggesting changes in presynaptic ,2 -adrenoceptor activity in fructose-overloaded rats. Conversely, increased 5-HIAA levels did not differ between C and F groups. [source] | |||||||||||||||||||||||||