C-fos In Paraventricular Nucleus Research Articles

Analysis of hippocampal synaptic function in a rodent model of early life stress

Background Early life stress (ELS) is an important risk factor in the aetiology of depression. Developmental glucocorticoid exposure impacts multiple brain regions with the hippocampus being particularly vulnerable. Hippocampal mediated behaviours are dependent upon the ability of neurones to undergo long-term potentiation (LTP), an N-methyl-D-aspartate receptor (NMDAR) mediated process. In this study we investigated the effect of ELS upon hippocampal NMDAR function. Methods Hooded Long-Evans rat pups (n=82) were either undisturbed or maternally separated for 180 minutes per day (MS180) between post-natal day (PND) 1 and PND14. Model validation consisted of sucrose preference (n=18) and novelty supressed feeding (NSFT, n=34) tests alongside assessment of corticosterone (CORT) and paraventricular nucleus (PVN) cFos reactivity to stress and hippocampal neurogenesis (all n=18). AMPA/NMDA ratios (n=19), miniEPSC currents (n=19) and LTP (n=15) were assessed in whole-cell patch clamp experiments in CA1 pyramidal neurones. Results MS180 animals showed increased feeding latency in the NSFT alongside increased overall CORT in the restraint stress experiment and increased PVN cFos expression in males but no changes in neurogenesis or sucrose preference. MS180 was associated with a lower AMPA/NMDA ratio with no change in miniEPSC amplitude or area. There was no difference in short- or long-term potentiation between MS180 and control animals nor were there any changes during the induction protocol. Conclusions The MS180 model showed a behavioural phenotype consistent with previous work. MS180 animals showed increased NMDAR function with preliminary evidence suggesting that this was not concurrent with an increase in LTP.

Chronic variable stress alters hypothalamic-pituitary-adrenal axis function in the female mouse

Chronic stress is often associated with a dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which can greatly increase risk for a number of stress-related diseases, including neuropsychiatric disorders. Despite a striking sex-bias in the prevalence of many of these disorders, few preclinical studies have examined female subjects. Hence, the present study aimed to explore the effects of chronic stress on the basal and acute stress-induced activity of the HPA axis in the female C57BL/6 mouse. We used a chronic variable stress (CVS) paradigm in these studies, which successfully induces physiological and behavioral changes that are similar to those reported for some patients with mood disorders. Using this model, we found pronounced, time-dependent effects of chronic stress on the HPA axis. CVS-treated females exhibited adrenal hypertrophy, yet their pattern of glucocorticoid secretion in the morning resembled that of controls. CVS-treated and control females had similar morning basal corticosterone (CORT) levels, which were both significantly elevated following a restraint stressor. Although morning basal gene expression of the key HPA-controlling neuropeptides corticotropin releasing hormone (CRH), arginine vasopressin (AVP) and oxytocin (OT) was unaltered within the paraventricular nucleus (PVN) by CVS, CVS altered the PVN OT and AVP mRNA responses to acute restraint. In control females, acute stress decreased AVP, but not OT mRNA; whereas, in CVS females, it decreased OT, but not, AVP mRNA. Unlike the morning pattern of HPA activity, in the evening, CVS-treated females showed increased basal CORT with hypoactive responses of CORT and PVN c-Fos immunoreactivity to restraint stress. Furthermore, CVS elevated evening PVN CRH and OT mRNAs in the PVN, but it did not influence anxiety- or depressive-like behavior after a light/dark box or tail suspension test. Taken together, these findings indicate that CVS is an effective model for HPA axis dysregulation in the female mouse and may be relevant for stress-related diseases.

Central nervous regulatory mechanism of myocardial ischemia-reperfusion injury in rats: excitability of neurons in hypothalamic paraventricular nucleus

Objective To evaluate the relationship between excitability of neurons in hypothalamic paraventricular nucleus(PVN) and central nervous regulatory mechanism of myocardial ischemia-reperfusion(I/R) injury in rats. Methods Clean-grade healthy adult male Sprague-Dawley rats, in which PVN catheters were successfully implanted, aged 6-8 weeks, weighing 260-300 g, were divided into 4 groups(n=6 each) using a random number table method: sham operation group(S group), myocardial I/R group(I/R group), γ-aminobutyric acid group(GABA group) and L-glutamic acid group(L-Glu group). Myocardial ischemia was induced by occlusion of the left anterior descending coronary artery for 30 min followed by 120-min reperfusion. Normal saline 2.4 μl/h was infused for 50 min via the PVN catheter starting from 10 min before ischemia in S and I/R groups. GABA 30 μmol/L and L-glutamic acid 30 μmol/L were infused for 50 min via the PVN catheter at a rate of 2.4 μl/h starting from 10 min before ischemia in GABA and L-Glu groups. The heart rate(HR) and mean arterial pressure(MAP) were recorded at 10 min before ischemia(T0), beginning of ischemia(T1), 30 min of ischemia(T2) and 120 min of reperfusion(T3). Rate-pressure product(RPP) was calculated. Blood samples were collected at T3 for determination of plasma cardiac troponin I(cTnI) concentrations by chemiluminescence assay. Rats were then sacrificed and myocardial specimens were obtained for measurement of myocardial infarct size(IS) and area at risk(AAS), and IS/AAR percentage was calculated. PVN tissues were taken to detect the expression of c-fos by Western blot. Results No myocardial infarction was found in group S, and myocardial infarction was marked in the other three groups. Compared with group S, the plasma cTnI concentrations were significantly increased, and the expression of c-fos in PVN was up-regulated in I/R, GABA and L-Glu groups(P<0.05), and MAP, HR and RPP were significantly decreased at T1-3 in I/R and GABA groups and at T3 in group L-Glu(P<0.05). Compared with group I/R, IS and IS/AAR percentage were significantly decreased, the plasma cTnI concentrations were decreased, the expression of c-fos in PVN was down-regulated, and HR, MAP and RPP were decreased at T1, 2 in group GABA, and IS and IS/AAR percentage were significantly increased, the plasma cTnI concentrations were increased, the expression of c-fos in PVN was up-regulated, and HR, MAP and RPP were increased at T1, 2 in group L-Glu(P<0.05). Conclusion Excitability of neurons in hypothalamic PVN is involved in central nervous regulatory mechanism of myocardial I/R injury in rats: decreased excitability can attenuate myocardial I/R injury and increased excitability aggravates myocardial I/R injury. Key words: Paraventricular hypothalamic nucleus; Neurons; Myocardial reperfusion injury

Voluntary physical exercise protects against behavioral and endocrine reactivity to social and environmental stressors in the prairie vole

ABSTRACTPhysical activity can combat detrimental effects of stress. The current study examined the potential protective effects of exercise against a combination of social isolation and chronic mild stress (CMS) in a prairie vole model. Female voles were isolated for 4 weeks, with the addition of CMS during the final 2 weeks. Half of the voles were allowed access to a running wheel during this final 2 weeks, while the other half remained sedentary. Animals underwent behavioral tests to assess depressive- and anxiety-behaviors. In a subset of animals, plasma was collected 10 minutes after behavioral testing for corticosterone analysis. In a separate subset, brains were collected 2 hours after behavioral testing for cFos analysis in the paraventricular nucleus (PVN). Voles in the exercise group displayed significantly lower depressive- and anxiety-behaviors, and displayed significantly lower corticosterone levels, compared to animals in the sedentary group. There was no difference in PVN cFos activity between groups. Interestingly, animals that moderately exercised displayed lower levels of depressive-behavior and attenuated corticosterone reactivity compared to animals in the low and high activity subgroups. These findings suggest that physical activity can protect against a combination of social and environmental stressors.

36th International Symposium on Intensive Care and Emergency Medicine : Brussels, Belgium. 15-18 March 2016.

36th International Symposium on Intensive Care and Emergency Medicine : Brussels, Belgium. 15-18 March 2016.

Inhibitory Effects of Corticosterone in the Hypothalamic Paraventricular Nucleus (PVN) on Stress-Induced Adrenocorticotrophic Hormone Secretion and Gene Expression in the PVN and Anterior Pituitary

Endogenous glucocorticoid negative-feedback influence on the hypothalamic-pituitary-adrenal (HPA) axis depends on glucocorticoid actions exerted on multiple glucocorticoid-sensitive tissues and differential glucocorticoid effects that are expressed within several distinct temporal domains. The relative contribution and underlying molecular mechanisms of action for the effects of location and timing of glucocorticoid exposure on HPA axis activity remain to be determined. In the present study, we examined the effects of acute exposure to corticosterone (CORT) at the level of the paraventricular nucleus (PVN) on the HPA axis response to a subsequent stressor in a short-term (1 h) timeframe. Intra-PVN CORT microinjection 1 h before restraint suppressed the adrenocorticotrophic hormone (ACTH) response and blunted restraint-induced corticotrophin-releasing hormone (CRH) heterogeneous nuclear (hn)RNA expression in the PVN and pro-opiomelanocortin hnRNA expression in the anterior pituitary (AP); however, it had no effect on restraint-induced plasma prolactin levels and c-fos mRNA expression (PVN and AP). This pattern of results suggests that CORT acts locally at the level of the PVN within a short-term timeframe to suppress stress-induced excitation-exocytosis coupling within CRH neurones and CRH gene induction without altering the stress-associated trans-synaptic input and intracellular signal transduction that converges on PVN c-fos gene induction. The present study is the first to demonstrate that an acute infusion of CORT into the PVN is sufficient to suppress the ACTH response to stress initiated 1 h after CORT infusion.

Effects of Mixture of Citri Peticulatae Viride Pericarpium and Lycii Radicis Cortex on the Change of HPA-Axis and Catecholamic System in the Forced Swimming Test

ABSTRACT Objectives：In this study the antidepressant effects of mixture of Citri Peticulatae Viride Pericarpium and Lycii Radicis Cortex on the change of HPA-Axis and Catecholamic system was investigatedMethods：The forced swimming test(FST) was performed. The expression of corticotropin-releasing factor(CRF), c-Fos in the paraventricular nucleus(PVN), and tyrosine hydroxylase(TH) in the ventral tegmental area(VTA) and locus coeruleus(LC) was measured with immunohistochemical method and the concentration of seum adrenocorticotropic hormone(ACTH) was measured with ELISA method. And the experimental groups were divided into the extraction after mixing(A) and mixture after extraction(B). The effects of both group were compared. Results：The duration of immobility in the forced swimming test was significantly decreased in the A400 group(P<0.01). The expression of CRF in PVN were significantly reduced in the A100, A400, B100, B400groups(P<0.001). but the expression of c-fos in PVN weren't reduced in all groups. And the concentration of ACTH in Plasma were significantly reduced in the A 100 group(P<0.01). The expression of TH in LC were significantly reduced in the A 400, B 100 and B400 groups(P<0.05~P<0.01). Conclusion：Mixture of Citri Peticulatae Viride Pericarpium and Lycii Radicis Cortex has antidepressant effects. But the difference between mixing and extracting methods was not shown.Key words：Mixture of Citri Peticulatae Viride Pericarpium and Lycii Radicis Cortex, FST, HPA Axis system, Catecholaminergic system, antidepressant.

Bed nucleus of the stria terminalis subregions differentially regulate hypothalamic-pituitary-adrenal axis activity: implications for the integration of limbic inputs.

Limbic and cortical neurocircuits profoundly influence hypothalamic-pituitary-adrenal (HPA) axis responses to stress yet have little or no direct projections to the hypothalamic paraventricular nucleus (PVN). Numerous lines of evidence suggest that the bed nucleus of the stria terminalis (BST) is well positioned to relay limbic information to the PVN. The BST comprises multiple anatomically distinct nuclei, of which some are known to receive direct limbic and/or cortical input and to heavily innervate the PVN. Our studies test the hypothesis that subregions of the BST differentially regulate HPA axis responses to acute stress. Male Sprague Dawley rats received bilateral ibotenate lesions, targeting either the principal nucleus in the posterior BST or the dorsomedial/fusiform nuclei in the anteroventral BST. Posterior BST lesions elevated plasma ACTH and corticosterone in response to acute restraint stress, increased stress-induced PVN c-fos mRNA, and elevated PVN corticotropin-releasing hormone (CRH) and parvocellular arginine vasopressin (AVP) mRNA expression relative to sham-lesion animals. In contrast, anterior BST lesions attenuated the plasma corticosterone response and decreased c-fos mRNA induction in the PVN but did not affect CRH and parvocellular AVP mRNA expression in the PVN. These data suggest that posterior BST nuclei are involved in inhibition of the HPA axis, whereas the anteroventral BST nuclei are involved in HPA axis excitation. The results indicate that the BST contains functional subdomains that play different roles in integrating and processing limbic information in response to stress and further suggest that excitatory as well as inhibitory limbic information is funneled through these important cell groups.

Acetaldehyde, a Major Constituent of Tobacco Smoke, Enhances Behavioral, Endocrine, and Neuronal Responses to Nicotine in Adolescent and Adult Rats

We have previously shown that acetaldehyde, a constituent of tobacco smoke, increases nicotine self-administration in adolescent, but not adult, rats. The aim of this study was to determine whether acetaldehyde influences other behavioral, endocrine, or neuronal responses to nicotine at either age. Juvenile (postnatal day (P) 27) and adult (P90) male Sprague-Dawley rats were treated with saline, acetaldehyde (16 microg/kg/injection x 2, i.v.), nicotine (30 microg/kg/injection x 2, i.v.) or a combination of acetaldehyde and nicotine. Locomotion and center time were evaluated for 30 min in a novel open field, before measurement of plasma corticosterone levels and brain c-fos mRNA. Nicotine increased locomotor activity in juveniles but decreased it in adults; in contrast, center time was increased at both ages. Acetaldehyde potentiated nicotine's locomotor effects, but not center time. Nicotine induced c-fos expression in the bed nucleus of the stria terminalis, the central nucleus of the amygdala (CeA), nucleus accumbens, and the superior colliculus (SC) at both ages, whereas it activated the hypothalamic paraventricular nucleus (PVN) and consequent corticosterone secretion only in adults. Acetaldehyde potentiated nicotine-induced c-fos in CeA and SC, and activation of PVN c-fos expression/plasma corticosterone release; however, this drug interaction was only observed in behaviorally tested animals, not those that were minimally stressed. Thus, acetaldehyde may modulate the interaction of nicotine and stress. Although pharmacokinetic studies showed that acetaldehyde did not change nicotine levels in either brain or serum, nicotine penetration into the brain was slower in juveniles as compared to adults.

Brain Localization and c‐Fos Activation of Histamine H3 Receptor Antagonists

We have previously shown that several H3 receptor (H3R) antagonists such as ABT-239 [4-(2-{2-[(2R)-2-methylpyrrolidinyl]-ethyl}-benzofuran-5-yl)-benzonitrile] enhance cognitive behavior whereas H3R antagonists like A-331440 [4′-[3-(3(R)-(dimethylamino)-pyrrolidin-1-yl)-propoxy]-biphenyl-4-carbonitrile] have antiobesity properties. Several hypotheses were explored in an attempt to reliably differentiate these activities including examining the differential localization of the H3R antagonists to discrete rat brain regions and evaluating the degree of c-FOS activation in various brain regions. Neither ABT-239 nor A-331440 demonstrated brain region specific localization. ABT-239 (1.0 mg/kg, i.v.) and A-331440 (5 mg/kg, i.v.) accessed rat frontal cortex, hippocampus, striatum, and hypothalamus within 1 hr at levels of 3.0, 2.8, 2.8, and 1.9 mg/gm and 23, 13.5, 14, and 11.5 mg/gm brain tissue homogenate, respectively, as quantified with mass spectrometry using deuterated analogs of each compound as internal standards. Both ABT-239 (3 and 30 mg/kg, i.p.) and A-331440 (1 and 30 mg/kg, i.p.) induced c-fos expression in the rat hypothalamic paraventricular nucleus (PVN), cingulate cortex, and hippocampal CA1, CA2/3, dentate regions 2 hr after administration. However, ABT-239 induced the greatest increases in c-fos expression in the hippocampal regions whereas A-331440 caused greatest induction in the hypothalamic PVN. Activation of c-fos in PVN, but not other regions, may differentiate antiobesity compounds such as A-331440 from procognitive leads such as ABT-239, which appears to primarily increase c-fos activity in areas associated with learning, in addition to activation in PVN. Research supported by Abbott Laboratories.

Cycloheximide prevents inhibition of expression of immediate early gene c-fos in paraventricular nuclei of rat hypothalamus produced by delta sleep-inducing peptide.

We studied expression of the immediate early gene c-fos in hypothalamic paraventricular nuclei in rats with different prognostic resistance to emotional stress receiving delta-sleep-inducing peptide after intracerebroventricular administration of cycloheximide. Delta-sleep-inducing peptide inhibited expression of the c-fos gene in rats receiving intracerebroventricular injection of physiological saline. Pretreatment with the protein synthesis blocker cycloheximide abolished changes produced by delta-sleep-inducing peptide.

Enhanced central response to dehydration in mice lacking angiotensin AT(1a) receptors.

The objective was to determine the central nervous system (CNS) responses to dehydration (c-Fos and vasopressin mRNA) in mice lacking the ANG AT(1a) receptor [ANG AT(1a) knockout (KO)]. Control and AT(1a) KO mice were dehydrated for 24 or 48 h. Baseline plasma vasopressin (VP) was not different between the groups; however, the response to dehydration was attenuated in AT(1a) KO (24 +/- 11 vs. 10.6 +/- 2.7 pg/ml). Dehydration produced similar increases in plasma osmolality and depletion of posterior pituitary VP content. Neuronal activation was observed as increases in c-Fos protein and VP mRNA. The supraoptic responses were not different between groups. In the paraventricular nucleus (PVN), c-Fos-positive neurons (57.4 +/- 10.7 vs. 98.4 +/- 7.4 c-Fos cells/PVN, control vs. AT(1a) KO) and VP mRNA levels (1.0 +/- 0.1 vs. 1.4 +/- 0.1 microCi, control vs. AT(1a) KO) were increased with greater responses in AT(1a) KO. A comparison of 1- to 2-day water deprivation showed that plasma VP, brain c-Fos, and VP mRNA returned toward control on day 2, although plasma osmolality remained high. Data demonstrate that AT(1a) KO mice show a dichotomous response to dehydration, reduced for plasma VP and enhanced for PVN c-Fos protein and VP mRNA. The results illustrate the importance of ANG AT(1a) receptors in the regulation of osmotic and endocrine balance.

Hormonal control of the reaction of the palmar sweat index to emotional stress

Chronic stress is often associated with a dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which can greatly increase risk for a number of stress-related diseases, including neuropsychiatric disorders. Despite a striking sex-bias in the prevalence of many of these disorders, few preclinical studies have examined female subjects. Hence, the present study aimed to explore the effects of chronic stress on the basal and acute stress-induced activity of the HPA axis in the female C57BL/6 mouse. We used a chronic variable stress (CVS) paradigm in these studies, which successfully induces physiological and behavioral changes that are similar to those reported for some patients with mood disorders. Using this model, we found pronounced, time-dependent effects of chronic stress on the HPA axis. CVS-treated females exhibited adrenal hypertrophy, yet their pattern of glucocorticoid secretion in the morning resembled that of controls. CVS-treated and control females had similar morning basal corticosterone (CORT) levels, which were both significantly elevated following a restraint stressor. Although morning basal gene expression of the key HPA-controlling neuropeptides corticotropin releasing hormone (CRH), arginine vasopressin (AVP) and oxytocin (OT) was unaltered within the paraventricular nucleus (PVN) by CVS, CVS altered the PVN OT and AVP mRNA responses to acute restraint. In control females, acute stress decreased AVP, but not OT mRNA; whereas, in CVS females, it decreased OT, but not, AVP mRNA. Unlike the morning pattern of HPA activity, in the evening, CVS-treated females showed increased basal CORT with hypoactive responses of CORT and PVN c-Fos immunoreactivity to restraint stress. Furthermore, CVS elevated evening PVN CRH and OT mRNAs in the PVN, but it did not influence anxiety- or depressive-like behavior after a light/dark box or tail suspension test. Taken together, these findings indicate that CVS is an effective model for HPA axis dysregulation in the female mouse and may be relevant for stress-related diseases.