scholarly journals Hypothalamic-pituitary-adrenal axis up-regulation in rats submitted to pituitary stalk compression

2004 ◽  
Vol 180 (2) ◽  
pp. 297-302 ◽  
Author(s):  
PC Elias ◽  
LL Elias ◽  
M Castro ◽  
J Antunes-Rodrigues ◽  
AC Moreira
Keyword(s):  
Hpa Axis ◽  
Water Intake ◽  
Immobilization Stress ◽  
Male Rats ◽  
Pituitary Stalk ◽  
Salt Loading ◽  
Hypothalamic Pituitary Adrenal ◽  
Salt Load ◽  
Post Surgery

The present study investigated the hypothalamic-pituitary-adrenal (HPA) axis activity in response to stress in adult male rats submitted to pituitary stalk compression (PSC) or sham operation. Animals received water or oral salt loading (2% NaCl) for one or eight days before the day of the experiment. On the 14th day post-surgery rats were killed under basal conditions or after 15 min immobilization stress. In the PSC group urine output increased significantly and plasma vasopressin (AVP) levels failed to respond to osmotic stimuli. Short-term salt load induced a significant increase in AVP levels in the sham-operated group. The PSC group presented higher adrenocorticotrophin (ACTH) and corticosterone levels compared with sham-operated rats, both in water intake and salt load conditions. Immobilization stress induced a similar increase in plasma ACTH and corticosterone concentrations in sham-operated and PSC groups under water intake. However, long-term salt load blunted the ACTH and corticosterone responses to immobilization stress in sham-operated rats. PSC rats submitted to short- and long-term salt loading presented no changes in ACTH and corticosterone levels after immobilization. Immobilization stress caused neither AVP responses nor plasma osmolality changes in sham and PSC groups. There was no difference in median eminence AVP content among all groups. In conclusion, the high ACTH and corticosterone levels found in PSC rats under water intake and salt loading conditions suggest an up-regulation of the HPA axis, with a preserved adaptive mechanism to chronic stress.

Long-term basal and dynamic evaluation of hypothalamic-pituitary-adrenal (HPA) axis in acromegalic patients

2008 ◽  
Vol 69 (4) ◽  
pp. 608-612 ◽  
Author(s):  
C. L. Ronchi ◽  
E. Ferrante ◽  
E. Rizzo ◽  
C. Giavoli ◽  
E. Verrua ◽  
...  
Keyword(s):  
Hpa Axis ◽  
Hypothalamic Pituitary Adrenal ◽  
Dynamic Evaluation

scholarly journals Hypoactivity of the Hypothalamo-Pituitary-Adrenocortical Axis during Recovery from Chronic Variable Stress

Endocrinology ◽  
2006 ◽  
Vol 147 (4) ◽  
pp. 2008-2017 ◽  
Author(s):  
Michelle M. Ostrander ◽  
Yvonne M. Ulrich-Lai ◽  
Dennis C. Choi ◽  
Neil M. Richtand ◽  
James P. Herman
Keyword(s):  
Mrna Expression ◽  
Chronic Stress ◽  
Hpa Axis ◽  
Male Rats ◽  
Plasma Acth ◽  
Novel Environment ◽  
Systemic Hypoxia ◽  
Delayed Recovery ◽  
Chronic Variable Stress

Chronic stress induces both functional and structural adaptations within the hypothalamo-pituitary-adrenocortical (HPA) axis, suggestive of long-term alterations in neuroendocrine reactivity to subsequent stressors. We hypothesized that prior chronic stress would produce persistent enhancement of HPA axis reactivity to novel stressors. Adult male rats were exposed to chronic variable stress (CVS) for 1 wk and allowed to recover. Plasma ACTH and corticosterone levels were measured in control or CVS rats exposed to novel psychogenic (novel environment or restraint) or systemic (hypoxia) stressors at 16 h, 4 d, 7 d, or 30 d after CVS cessation. Plasma ACTH and corticosterone responses to psychogenic stressors were attenuated at 4 d (novel environment and restraint) and 7 d (novel environment only) recovery from CVS, whereas hormonal responses to the systemic stressor were largely unaffected by CVS. CRH mRNA expression was up-regulated in the paraventricular nucleus of the hypothalamus (PVN) at 16 h after cessation of CVS, but no other alterations in PVN CRH or arginine vasopressin mRNA expression were observed. Thus, in contrast to our hypothesis, reductions of HPA axis sensitivity to psychogenic stressors manifested at delayed recovery time points after CVS. The capacity of the HPA axis to respond to a systemic stressor appeared largely intact during recovery from CVS. These data suggest that chronic stress selectively targets brain circuits responsible for integration of psychogenic stimuli, resulting in decreased HPA axis responsiveness, possibly mediated in part by transitory alterations in PVN CRH expression.

The influence of long-term melatonin administration on basic physiological and metabolic variables of young Wistar:Han rats

Biologia ◽  
2006 ◽  
Vol 61 (3) ◽  
Author(s):  
Monika Kassayová ◽  
Martina Marková ◽  
Bianka Bojková ◽  
Eva Adámeková ◽  
Peter Kubatka ◽  
...  
Keyword(s):  
Body Weight ◽  
Water Intake ◽  
Glucose Concentration ◽  
Tap Water ◽  
Serum Glucose ◽  
The Body ◽  
Male Rats ◽  
Epididymal Fat ◽  
Food And Water Intake

AbstractThe question of effects of long-term melatonin (MEL) administration have not yet been explained sufficiently, especially its metabolic consequences in young persons and animals. The aim of the present study was to analyze the effects of MEL given during prolonged time (for 3 months) and chronically (for 6 months) at the dose of 4 µg/mL of tap water, on the selected metabolic and hormonal parameters in young female and male Wistar:Han (WH) rats. The weights of selected organs, tissues, body weight gains and food and water intake were registered. Six weeks aged rats were adapted to standard housing conditions and light regimen L:D=12:12 h, fed standard laboratory diet and drank tap water (controls) or MEL solution ad libitum; finally they were sacrificed after overnight fasting. Prolonged MEL administration decreased serum glucose concentration and increased triacylglycerol and malondialdehyde concentration/content in the liver in females. In males MEL increased concentrations of serum phospholipids, corticosterone and liver malondialdehyde. MEL treatment reduced the body weight in both sexes and weight of epididymal fat in males, without any alterations of food and water intake. Chronic MEL administration reduced serum glucose concentration and increased concentration/content of glycogen, triacylglycerol and cholesterol in the liver and glycogen concentration/content in heart muscle in males. In females, the significant rise of serum corticosterone concentration and liver malondialdehyde content was recorded. MEL significantly increased liver weight and decreased thymus weight in males. MEL administration increased temporarily water intake in males, body and epididymal fat weights were similar to that in controls. Body weight of MEL drinking females was reduced in the 1st half of experiment only; the food and water intake did not differ from control group. The response in WH rats on MEL was more prominent as in the Sprague-Dawley strain (our previous studies). Male rats were generally more affected, probably due to higher daily and total consumption of melatonin.

scholarly journals Regulation of the Hypothalamic-Pituitary-Adrenal Axis Circadian Rhythm by Endocannabinoids Is Sexually Diergic

Endocrinology ◽  
2010 ◽  
Vol 151 (8) ◽  
pp. 3720-3727 ◽  
Author(s):  
Helen C. Atkinson ◽  
James D. Leggett ◽  
Susan A. Wood ◽  
Emma S. Castrique ◽  
Yvonne M. Kershaw ◽  
...  
Keyword(s):  
Hpa Axis ◽  
Cannabinoid Receptor ◽  
Time Of Day ◽  
Female Rats ◽  
Male Rats ◽  
Acute Administration ◽  
Sampling System ◽  
Hypothalamic Pituitary Adrenal ◽  
Male And Female Rats ◽  
Cb1 Antagonist

We have examined the effects of acute administration of the cannabinoid receptor type 1 (CB1) antagonist AM251 on the rat hypothalamic-pituitary-adrenal (HPA) axis with respect to both gender and time of day. Blood samples were collected from conscious male and female rats every 5 min using an automated blood sampling system, and corticosterone concentrations were determined. In male rats, there was a distinct diurnal effect of AM251 with a greater activation of the HPA axis in the morning (diurnal trough) compared with the evening (diurnal peak). At both times of the day, circulating corticosterone concentrations were elevated for approximately 4 h after AM251 administration. In female rats, there was also diurnal variation in the activation of the HPA axis; however, these effects were not as profound as those in males. Corticosterone concentrations were only slightly elevated at the diurnal trough and for a shorter time period than in males (2 compared with 4 h). Moreover, there was no effect of AM251 on corticosterone concentrations when administered at the diurnal peak. Subsequent studies, only in males, in which both ACTH and corticosterone were measured, confirmed that the effects of AM251 on corticosterone were mediated by ACTH. Moreover, the elevation of both ACTH and corticosterone could be replicated using another CB1 antagonist, AM281. These data demonstrate that the extent and duration of HPA axis activation after CB1 blockade are clearly dependent on both gender and time of day.

Prenatal exposure to dexamethasone alters hippocampal drive on hypothalamic-pituitary-adrenal axis activity in adult male rats

2006 ◽  
Vol 290 (5) ◽  
pp. R1366-R1373 ◽  
Author(s):  
Jennifer A. Shoener ◽  
Romana Baig ◽  
Kathleen C. Page
Keyword(s):  
Hpa Axis ◽  
Adult Male ◽  
Restraint Stress ◽  
Exposed Group ◽  
Late Gestation ◽  
Male Rats ◽  
Mrna Levels ◽  
Hypothalamic Pituitary Adrenal ◽  
Hpa Axis Activity ◽  
Circulating Levels

Glucocorticoids are essential for normal hypothalamic-pituitary-adrenal (HPA) axis activity; however, recent studies warn that exposure to excess endogenous or synthetic glucocorticoid during a specific period of prenatal development adversely affects HPA axis stability. We administered dexamethasone (DEX) to pregnant rats during the last week of gestation and investigated subsequent HPA axis regulation in adult male offspring in unrestrained and restraint-stressed conditions. With the use of real-time PCR and RIA, we examined the expression of regulatory genes in the hippocampus, hypothalamus, and pituitary, including corticotropin-releasing hormone (CRH), arginine vasopressin (AVP), glucocorticoid receptors (GR), mineralcorticoid receptors (MR), and 11-β-hydroxysteroid dehydrogenase-1 (11β-HSD-1), as well as the main HPA axis hormones, adrenal corticotropic hormone (ACTH) and corticosterone (CORT). Our results demonstrate that the DEX-exposed group exhibited an overall change in the pattern of gene expression and hormone levels in the unrestrained animals. These changes included an upregulation of CRH in the hypothalamus, a downregulation of MR with a concomitant upregulation of 11β-HSD-1 in the hippocampus, and an increase in circulating levels of both ACTH and CORT relative to unrestrained control animals. Interestingly, both DEX-exposed and control rats exhibited an increase in pituitary GR mRNA levels following a 1-h recovery from restraint stress; however, the increased expression in DEX-exposed rats was significantly less and was associated with a slower return to baseline CORT compared with controls. In addition, circulating levels of ACTH and CORT as well as hypothalamic CRH and hippocampal 11β-HSD-1 expression levels were significantly higher in the DEX-exposed group compared with controls following restraint stress. Taken together, these data demonstrate that late-gestation DEX exposure in rats is associated with persistent changes in both the modulation of HPA axis activity and the HPA axis-mediated response to stress.

scholarly journals Voluntary wheel running initially increases adrenal sensitivity to adrenocorticotrophic hormone, which is attenuated with long-term training

2009 ◽  
Vol 106 (1) ◽  
pp. 66-72 ◽  
Author(s):  
Jonathan E. Campbell ◽  
Nasimeh Rakhshani ◽  
Sergiu Fediuc ◽  
Silvio Bruni ◽  
Michael C. Riddell
Keyword(s):  
Stress Response ◽  
Hpa Axis ◽  
Restraint Stress ◽  
Acute Stress ◽  
Wheel Running ◽  
Male Rats ◽  
Voluntary Wheel Running ◽  
Acute Stress Response ◽  
Voluntary Wheel

Although exercise is a common and potent activator of the hypothalamic-pituitary adrenal (HPA) axis, the effects of exercise on the acute stress response are not well understood. Here, we investigated the effects of short- (2 wk) and long-term (8 wk) voluntary wheel running on adrenal sensitivity to ACTH stimulation and the acute stress response to restraint in male rats. Diurnal glucocorticoid patterns were measured on days 7 (all groups) and 35 (8-wk groups). Rats were subjected to 20 min of restraint stress on either week 1 or on week 7 of treatment to assess HPA activation. One week later, exogenous ACTH (75 ng/kg) was administered to assess adrenal sensitivity to ACTH. Following this, adrenals were collected and analyzed for key proteins involved in corticosterone (CORT) synthesis. By the end of week 1, exercising (E) animals had twofold higher peak diurnal CORT levels compared with sedentary (S) animals ( P < 0.01). CORT values were not different between groups at week 8. In response to restraint stress at week 2, CORT values in E were approximately threefold greater than in S ( P < 0.05). No difference was found between E and S rats in the response to, or recovery from, restraint at week 8. During the ACTH challenge at week 2, E demonstrated a ∼2.5-fold increase in adrenal sensitivity compared with S, while no difference was found between E and S at week 8. The expression of steroidogenic acute regulatory protein was found to be ∼50% higher in the adrenals in E compared with S at week 2 ( P < 0.05), but no difference existed between groups at week 8. These results show that volitional wheel running initially causes hyperactivation of the HPA axis, due to enhanced adrenal sensitivity to ACTH, but that these alterations in HPA activity are completely restored by 8 wk of training.

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