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Query: UMLS:C0848237 (acute stress)
 4,619 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of previous chronic ACTH administration on the physiological response to acute and chronic immobilization stress was studied in adult male rats. Chronic ACTH administration slightly reduced food intake and drastically inhibited body weight gain. Serum corticosterone levels were similar in saline- and ACTH-treated rats twenty hours after the last administration. However, the corticosterone response to 1 hr immobilization was greatly reduced by previous ACTH administration. When the exposure to the stressor was prolonged up to 18 hours, the corticosterone response was similar in saline, and ACTH-treated rats. While body weight loss caused by starvation and acute stress was lower in ACTH-treated rats, stomach ulceration was greater in the latter animals. Although ACTH-treated rats showed higher body weight gain than saline-treated animals during chronic immobilization, this was probably due to catch-up growth as food intake inhibition caused by the stressor was similar in the two groups. Pituitary-adrenal adaptation to the repeated stressor was the same in saline- and ACTH-treated rats. Therefore, the effects of previous ACTH treated on the physiological response to either acute or chronic stress appear to be mixed, depending on the variable studied.
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PMID:Previous chronic ACTH administration does not protect against the effects of acute or chronic stress in male rats. 281 6

Chronic confinement for 1 month caused a significant elevation of plasma cortisol but suppressed the levels of plasma testosterone and 11-ketotestosterone in sexually mature male brown trout. An acute handling stress for 1 hr elevated blood cortisol and ACTH levels and also suppressed circulating androgens. This androgen suppression in response to acute stress was accompanied by an elevation of plasma gonadotropin levels. These findings are discussed in relation to stress-induced suppression of reproductive function in mammals and the possible biological consequences of such a suppression in fish are outlined.
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PMID:The effects of acute and chronic stress on the levels of reproductive hormones in the plasma of mature male brown trout, Salmo trutta L. 282 50

To study the effect of acute stress on ACTH secretion and synthesis in rat pituitary and hypothalamus, ACTH content and POMC mRNA levels (measured by use of Northern blot analysis) in these tissues as well as the levels of ACTH in plasma and those of CRF in the hypothalamus were determined after insulin-induced hypoglycemia. Plasma ACTH levels increased at 30 and 60 min. ACTH levels in the anterior pituitary lobe (AP) decreased at 30 min, and then returned to control levels at 60 min. No change was seen in the intermediate-posterior pituitary (IP) or the hypothalamus after insulin injection. CRF levels decreased at 30 and 60 min, then returned to control levels at 90 min in the medial basal hypothalamus, including the median eminence. Hybridization with a cDNA probe revealed a single size class of POMC mRNA in AP, IP, and hypothalamus, and the size of POMC mRNA in these tissues did not change during the experimental period. POMC mRNA levels in AP increased at 60 min and reached a peak at 120 min, but those in IP and hypothalamus did not change. These results suggest that 1) insulin-induced hypoglycemia stimulates both secretion and synthesis of ACTH (at least by increasing POMC mRNA levels) in the AP, and 2) the levels of ACTH and POMC mRNA in the IP and hypothalamus are not affected by insulin-induced hypoglycemia.
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PMID:Insulin-induced hypoglycemia increases proopiomelanocortin messenger ribonucleic acid levels in rat anterior pituitary gland. 283 Oct 25

Rats sacrificed after 4 days in the activity-stress paradigm or after 4 days of food restriction had significantly elevated levels of plasma corticosterone as compared to control rats. The approximately 5 fold increase in corticosterone in the stressed treatment groups was consistently found in all experiments. ACTH levels were elevated in activity-stress and food-restricted groups in some experiments but these increases were not statistically significant. Prolactin levels were significantly elevated in food-restricted group rats as compared to controls or activity-stress group animals in one experiment but this finding was not repeated in further experiments. In a second series of experiments, rats from activity-stressed and food-restricted treatment groups and controls were exposed to an acute stressor for 15 min prior to sacrifice to assess the effects of prior sustained stress on hormonal responses to an acute stressor. Exposure to 15 min of immobilization or intermittent footshock immediately prior to sacrifice increased plasma levels of corticosterone, ACTH and prolactin in control, food-restricted and activity-stressed rats. Generally, hormonal responses to the acute stress were similar in all treatment groups. However, in two experiments where the resting levels of corticosterone were especially elevated in the activity-stress group, the acute stress-induced rise in corticosterone was less than that seen for the other two treatment groups. In another experiment, administration of dexamethasone suppressed acute stress-evoked levels of ACTH and corticosterone in control, activity-stressed and food-restricted rats. Thus, rats exposed to 4 days of sustained stress were found to have consistently elevated resting levels of corticosterone.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Neuroendocrine correlates of sustained stress: the activity-stress paradigm. 283 25

To study the effect of acute stress on CRF release and synthesis in rat hypothalamus, ACTH levels in plasma, CRF contents in the median eminence (ME), and CRF mRNA levels in the hypothalamus without ME and cerebral cortex were determined after insulin-induced hypoglycemia. Plasma ACTH levels increased at 30 and 60 min, while ME CRF content decreased at 30 and 60 min, then returned to the control level at 90 min. Hybridization with a cRNA probe revealed a single size class of CRF mRNA in the hypothalamus and cerebral cortex (approximately 1300 nucleotides), and the size of CRF mRNA in these tissues did not change during the experimental period. CRF mRNA levels in the hypothalamus increased to 130% of the control value at 30 min and reached a peak (186% of the control value) at 120 min, but these levels in the cerebral cortex did not change. These results suggest that insulin-induced hypoglycemia stimulates CRF synthesis by increasing CRF mRNA levels in the hypothalamus as well as CRF release, and that release and synthesis of CRF in the cerebral cortex are independent of those in the hypothalamus.
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PMID:Insulin-induced hypoglycemia increases corticotropin-releasing factor messenger ribonucleic acid levels in rat hypothalamus. 284 Oct 92

An acute form of "stress-analgesia" is evoked by allowing the smoke of a cigarette to envelope the nostrils of unanaesthetized rabbits. The response consists of an immediate and generalized arrest of spontaneous movements, including respiration and expiration, reduced muscular tone, and unresponsiveness to pinching. This motor "paralysis" is accompanied by a profound bradycardia. Attempts have been made to identify the neurotransmitters involved in "the smoke reflex" by the intervention of antagonists and psychopharmaca. The bradycardia was selectively blocked by atropine, leaving the somatomotor inhibition unaltered. All components of the response were abolished by approximately 60% by clonidine and by 40% by the tricyclic antidepressant amitriptyline, both of which are known to attenuate the release of noradrenaline as agonsits of alpha 2-adrenoceptors. Yohimbine blocked the clonidine effect. Naloxone (1-2 mg/kg), p-chlorphenylalanine and dexamethasone failed to influence the reflex response, suggesting that opiate, serotonergic and ACTH-systems do not play a critical role. The same applied to the benzodiazepine chlordiapoxide. The results suggest that this acute stress-induced analgesia is mediated via a noradrenergic system. The relationship of the smoke reflex to "the fear paralysis reflex", a possible trigger mechanism for the sudden infant death syndrome, is discussed.
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PMID:Neurotransmitters in "the smoke reflex" in rabbits. 288 36

In addition to corticotropin-releasing factor (CRF) and structurally related peptides, arginine vasopressin (AVP), oxytocin, angiotensin II, vasoactive intestinal polypeptide, peptide histidine isoleucinamide, epinephrine (E), and norepinephrine induce secretion of adrenocorticotropin (ACTH) from corticotropic cells in vitro. The apparent affinity and intrinsic ACTH-releasing activity of these substances are lower than those of CRF. These substances can also act synergistically with CRF. In this paper the role of catecholamines and AVP in the control of ACTH release is discussed. Infusion i.v. of E increases plasma ACTH and corticosterone to levels that are normally found during stress. E-induced stimulation of pituitary-adrenal activity is mediated by beta adrenoceptors and involves release of CRF, because it can be prevented by beta-adrenoceptor blockers and by destruction of CRF neurons (hypothalamic lesions), blockade of CRF release (chlorpromazine, morphine, and Nembutal), or administration of CRF antiserum. Although stress can cause a vast increase in plasma E, circulating E is not essential for the acute stress-induced release of ACTH because blockade of beta (or alpha) adrenoceptors, administration of chlorisondamine, or extirpation of the adrenal medulla and sympathectomy do not prevent the pituitary-adrenal response to stress. In contrast, circulating E plays a major role in the release of intermediate-lobe peptides during emotional stress. Studies of the role of AVP in pituitary-adrenal control by the use of pressor receptor (V1) antagonists are not valuable because of the ineffectiveness of such antagonists in blocking AVP-induced release of ACTH from corticotropic cells in vitro. Treatment of rats with an antiserum to AVP reduces the ACTH response to stress. We conclude that AVP has an important role in stress-induced activation of the pituitary-adrenal system, possibly by potentiating the effects of CRF.
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PMID:Role of epinephrine and vasopressin in the control of the pituitary-adrenal response to stress. 298 37

The effects of acute and chronic stress on the release of ACTH and beta-endorphin in response to stimulation by ovine corticotropin-releasing factor (CRF) and arginine vasopressin were examined. Pituitaries were removed from rats who had received either acute stress, chronic stress daily for 14 days with the last stress occurring 24 h before decapitation, or chronic stress followed by an acute stress immediately before decapitation (chronic stress-acute stress). Pituitaries from naive unstressed animals were used as the control group. After processing into single cell suspensions, the pituitaries were incubated with various doses of CRF (10(-11) M to 10(-9) M) and AVP (10(-10) M to 10(-8) M). Release of ACTH and beta-endorphin into the medium was measured by RIA. A clear dose-dependent response to both releasers was seen in control pituitaries. In acute stress, a decreased responsiveness to arginine vasopressin and CRF was seen. This same blunted response was not seen in chronic stress even if the animals are stressed immediately before decapitation. At higher doses of CRF (10(-9) M) a substantially increased release of ACTH and beta-endorphin was seen in the chronically stressed rats. When the content of the anterior pituitary lobe was assayed in these animals, both chronic stress groups show increased content of ACTH and beta-endorphin, which may indicate an increase amount of ACTH and beta-endorphin in the releasable pools in chronic stress. In addition, the failure of further stress to alter the response to CRF in the chronic stress-acute stress group may indicate a down-regulation of the steroid feedback on the pituitary. However, it is clear that no down-regulation of the CRF receptor occurs in this chronic stress paradigm.
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PMID:Corticotropin-releasing factor stimulation of adrenocorticotropin and beta-endorphin release: effects of acute and chronic stress. 298 16

Patients recovering from acute surgical stress often excrete increased 17-OH corticosteroids with no change in 17-ketosteroids. The explanation for these findings is unclear. In order to investigate possible divergence between cortisol and adrenal androgen metabolism in acute stress, repeated morning cortisol and dehydroepiandrosterone (DHA) measurements were made in patients undergoing ACTH stimulation 48 to 96 hours preoperatively, followed by determinations before and during major surgery, also performed in the morning. Cortisol and DHA are largely metabolized by the liver, so liver blood flow under a constant general anesthetic regimen known not to affect cortisol metabolism was monitored by pre- and intraoperative indocyanine green dye clearance. Results indicated no difference between the cortisol and DHA stimulation resulting from two hours of ACTH stimulation or major surgery, and a small (14.4%) decline in hepatic blood flow during general anesthesia. However, while DHA concentrations remained constant immediately preceding surgery, cortisol concentrations increased by 61% (P less than 0.05). Previous studies have also demonstrated increased concentrations of cortisol before surgical procedures, presumably due to psychological stress. However, this is the first demonstration of a dissociation between concentrations of cortisol and an adrenal androgen due to psychological stress.
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PMID:Dissociation of adrenal androgen and cortisol levels in acute stress. 298 40

Because some recent studies of hamster adrenocortical function have depended on older studies that may have been inadequate or misinterpreted, the present study re-examined plasma corticosterone and cortisol concentrations in hamsters under several conditions to determine which plasma glucocorticoid predominated in this animal. Sensitive radioimmunoassays were used to measure separately the two glucocorticoids in the basal condition, after adrenocorticotropin (ACTH) treatment, after acute stress, and after chronic stress. In the basal condition, corticosterone concentrations were 3-4 times higher than those of cortisol. After stimulation, this difference disappeared, but rarely were any hamster's cortisol levels higher than their corticosterone levels. Both ACTH and acute stress elevated plasma corticosterone and cortisol concentrations, but only plasma cortisol concentrations were elevated following chronic stress. The dissociation between cortisol and corticosterone concentrations after chronic stress suggests that the two glucocorticoid hormones in the hamster may be regulated independently. The data also indicate that both corticosterone and cortisol should be measured when assessing adrenocortical function in the hamster.
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PMID:Plasma cortisol and corticosterone concentrations in the golden hamster, (Mesocricetus auratus). 299 49


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