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

Male rough-skinned newts (Taricha granulosa) were used to investigate the hormonal responses associated with stress-induced inhibition of reproduction. When male newts were confined for 1 hr, using a procedure that previously had elicited physiological stress responses, androgen concentrations decreased in the plasma and immunoreactive (ir) LH-RH concentrations increased in the infundibulum and rostral hypothalamus. Likewise, when male newts were injected with 25 micrograms of corticosterone, androgen concentrations decreased and hypothalamic irLH-RH concentrations increased. These data, which are from experiments in February, support the hypothesis that in this amphibian, exposure to acute stress or to exogenous corticosterone can suppress plasma androgen titers by inhibiting the release of LH-RH from the hypothalamus. The effects of the confinement procedure and the injection of corticosterone on the concentrations of irLH-RH and androgens were different for newts in September than for newts in February.
Gen Comp Endocrinol 1985 Nov
PMID:Stress-induced inhibition of reproduction: evidence of suppressed secretion of LH-RH in an amphibian. 390 2

Plasma levels of corticosterone and aldosterone were determined by radioimmunoassay in ducks consuming diets containing different concentrations of sodium and potassium. Compared with control diet birds, maintenance on a high-Na+ diet for 5 days caused a 2-fold increase in the basal plasma corticosterone concentration, while adaptation for 8 days to a low-Na+ diet resulted in a 2.6-fold increase in the basal plasma concentration of aldosterone. Both corticosterone and aldosterone basal plasma levels were greatly elevated in birds denied access to drinking water for 4 days. Adaptation to a high-Na+ diet or deprivation of water resulted in hyperosmolality and hypernatremia, while the high-K+, low-Na+/low-K+, and low-Na+ diets did not significantly alter the plasma sodium or potassium levels from the control levels. In addition, birds were stressed by semi-immobilization to determine the effects of acute stress-induced ACTH secretion on the adrenocortical response following changes in dietary sodium and potassium intake. In ducks adapted to low-Na+/low-K+, high-Na+, and low-Na+ diets, stress-induced adrenocorticotrophic hormone (ACTH) increased the aldosterone, but not the corticosterone, response to a level significantly greater than in the controls. These results demonstrate that in the duck secretion of corticosterone and aldosterone can be independently regulated. Furthermore, the endocrine changes that are induced by altered sodium and potassium intake are reflected in the adrenocortical responses to acute stress.
Gen Comp Endocrinol 1985 Apr
PMID:Effects of chronic changes in dietary electrolytes and acute stress on plasma levels of corticosterone and aldosterone in the duck (Anas platyrhynchos). 398 30

Plasma somatolactin (SL) concentrations in rainbow trout were examined under various physiological and environmental conditions. Background adaptation and feeding did not affect plasma SL levels. There was no consistent change in plasma SL levels during fasting for 21 days, although increased plasma growth hormone levels and decreased condition factor, hepatosomatic index and abdominal fat, occurred. Plasma SL concentrations increased during acute stress and also during exhaustive exercise resulting from being chased in shallow water. Elevation of plasma SL was associated with those of plasma cortisol, Ca2+, phosphate, and glucose levels. On the other hand, plasma level of prolactin was not affected in the stress and exercise experiments, although plasma GH and Na+ were raised in the fish 5 min after the onset of the stress. Our results suggest the involvement of SL in calcium and phosphate metabolism, acid-base regulation, or energy mobilization in the stressed or exercised trout.
Gen Comp Endocrinol 1995 May
PMID:Effects of feeding, fasting, background adaptation, acute stress, and exhaustive exercise on the plasma somatolactin concentrations in rainbow trout. 763 67

The ontogeny of the interrenal stress response in rainbow trout was characterized by measuring resting and acute-stress-induced changes in whole-body cortisol levels in embryos and larvae at different early developmental stages. In Experiment 1, resting cortisol levels averaged 6.0 ng/g in newly fertilized eggs, fell to less than 0.3 ng/g by the time of hatching at Week 4 (incubation at 10 degrees), and increased to 1.4 ng/g by Week 5. Cortisol levels did not change in response to acute stress in 3-, 4-, or 5-week-old fish. In Experiment 2, resting cortisol averaged 1.4 ng/g in newly fertilized eggs, fell to less than 0.03 ng/g by Week 2, and then steadily increased between Weeks 3 and 6 to a peak of 4.8 ng/g before falling to 1.2 ng/g by Week 7. Cortisol levels did not change in response to acute stress in 3-, 4-, or 5-week-old fish. Six-week-old fish showed a 2.3-fold increase in cortisol levels at 1 hr poststress, indicating that the hypothalamic-pituitary-interrenal axis first develops responsiveness to stress 2 weeks after hatching and 1 week before the onset of exogenous feeding. The stress hyporesponsive period after hatching in rainbow trout may be homologous to the 2-week stress hyporesponsive period after birth in rodents, the function of which may be to maintain low, constant corticosteroid levels during a critical developmental period when these steroids can have permanent effects on neural organization. As suggested for mammals, this period may be a time when rainbow trout are particularly vulnerable to environmental effects on their subsequent development.
Gen Comp Endocrinol 1995 Jan
PMID:Ontogeny of the cortisol stress response in larval rainbow trout. 771 84

Postemergent salmonid fry experience a "critical period" in their development, during which there may be a high mortality rate, so determining the long-term success of the year class. The mechanism(s) underlying this phenomenon are not fully understood but physiological stress may be a contributory factor. This study sought to establish at what point in their development, posthatch, salmonids become stress responsive in terms of activation of the hypothalamic-pituitary-interrenal (HPI) axis. Immunoreactive corticosteroids were measured in tissue extracts of rainbow trout at intervals from 4 weeks prehatch to 27 weeks posthatch and in brown trout from 5 to 22 weeks posthatch. Corticosteroids were detectable throughout this period in both species. Simultaneous determination of whole-body immunoreactive corticosteroid levels (IRC) and plasma cortisol levels in fingerling trout validated the use of whole-body levels as an indicator of stress-induced elevation of corticosteroids. However, the dynamics of the circulating cortisol response to stress were not fully conveyed by whole-body measurements. From 5 weeks posthatch IRC increased significantly within 30-60 min following mechanical disturbance and confinement, suggesting a functional HPI axis to be present. An ectoparasite (Ichthyobodo sp.) infestation during this period caused a substantial increase in IRC levels in both species indicating that the HPI axis in these fish was sensitive to naturally occurring stressors. The response of fry to acute and chronic stress resembled that of adult fish in terms of duration. These data indicate that the early pre- and postemergent stages of salmonid fish are likely to be able to benefit from the adaptive advantage of HPI activation during episodes of acute stress but may also be susceptible to the deleterious consequences of prolonged activation of the HPI axis under conditions of chronic stress.
Gen Comp Endocrinol 1994 Sep
PMID:The corticosteroidogenic response of brown and rainbow trout alevins and fry to environmental stress during a "critical period". 782 71

We evaluated the adrenocortical response to acute stress in free-living Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii) using a standardized capture stress protocol in which five serial blood samples (70 microliters) were taken for measurement of plasma corticosterone (B) over the course of an hour of captivity (at 1, 5, 10, 30, and 60 min). In field-captured birds, male plasma B levels rose two to four times higher than those of females under capture stress during the breeding season, but were no different during winter (nonbreeding). We investigated the basis of this pattern by conducting dexamethasone (DEX) suppression tests on breeding and nonbreeding sparrows of both genders. This test involves pretreatment with subcutaneous DEX implants (a potent synthetic glucocorticoid) and challenge with intrajugular injections of either corticotropin (ACTH) or saline, followed by collection of a series of blood samples for evaluation of plasma B levels over a 2-hr period. ACTH injections in DEX-treated birds resulted in elevated B in both genders, with nonbreeding B profiles consistently lower than those of breeding birds. All DEX-treated, saline-injected birds, except breeding males, maintained low B levels for the entire 2-hr post-challenge period. This result indicates effective negative feedback by DEX on the hypothalamic-pituitary-adrenal axis, thus inhibiting endogenous B secretion. The apparent reduction in glucocorticoid feedback inhibition in breeding males may be related to an uncoupling of adrenal effects on reproductive behavior.
Gen Comp Endocrinol 1994 Apr
PMID:Gender and seasonal differences in the adrenocortical response to ACTH challenge in an arctic passerine, Zonotrichia leucophrys gambelii. 804 66

Interrenal tissue from embryonic and larval rainbow trout (Oncorhynchus mykiss) was cultured in vitro and exposed to various doses of adrenocorticotropin (ACTH) to document the ontogeny of interrenal responsiveness to tropic stimulation. Resting and acute stress-induced changes in whole-body cortisol levels in vivo were also measured to determine if the corticosteroid stress response first develops with the onset of interrenal responsiveness to ACTH. No evidence was found that the hypothalamic-pituitary-interrenal (HPI) axis of rainbow trout is transiently activated prior to hatching. In vivo, a corticosteroid stress response was first observed 2 weeks after hatching, and stress-induced cortisol levels (at 1 hr poststress) were significantly higher 3 weeks after hatching than they were at 2 or 4 weeks after hatching. In contrast, cultured interrenal tissue produced significant levels of cortisol in response to ACTH at the time of hatching, and in vitro cortisol production by the interrenal increased significantly between 3 and 4 weeks after hatching. Interrenal sensitivity to ACTH did not change appreciably with development. We conclude that (1) the final maturation of the corticosteroid stress response in rainbow trout occurs at the level of the brain and/or sensory inputs and not at the level of the interrenal cell; (2) negative feedback mechanisms within the HPI axis develop 3 to 4 weeks after hatching; and (3) the period between 3 and 4 weeks after hatching may be homologous to the stress hyporesponsive period after birth in mammals and thus could be a stage when environmental influences can permanently alter the development of the corticosteroid stress response in rainbow trout.
Gen Comp Endocrinol 1995 Sep
PMID:In vitro effects of ACTH on interrenal corticosteroidogenesis during early larval development in rainbow trout. 853 50

Somatolactin (SL), a recently identified teleost pituitary hormone which is a member of the growth hormone/prolactin family, was isolated from pituitary tissue of Atlantic halibut (Hippoglossus hippoglossus). Pituitary proteins were extracted in ammonium bicarbonate (pH 7.8), fractionated using gel filtration chromatography, and purified using reversed-phase high-performance liquid chromatography. Halibut SL was identified on the basis of molecular size (determined by gel electrophoresis and mass spectroscopy), cross-reactivity of the putative hormone with antisera to cod SL, and N-terminal amino acid sequence. Polyclonal antibodies to purified halibut SL were raised in rabbits, and a radioimmunoassay (RIA) was developed for measurement of plasma concentrations of SL using purified halibut SL as a standard. The RIA was tested in several flatfish species including Pacific halibut (Hippoglossus stenolepis), English sole (Pleuronectes vetulus), and rock sole (Lepidopsetta bilineata). The assay was specific for SL as indicated by absence of cross-reactivity with Atlantic halibut growth hormone, prolactin, and GTH alpha subunit. Dilutions of plasma and pituitary extracts from Pacific halibut, English sole, and rock sole were parallel to the Atlantic halibut SL standard curve, indicating that the assay is valid for a range of flatfish species. Using halibut SL antiserum, SL was localized in the pars intermedia of English sole pituitary, where it has been identified in previously examined teleost species. The RIA was used to measure plasma levels of SL in Atlantic halibut and English sole during reproductive development, and in English sole subjected to various types of environmental stressors, including handling and crowding. In both sole and halibut, plasma SL concentrations remained relatively constant throughout gonadal development, but dropped during or following ovulation. Plasma SL levels in English sole tended to increase in response to acute stress, in parallel with plasma cortisol levels.
Gen Comp Endocrinol 1997 Feb
PMID:Isolation, characterization, and radioimmunoassay of Atlantic halibut somatolactin and plasma levels during stress and reproduction in flatfish. 903 52

1. This work investigated the effects of androgens on the norepinephrine sensitivity of vasa deferentia from rats submitted to acute or repeated stress, as well as the participation of alpha1-adrenoceptors in the response of intact and bisected vasa deferentia from adult normal rats submitted to acute or repeated stress. 2. The acute stress produced subsensitivity to norepinephrine only in intact vasa deferentia from adult normal rats, which was prevented by lack of androgens, suggesting that the sensitivity may be dependent on the physiological level of androgen. 3. No change was observed in intact vas deferens sensitivity to norepinephrine in repeated stress, suggesting the occurrence of adaptation to elevated norepinephrine levels or a mild decrease in androgen levels or both. 4. The changes in sensitivity observed in acute and repeated stress may also be due to alterations in alpha1-adrenergic receptors that are located in the prostatic portion of the vas deferens.
Gen Pharmacol 1998 Mar
PMID:Noradrenergic response in vas deferens from rats submitted to acute and repeated stress. 951 96

Vasoactive intestinal peptide (VIP) is a potent releaser of prolactin (PRL) in domestic fowl, turkey, and ring doves. However, few comparative studies have investigated this in wild species. We tested the effects of intravenously administered chicken VIP on plasma PRL concentrations in four passerine species: the white-crowned sparrow (Zonotrichia leucophrys gambelii), the dark-eyed junco (Junco hyemalis), the Florida scrub-jay (Aphelocoma coerulescens), and the western scrub-jay (A. californica). In the white-crowned sparrow, junco, and Florida scrub-jay, which were tested during the breeding season, VIP induced a rapid increase in plasma PRL. Serial plasma samples taken after VIP injection in the white-crowned sparrow show a 10-fold increase in PRL within 2 min of treatment, followed by a gradual decline. Effects of VIP, as compared to saline, remained significant for at least 20 min after treatment. Western scrub-jays did not respond to intravenous VIP with a significant rise in PRL secretion, possibly because they were tested after termination of the breeding season. This study indicates that VIP control of PRL release may be widespread among avian species, and that seasonal changes in plasma PRL may be mediated in part at the level of the pituitary. In addition, analysis of the control data revealed no increase in plasma PRL as a result of injection or restraint, suggesting that unlike in mammals, PRL is not released during acute stress in passerines.
Gen Comp Endocrinol 1999 Mar
PMID:Effects of vasoactive intestinal peptide on plasma prolactin in passerines. 1006 94


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