The hypothalamus-pituitary-adrenal (HPA) axis is activated during an immune challenge to liberate energy and modulate immune responses via feedback and regulatory mechanisms. Inflammatory cytokines and prostaglandins are known contributors to HPA activation; however, most previous studies only looked at specific time points following LPS administration. Since whole bacteria have different immun...

Studies of intravenous self-administration and psychomotor effects of drugs have recently suggested that stress-induced corticosterone secretion may be an important factor determining vulnerability to drugs of abuse. In this report, we studied if basal physiological corticosterone secretion modulates sensitivity to cocaine and morphine, and if changes in the reactivity of mesolimbic dopaminergi...

Corticosterone and insulin play complex roles in the amount and composition of calories ingested, and the utilization and deposition of this energy. Understanding the interplay of these two hormones is complicated because increasing concentrations of corticosterone dose-dependently increase circulating insulin levels. We addressed individual contributions of each hormone by controlling, at stea...

Calorie restriction of young male rats increases plasma prolactin, decreases luteinizing hormone (LH) and testosterone, and disrupts their 24 h secretory pattern. To study whether this could be the consequence of stress, we examined the 24 h variations of plasma adrenocorticotropic hormone (ACTH) corticosterone, growth hormone (GH), leptin, and adrenal corticosterone. Rats were submitted to a c...

Acute low doses of ethanol can produce reversible memory deficits, but it is unknown whether they persist upon chronic use. We investigated whether the chronic intake of a low dose of ethanol induces memory impairments in the ethanol-preferring C57BL/6J mouse strain. Because stress precipitates alcohol abuse and the stress hormone corticosterone contributes to memory processes, ethanol consumpt...

These studies further evaluated the relative role of mineralocorticoid (type I) and glucocorticoid (type II) receptors in mediating corticosteroid feedback regulation of the hypothalamic-pituitary-adrenal (HPA) axis. Acute treatment of rats with the selective mineralocorticoid receptor antagonist, RU28318 (50 mg/kg sc), produced elevated basal corticosterone levels in the morning, but had no ef...

All reptiles studied to date show an increase in circulating corticosterone following capture. This rise in corticosterone has also been shown in a number of instances to result in a decline in reproductive steroids within hours after capture. As a result of these observations it has been considered imperative to collect blood samples as soon as possible after capture to get reliable measures o...

Increased secretion of adrenal cortical steroids may account in part for its cancer inhibitory activity of energy restriction (ER). To test this hypothesis, a study was conducted to determine the effects of dietary administration of corticosterone on the post-initiation stage of mammary carcinogenesis. Eighty-four female Sprague-Dawley rats were injected with 50 mg 1-methyl-1-nitrosourea/kg bod...

Although plasma corticosterone is considered the main glucocorticoid involved in regulation of stress responses in rodents, the presence of plasma cortisol and whether its level can be used as an indicator for rodent activation of stress remain to be determined. In this study, effects of estrous cycle stage, circadian rhythm, and acute and chronic (repeated or unpredictable) stressors of variou...

The effects of acute environmental stressors on reproduction in wildlife are often difficult to measure because of the labour and disturbance involved in collecting accurate reproductive data. Stress hormones represent a promising option for assessing the effects of environmental perturbations on altricial young; however, it is necessary first to establish how stress levels are affected by envi...