We tested the hypothesis that parental effort modulates the magnitude of corticosterone and prolactin responses to stress in a long-lived bird, the Black-legged kittiwake (Rissa tridactyla). To do so, we compared corticosterone and prolactin responses to capture/restraint stress between chick-rearing birds and failed breeders (no parental effort). We predicted that (1) the increase in plasma co...

Plasma ACTH concentrations in 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD)-treated rats (50 micrograms/kg; single, oral dose) were 2.1-, 2.1-, 2.9-, 1.7-, 1.5-, 2.0- and 3.0-fold greater than control values, respectively, at days 1, 3, 5, 7, 10, and 14. At days 1 and 5 plasma corticosterone concentrations were increased 5.1- and 8.0-fold, respectively; whereas, at days 10 and 14 they were depr...

Seizures, including electrically induced seizures (ECS), activate the hypothalamo-pituitary-adrenal (HPA) axis in rats. The present studies were undertaken to characterize the effects of repeated ECS on hormone release and brain adrenal steroid receptors. Repeated ECS led to an increase in adrenal weight, an increase in the corticosterone response to the eighth seizure compared to the first sei...

In vertebrates, baseline glucocorticoid concentrations vary predictably on a diel basis, usually peaking shortly before the onset of activity. Presumably, circadian patterns in glucocorticoid secretion have evolved to match predictable rises in energetic need. In mice from lines selectively bred for high voluntary wheel-running, previous studies have reported that baseline plasma corticosterone...

–The present study investigated the effects of 21 days of chronic restraint stress on neural and endocrine parameters in male and female rats. Consistent with previous results, repeated restraint stress induced apical dendritic atrophy (a decrease in the number of apical branch points and dendritic length) of the CA3c pyramidal neurons in male rats. In contrast, female rats did not show signifi...

Augmented cardiovascular responses to acute stress can predict cardiovascular disease in humans. Chronic systemic increases in glucocorticoids produce enhanced cardiovascular responses to psychological stress; however, the site of action is unknown. Recent evidence indicates that glucocorticoids can act within the dorsal hindbrain to modulate cardiovascular function. Therefore, we tested the hy...

This study investigates the relationships between plasma corticosterone concentrations and white cell counts in captive females of the viviparous lizard Egernia whitii during two phases of the reproductive cycle. Gestating and postpartum females were captured in the field and held in the laboratory for 4 weeks. Plasma corticosterone and progesterone concentrations and white blood cell counts we...

In 19 control subjects, 33 patients with essential hypertension and normal plasma renin activity (PRA) and 11 patients with low PRA, secretory rates of 18-hydroxy-11-deoxy-corticosterone (18-OH DOC), 11-deoxycorticosterone (DOC) and corticosterone were measured. Patients with low PRA were significantly older and had higher arterial pressure and slightly lower plasma potassium levels than patien...

The purpose of this study was to determine the effect of chronic blockade of the brain renin-angiotensin system on the hormonal response to stress in spontaneously hypertensive rats (SHR). To this end, we measured changes in plasma corticosterone, vasopressin, plasma renin activity, aldosterone, norepinephrine, and epinephrine in SHR treated with a 4-week intracerebroventricular infusion of cap...

Basal plasma levels of corticosterone increased gradually during the second half of incubation, reaching a peak around the time of hatching. Stress resulted in a very significant elevation of corticosterone above the basal level in embryos 16 days or older, but not in younger embryos. Newly hatched chicks did not respond to stress, but a typical stress response was evident one week after hatchi...