Glucocorticoids bind with high affinity to intracellular receptors located in high density within discrete regions of the rodent and primate brain. The binding of [3H]corticosterone was compared in the brains of male vs female rats. The number and affinity of cytosol receptors in the hippocampus and hypothalamus were examined in vitro. The cytosolic binding capacity of the hippocampus is greater in the female than in the male. This difference in binding capacity is not dependent on the presence of gonadal steroids: the effect of gonadectomy was not significant for either sex. The difference is not due to transcortin since the binding capacity of [3H]dexamethasone is also greater in the female hippocampus. Receptor affinity in the female hippocampus is half that of the male value. In the hypothalamus, the dimorphism is in the opposite direction: the number of [3H]corticosterone cytosolic binding sites was found to be greater in the male. The male hypothalamus also showed a greater affinity for [3H]corticosterone than did the female. Ovariectomy increased the number of binding sites in the female hypothalamus. In vivo nuclear uptake of a tracer dose of [3H]corticosterone was determined in animals having intact gonads. The percent of tissue [3H]corticosterone present in cell nuclei from 4 brain regions, including the hippocampus and hypothalamus, was calculated per unit DNA. The concentrations of [3H]corticosterone in nuclei relative to tissue homogenates were higher in females than males for the 4 brain regions, but not for the pituitary or liver. The data are interpreted as suggesting that glucocorticoid secretion under basal conditions and during stress may differentially effect specific brain structures in male vs female rats.

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In this study, we evaluated the development of stress response in (1) two different species of quail, one species that is relatively fast-growing (Japanese quail, Coturnix japonica) and one that is relatively slow-growing (Gambel’s quail, Callipepla gambelii) and (2) two strains of a single species, the Japanese quail (wild-type and domesticated), that differ considerably in final size. Our data indicate that wild-type Japanese quail and Gambel’s quail have experienced trade-offs between growth and the stress response (e.g. Gambel’s quail have slower growth rates, but greater levels of CORT). However, the domesticated strain of Japanese quail used in this study seem to violate some predictions based on the life history theory (e.g. the domestic strain has faster growth rates and greater levels of CORT). The data in this study contribute to the understanding of differences in the stress response between species that exhibit different life history strategies.

<p dir="ltr">Juvenile stress (JS) is a known risk factor for the development of alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD), both of which frequently occur together, suggesting common genetic influences on vulnerability toward these disorders. The present study investigated the impact of JS on contextual fear learning and extinction, as well as corticosterone (CORT) responses before and after JS, before and after contextual fear conditioning (CFC), and after fear extinction in male and female high-alcohol-preferring (HAP2) and low-alcohol-preferring (LAP2) mice. We also measured unconditioned anxiety-related behavior in the light-dark-transition test. No line differences were seen in fear acquisition, however, HAP2 mice showed faster fear extinction compared to LAP2 mice. No effects of JS were seen in HAP2 mice, whereas in LAP2 mice, JS reduced fear acquisition in males and facilitated fear extinction in females. Females showed greater fear relative to males, regardless of subgroup. Anxiety-related behavior, assessed by the light-dark transition test, did not correspond with fear-related behavior, as LAP2 females demonstrated more anxiolytic-like responses than LAP2 males, while HAP2 males demonstrated more anxiolytic-like responses than LAP2 males. There were no line differences in CORT during the juvenile stage; however, adult LAP2 mice showed greater CORT levels than HAP2 mice at baseline and after CFC and extinction testing. These findings provide new information regarding fear learning and extinction in these unique mouse lines that model mechanisms theorized to contribute to co-morbid AUD and PTSD.</p>

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