Abstract
Hippocampal volumes previously determined in monkeys by magnetic resonance imaging are used to test the hypothesis that small hippocampi predict increased stress levels of adrenocorticotropic hormone (ACTH). Plasma ACTH levels were measured after restraint stress in 19 male monkeys pretreated with saline or hydrocortisone. Monkeys were then randomized to an undisturbed control condition or intermittent social separations followed by new pair formations. After 17 months of exposure to the intermittent social manipulations, restraint stress tests were repeated to determine test/retest correlations. Individual differences in postrestraint stress ACTH levels over the 17-month test/retest interval were remarkably consistent for the saline (r(s) = .82, p = .0004) and hydrocortisone (r(s) = .78, p = .001) pretreatments. Social manipulations did not affect postrestraint stress ACTH levels, but monkeys with smaller hippocampal volumes responded to restraint after saline pretreatment with greater increases in ACTH levels with total brain volume variation controlled as a statistical covariate (beta = -.58, p = .031). Monkeys with smaller hippocampal volumes also responded with diminished sensitivity to glucocorticoid feedback determined by greater postrestraint ACTH levels after pretreatment with hydrocortisone (beta = -.68, p = .010). These findings support clinical reports that small hippocampi may be a risk factor for impaired regulation of the hypothalamic-pituitary-adrenal axis in humans with stress-related psychiatric disorders.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.