Compensatory adrenal growth in relation to stress of surgery and estradiol in adult male rats.

ACTH infusion at the time of unilateral adrenalectomy inhibits the early rapid compensatory growth (CAG) in the remaining adrenal. We examined the hypothesis that different duration of surgery and/or the enhanced response to the stress of surgery, induced by estradiol treatment, might modify CAG. Adult male rats untreated, estradiol benzoate treated (EB) 300 microg/kg or vehicle treated (VE) for 3 days, were Sham or left adrenalectomized after 18 to 20 min procedure (prolonged surgery) or after 14 to 16 min procedure (short surgery).

Inverse relationship of hippocampal serotonin to avoidance behavior, serotonergic activation by emotional stress differentiated by estrous cycle and surgical stress.

The hippocampus is involved in learning, affect, and the neurobiology of stress. After recording individual emotional reactivity (ER) during handling for vaginal smear screening (VSS), serotonin (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA), in the hypothalamus-preoptic area (HY-PA) and hippocampus were studied in two rat lines with different susceptibility to Freund's adjuvant arthritis (FAA), in relation to active avoidance behavior (AB), and under basal conditions in the FAA susceptible strain, in relation to ER, cycle stage and 20 h prior surgical stress. FAA susceptible rats compared to non-susceptible under equally low ER, showed higher AB, but lower 5-HIAA and 5-HIAA/5-HT ratio, under basal conditions, and upon termination of avoidance assay, only in hippocampus.