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). The response to surgical stress was evaluated by comparison of the left adrenals between Sham and left adrenalectomized animals matched for treatment, surgery and body weight. Autopsy was done 88-90 h after surgery. The right adrenals following prolonged surgery for unilateral adrenalectomy after EB or VE treatment were examined histologically. The number of rats with enlarged zona glomerulosa was greater (p<0.01) in EB than in VE-treated rats. Prolonged surgery induced significant stress response in untreated and EB-treated rats in parallel with attenuation of CAG. Stress response of lower magnitude in VE (22%) than in EB-treated rats (61.4%) was followed by significant CAG. After short duration surgery, significant CAG, with an absence of stress response, was apparent in VE and EB rats. The extent of CAG was found inversely related to initial adrenal size. In conclusion, these results suggest that prolonged surgical stress, increased response to this stress and enlarged glomerulosa are negatively related to CAG, possibly through CAG suppression by increased ACTH and/or adrenocortical secretion.