Compensatory Increase in Adrenal Weight and Dopamine-β-hydroxylase Activity after Unilateral Adrenalectomy

Abstract

Abstract

Changes in adrenal weight and adrenomedullary dopamine-β-hydroxylase (DBH) activity following either unilateral adrenalectomy and pinealectomy separately or both operations combined were examined in adult male rats. Animals were acclimated in continuously darkened animal quarters from 10 days prior to surgery to sacrifice 10 days postoperatively. Adrenal DBH activity was measured by a coupled radioenzymatic method. Compensatory adrenal hypertrophy following unilateral adrenalectomy was associated with a significant increase in adrenal DBH activity. However, when unilateral adrenalectomy was combined with pinealectomy, this change in DBH activity no longer occurred. Pinealectomy alone did not bring about any alteration in adrenal DBH activity. Absolute and relative adrenal wet weights were significantly increased after unilateral adrenalectomy, either with or without pinealectomy. These results suggest that, at least in darkness, the pineal contributes to the mechanism whereby compensatory increase in adrenal DBH activity occurs, but not in that involving increase in adrenal weight.