ADRENALECTOMY AFTER WEANING RESTORES BETA(3)-ADRENERGIC RECEPTOR EXPRESSION IN WHITE ADIPOCYTES FROM C57BL 6J-OB/OB MICE/

The role of hypercorticism in the development of compromised beta-adre nergic signaling in adipose tissue was assessed in ob/ob mice adrenale ctomized at 4 weeks of age and studied 1 and 3 weeks thereafter. Adren alectomy prevented the rapid increase in body weight and fat depositio n between 4 and 5 weeks of age in ob/ob mice and produced a phenotype indistinguishable from that of lean mice. However, adrenalectomized ob lob mice became intermediate between lean and ob lob mice by 7 weeks of age. Adipocyte beta(3)-adrenergic receptor (AR) messenger RNA level s were similar between lean and adrenalectomized ob/ob mice at both ti me points and were 4- to 8-fold higher than messenger RNA levels in ob /ob mice. As judged by maximal activation of adenylyl cyclase by a bet a(3)-AR-selective agonist, adrenalectomy also restored functional acti vity of the beta(3)-AR to levels above or equivalent to those seen in lean mice at both time points. The present results suggest that develo pment of hypercorticism at or before weaning in ob lob mice represses expression of the beta(3)-AR and prevents the normal postweaning devel opment of this signaling system in the adipocyte.