AJP - Regulatory, Integrative and Comparative Physiology, Vol 273, Issue 1 153-R160, Copyright © 1997 by American Physiological Society
Change from beta- to alpha-adrenergic glycogenolysis induced by corticosteroids in female rat liver
M. Moriyama, Y. Nakanishi, S. Tsuyama, Y. Kannan, M. Ohta and T. Sugano
Department of Veterinary Physiology, College of Agriculture, Osaka Prefecture University, Japan.
The conversion of beta- to alpha-adrenergic glycogenolysis by
corticosteroids was studied in perfused livers of mature female rats.
Isoproterenol stimulated glucose production more effectively in female rats
than in male rats, but the difference in its stimulatory effect disappeared
in adrenalectomized (ADX) rats, whereas it remained in adrenodemedulated
rats. When ADX female rats were treated with dexamethasone sulfate,
alpha-responses increased and beta-responses decreased, depending on the
concentration of dexamethasone sulfate. The treatment of female rats with
1.5 mg/kg dexamethasone sulfate changed the levels of the alpha- and
beta-responses to those observed in male rats, and the changes were
associated with changes in the number of receptors. Although periodicity of
changes in plasma corticosterone levels was observed in both male and
female rats, the extent of circadian variations was significantly lower in
female rats during the estrous cycle than in male rats. The variations in
plasma corticosterone levels and in both alpha- and beta-responses after
ovariectomy approached those in male rats. The results suggest that the
level of plasma corticosterone might play an important role in the
regulation of the relative levels of alpha- and beta-adrenergic responses
in female rats.
