Sex Difference in Adrenergic Receptor-Mediated Glycogenolysis in Rat Livers

概要

論文の詳細を見る
Catecholamine-induced stimulation of hepatic glycogenolysis in male and female rats was studied by detecting the cytosolic free Ca2+ concentration ( [Ca2+]1), cAMP generation and adrenergic receptor function. Increase in α1-adrenergic receptor-mediated [Ca2+]1 and β-adrenergic receptor-mediated cAMP generation were examined using isolated hepatocytes. No difference was found in the α1-adrenergic receptor-mediated response of [Ca2+]1 in fura-2-loaded hepatocytes between males and females, while epinephrine-induced cAMP accumulation in hepatocytes was about 3-fold higher in females. The α1 and β-adrenergic receptor properties of the plasma membrane were evaluated by ligand binding studies using[3H]prazosin (α1-adrenergic antagonist) and [125I] iodocyanopindolol (β-adrenergic antagonist); and little sex difference was found in either affinity or the number of binding sites of[3H]prazosin and [125I] iodocyanopindolol. Activation of adenylate cyclase by forskolin and GTP-γ-S was also similar for both sexes. These results suggest that the sex difference of β-adrenergic response is due to a difference in the guanine nucleotide regulatory binding proteins (G proteins) and/or β-adrenergic receptor-Gs protein (the stimulatory G protein of adenylate cyclase) coupling ability.