Sex difference in adrenergic receptor-mediated glycogenolysis in rat livers.
Catecholamine-induced stimulation of hepatic glycogenolysis in male and female rats was studied by detecting the cytosolic free Ca2+ concentration ([Ca2+]i), cAMP generation and adrenergic receptor function. Increase in alpha 1-adrenergic receptor-mediated [Ca2+]i and beta-adrenergic receptor-mediated cAMP generation were examined using isolated hepatocytes. No difference was found in the alpha 1-adrenergic receptor-mediated response of [Ca2+]i in fura-2-loaded hepatocytes between males and females, while epinephrine-induced cAMP accumulation in hepatocytes was about 3-fold higher in females. The alpha 1- and beta-adrenergic receptor properties of the plasma membrane were evaluated by ligand binding studies using [3H]prazosin (alpha 1-adrenergic antagonist) and [125I]iodocyanopindolol (beta-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-gamma-S was also similar for both sexes. These results suggest that the sex difference of beta-adrenergic response is due to a difference in the guanine nucleotide regulatory binding proteins (G proteins) and/or beta-adrenergic receptor-Gs protein (the stimulatory G protein of adenylate cyclase) coupling ability.
Yagami
T
T
Shionogi Research Laboratories, Shionogi & Co., Ltd. Osaka, Japan.
Tohkin
M
M
Matsubara
T
T
D000262:Adenylyl Cyclases / Q000096:biosynthesis; D000322:Adrenergic Agonists / Q000494:pharmacology*; D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D004789:Enzyme Activation; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D016257:Fura-2 / Q000378:metabolism; D006019:Glycolysis; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008112:Liver Glycogen / Q000378:metabolism*; D008297:Male; D051381:Rats; D011941:Receptors, Adrenergic / Q000378:metabolism*; D012727:Sex Characteristics
D000322:Adrenergic Agonists; D008112:Liver Glycogen; D011941:Receptors, Adrenergic; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D016257:Fura-2; D004837:Epinephrine