Effects of oestrogen on adenylate cyclase system and glucose output in rat liver.
Effects of chronic oestrogen treatment on catecholamine- and glucagon-sensitive adenylate cyclase activity and glucose output in hepatocytes of castrated male rats were studied. In hepatocytes from male intact or castrated rats, the beta-adrenergic agonist isoprenaline did not stimulate adenylate cyclase activity and glycogenolysis, but glucagon markedly stimulated all these activities. Treatment of castrated animals with 17 beta-oestradiol for 7 days led to the appearance of beta-adrenergic-stimulated increases in both cyclic AMP generation and glucose output. The basal, glucagon- or fluoride-stimulated activities of adenylate cyclase of hepatic membranes prepared from oestrogen-treated rats were similar to those of control animals. Treatment with oestrogen did not influence the number or affinity of beta-adrenergic receptors. In hepatic plasma membranes from control rats, GTP failed to decrease the affinity of beta-adrenergic receptors for agonists, whereas the GTP-induced shift was apparently observed in those from oestrogen-treated animals. These results suggest that oestrogen is able to facilitate the coupling of hepatic beta-adrenergic receptors to the enzyme by increasing the effectiveness of receptor-guanine nucleotide regulation.
Shima
S
S
Department of Biochemistry, St. Marianna University School of Medicine, Kanagawa, Japan.
Okeyama
N
N
Akamatu
N
N
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D004967:Estrogens / Q000494:pharmacology*; D005947:Glucose / Q000096:biosynthesis*; D007545:Isoproterenol / Q000494:pharmacology; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism
D004967:Estrogens; D011943:Receptors, Adrenergic, beta; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D005947:Glucose; D007545:Isoproterenol