Bromocriptine treatment increases lipolysis and steady-state levels of G proteins in adipocytes from lactating rats.
An increase in the rate of lipogenesis and a decrease in the lipolytic response to catecholamines can be observed in adipocytes after weaning or litter removal. Bromocriptine treatment of lactating rats also produces an increase in lipogenesis but fails to decrease the lipolytic response of adipocytes to catecholamines seen after weaning or litter removal. No changes in total number or affinity of beta-adrenergic receptors or adenosine A1 receptors were detected by bromocriptine treatment using radioligand binding assays. However, we observed an increase in the amount of radioactivity from [32P]NAD+ incorporated into alpha-Gs (192 +/- 26%) and alpha-Gi (178 +/- 33%) by cholera- and pertussis-toxin-catalyzed ADP-ribosylation, respectively, with the same treatment, Immunoblotting using RM/1 and AS/7 antisera, which specifically recognize alpha-Gs and alpha-Gi 1,2, respectively, confirmed the increase in the steady-state levels of these G-protein alpha-subunits. The increase in the steady-state levels of alpha-Gs may account, at least in part, for the increased lipolytic response of adipocytes to catecholamines in bromocriptine-treated rats.
Centro de Biología Molecular (UAM-CSIC), Universidad Autónoma Madrid, Spain.
F J
FJ
Moreno
G
G
Alonso
M
M
Ros
D000241:Adenosine / Q000378:metabolism; D000273:Adipose Tissue / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology*; D002395:Catecholamines / Q000494:pharmacology; D002478:Cells, Cultured; D005260:Female; D019204:GTP-Binding Proteins / Q000032:analysis* / Q000737:chemistry; D007774:Lactation; D008066:Lipolysis / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
D002395:Catecholamines; D001971:Bromocriptine; D019204:GTP-Binding Proteins; D000241:Adenosine