Regulation of white adipocyte guanine nucleotide binding proteins Gsα and [formula omitted] by testosterone in vivo : Influence of regional fat distribution

Abstract

The influence of the androgenic status on the steady-state amounts of Giα 1–2 and Gsα subunits was compared in hamster fat cell membranes from the femoral subcutaneous (FSC) and epididymal (EP) adipose tissues, using immunoblotting experiments. In sham-operated hamsters, Giα 1–2 and Gsα steady-state amounts found in FSC fat cells were 38% and 40% reduced, respectively, as compared to EP adipocytes. In EP fat cells, castration induced a down-regulation of both Giα 1–2 (−39%) and Gsα (−33%), whereas testosterone replacement restored Gsα, but not Giα 1–2 levels, to control values. In contrast, these G protein α-subunits were insensitive to the androgenic status in FSC fat cells. These data provide the first evidence that the androgenic status can modulate the expression of both the Giα 1–2 and Gsα subunits of the fat cell adenylate cyclase regulatory Gi and Gs proteins and that this modulation depends on the anatomical origin of these cells.