Figure 7.

Rosiglitazone-induced multilocularization of adipocytes is related to the expression of PCG-1α and perilipin. The indicated adipose tissues (SF, subcutaneous fat; EF, epididymal fat; RF, retroperitoneal fat) were harvested from C57BL/6J mice that had treated with nothing (Control or C) or rosiglitazone (~15 mg/kg/day; R) for 3 weeks. (A) Subcutaneous adipose tissues were whole-mounted, co-immunostained for PGC-1α (green), DAPI (white), perilipin (red), and collagen IV (blue), and merged. Note that rosiglitazone markedly induces PGC-1α expression in the nuclei of multilocular adipocytes (yellow arrowheads). Results were similar from 3 independent experiments. (B) Tissue lysates from the isolated adipocytes were separated by SDS-PAGE and immunoblotted with anti-perilipin antibody (upper panel). Each protein lysate was also immunoblotted with anti-β-actin antibody to quantify the amount of total protein loaded (lower panel). (C) The relative ratio measured for each control is arbitrarily presented as 1. Bars represent the mean ± SD from 3 experiments. ^*P < 0.05 versus each C. Scale bars, 20 µm. (D) Schematic diagram of a proposed model for the changes in adipocytes of adult WAT induced by PPARγ activation. The processes depicted are: multilocularization with increased expression of perilipins, an increased number of smaller adipocytes, which are the result of the reduced size of differentiated adipocytes (a) and adipogenesis of resident preadipocytes (b), and increased mitochondrial content with increased expression of perilipin. These changes provide favorable conditions for the mobilization of lipids from adipocytes into circulation and vice versa with enhanced lipolytic and lipogenic activities.