Rosiglitazone modulates insulin-induced plasma membrane area changes in single 3T3-L1 adipocytes

Abstract

In this study we hypothesized that rosiglitazone, an antidiabetic high-affinity agonist for the peroxisome proliferator-activated receptor gamma, affects the plasma membrane (PM) turnover in single 3T3-L1 adipocytes. To study the PM turnover, the patch-clamp electrophysiological method was used to measure changes in membrane capacitance (C-m), a parameter linearly related to the PM area. Microscopy results show that the presence of rosiglitazone in the differentiating medium significantly increased the differentiation of 3T3-L1 adipocytes in cell culture, based on oil red O-stained area (11.4 +/- 1.2%) vs. controls (3.1 +/- 0.5%). Moreover, rosiglitazone treatment significantly reduced the size of single 3T3-L1 adipocytes; their average radius of 21.1 +/- 1.1 mu m in controls was reduced to 17.5 +/- 0.5 mu m in rosiglitazone-treated cells. Consistent with this, insulin application increased the rate of C-m increase to 2.34 +/- 0.10%/min, which was significantly different from controls (0.12 +/- 0.08%/min). However, pretreatment of cells with rosiglitazone prior to the treatment with insulin resulted in an attenuated rate of C (m) increase. These data support the involvement of insulin in the modulation of membrane area and show that treatment by rosiglitazone reduced the insulin-mediated membrane area increase in 3T3-L1 adipocytes.