Abstract
Adipocytes are known to release adipokines which are related with the pathogenesis of metabolic and cardiovascular complications of obesity. The expressions and releases of adipokines are shown to depend on adipocyte size. In order to prevent obesity-related metabolic and cardiovascular complications, therefore, it will be important to reduce adipocyte size in obese individuals. To this end, exercise training (ET) is used to reduce adipocyte size. However, the effect of ET on relationship between fat cell size and the adipokines expressions remains unknown. In the present study, we tried to clarify this issue. The rats (Male Wistar, SLC, Japan) in the ET group were subjected to exercise on a treadmill5 days/week for 9 weeks. The sedentary control animals (C) were not subjected to running. Adipocytes were isolated from the epididymal adipose tissue. The adipocytes were filtered through some meshes of which each pore size is different, and then the different size of adipocytes was collected. Total RNA was prepared and mRNA expressions were determined by quantitative RT-PCR. All experiments were approved by the Animal Care Committee of our institute. The adipose tissue mass and adipocyte size were significantly less in ET than in C. Either leptin or adiponectin mRNA expression was well correlated with adipocyte size in both groups. Thus, mRNA expressions of both adipokines would depend on adipocyte size. Consequently, it is possible that ET reduces adipocyte size, thereby resulting in size-dependent changes in leptin and adiponectin mRNA expressions. [J Physiol Sci. 2008;58 Suppl:S161]
