Glucocorticoids decrease serum adiponectin level and WAT adiponectin mRNA expression in rats

Accumulating evidence suggests that adiponectin plays an important role in the genesis of obesity and insulin resistance. Although it has been shown that glucocortocoids (GC) inhibit adiponectin expression in vitro, there exist discrepant results in vivo. In this study, we observe the effect of GC on the serum adiponectin level and adiponectin expression in white adipose tissue (WAT) in male SD rats. An obese rat model was made by a high-fat diet. Both non-obese and obese rats were randomly divided into normal saline (intraperitoneal injection with normal saline 0.2 ml/100 g day for 20 days, NS), a low dose GC group (intraperitoneal injection with hydrocortisone sodium succinate 5 mg/kg day for 20 days, LDG) and a high dose GC group, respectively (intraperitoneal injection with hydrocortisone sodium succinate 15 mg/kg day for 20 days, HDG). Serum adiponectin levels were detected by ELISA and the adiponectin mRNA level was assayed by Northern blot. The serum adiponectin level significantly decreased after 80 days of the high-fat diet ( P < 0.05), while it was not decreased after 80 days of the chow diet ( P > 0.05). The serum adioponectin levels in both the non-obese and obese rats were significantly decreased after a 20-day GC injection period ( P < 0.01). The adiponectin mRNA levels in epididymal fat after high dose GC injection, in both non-obese and obese rats were also decreased ( P < 0.001). A high-fat diet decreased serum adiponectin levels in the rat. GC decreased serum adiponectin levels, and this might be due to inhibited adiponectin mRNA expression in WAT. High-fat diet and GC have a synergistic effect on inhibiting adiponectin expression in rats.