Angiotensin II receptor blockers downsize adipocytes in spontaneously type 2 diabetic rats with visceral fat obesity

To investigate the influence of blockade of the renin-angiotensin system (RAS) on adipocytes, we compared the effect of telmisartan versus valsartan and amlodipine on adipocyte cellularity in the spontaneously type 2 diabetic, obese rat model.

Male Otsuka Long Evans Tokushima Fatty rats, 8-week-old, were divided into four groups as follows: valsartan (V) group (10 mg/kg, n = 12), telmisartan (T) group (5 mg/kg, n = 12), amlodipine (A) group (2 mg/kg, n = 12), and control (C) group (n = 12). Each drug was mixed with chow and given for 16 weeks.

Although no significant differences were observed in the fasting plasma glucose level between the groups, the fasting plasma insulin level for group T was significantly lower than that for group C. Histopathologic examination showed that the ratio of small adipocytes in groups V and T was significantly higher than that in group C, with the ratio of large adipocytes and the mean adipocyte size shown to be significantly lower in groups V and T than in group C. Furthermore, group T was shown to have a significantly higher ratio of small adipocytes, a significantly lower ratio of large adipocytes, as well as a significantly lower mean adipocyte size, compared to group V.

Although both valsartan and telmisartan downsized adipocytes, adipocyte downsizing was significantly greater with telmisartan compared to valsartan. The likely mechanism for this difference was thought to be the PPAR-gamma-mediated action of telmisartan.