Antiobesity effects of Isaria sinclairii by repeated oral treatment in obese Zucker rats over a 4-month period

In the present study, the antiobesity effects of Isaria sinclairii (I. sinclairii, a fungus cultured on silkworms) powder were investigated in obese (fa/fa) Zucker rats over 4 mo. Rats were given 5 or 10% (w/w) I. sinclairii powder (I. S.), 10% mulberry leaf powder, or 10% silkworm powder mixed with standard diet; a fifth (control) group was given standard diet alone. Dose-dependent decreases in rate of body weight gain were observed in the IS-treated groups after 2 wk of treatment. Interestingly, weights of abdominal adipose tissues surrounding the epididymides were markedly reduced by I. S., in parallel with an attenuated body weight gain. However, no significant differences were observed versus the control group in terms of urinalysis or ocular or histopathological examinations. In the serum, total cholesterol, triglyceride, bilirubin, and low-density lipoprotein (LDL) were significantly lower in the 10% I. S. group than control after 17 wk of treatment. The mulberry leaf diet (10%) significantly reduced serum bilirubin levels. Obese (fa/fa) Zucker rats displayed markedly elevated serum leptin levels (>24.6%) in the I. S. 5 and 10% groups compared with nontreated controls. Data suggest that I. sinclairii exerts an antiobesity effect in Zucker obese rats.