Effects of Obesity and Exercise Training on Testosterone Levels in Male Rats

Abstract

The purpose of this investigation was to study the effects of obesity and chronic exercise on sex organ testosterone levels in male rats. Lean and obese male Zucker rats were randomly assigned to a sedentary group and an exercise training group (lean sedentary: n=7, lean exercise: n=8, obese sedentary: n=7, obese exercise: n=7). The exercise group walked on a rat treadmill for 8 weeks. Testicular testosterone was extracted and total testosterone levels were measured by using radioimmunoassay. Compared to lean sedentary rats, obese sedentary rats had lower levels of testicular testosterone (concentration: 17.2±11.0 vs. 61.5±21.2 ng/g; total content: 50.8±29.4 vs. 191.5±80.3 ng; both P<0.001). There were no group differences between lean sedentary and lean exercise rats in testicular testosterone levels. However, compared to obese sedentary rats, obese exercise rats had higher testicular testosterone levels (concentration: 40.6±20.0 vs. 17.2±11.0 ng/g; total content: 119.6±52.4 vs. 50.8±29.4 ng, both P<0.05). These results support our previous findings that chronic exercise attenuated obesity‐related hypogonadism. Further studies are needed to clarify the underlying mechanisms.