Effects of exercise on concentration of serum leptin in diabetic rats

Objective To study if exercise can affect serum leptin level that related with body weight regulation and observe the influence of different exercise intensity on body weight, blood glucose, serum insulin and leptin in streptozotocin(STZ) diabetic rats. Methods Six experimental groups of rats were investigated: normal controls (NC ), normal exercise (NE ), diabetic group (DG), low-intensity exercise diabetie group (LEG), medium-intensity and great-intensity exercise group (MEG and GEG. Swimming is trained according to Plog metheds. Results After 8-week swimming, serum leptin concentration of NE markedly decreased. Before swimming, body weight, serum insulin and leptin level of all the STZ diabetic rats were significantly lower than that of NC, and blood glucose were higher. Eight weeks later, only the rals of MEG increased obviously in body weight weekly, and concentration of blood glucose decreased 35%, serum insulin level increased 38%, serum leptin level increased 40% respectively compared with that before excercise. However, 8 weeks later the above indexes in LEG and GEG showed no significant differences with those of pre-exercise. Multiple relation and stepwise regression;anatysis were applied, indicating that in diabetic rats only serum insulin was a significant influencing factor of serum leptin. Conclusions Under normal physiological condition decreased serum leptin leve1 by exercise is an adaptive reaction to maintain stable body weight and to balance energy, while under STZ diabetic condition, leptin seems to be closely related with insulin. Middle-intensity exercises reduce blood glucose and improve insulin sensitivity, at the same time it seems to have improved leptin sensitivity. Insufficient exercises or excessive exercises have no obvious therapeutic effect on diabetes.