Exercise training and de-training effects on serum leptin and TNF-α in high fat induced diabetic rats.

Background: Adipocytokines, which are secreted by the adipose tissue, contribute to the pathogenesis of obesity-related complications. To evaluate this assumption, we investigated the effects of aerobic exercise training (AET), resistance exercise training (RET), and 4 weeks of de-training on serum leptin and TNF-α levels in diabetic rats.

Method: 36 Wistar rats were divided into normal diet (ND) (control, RET, AET) and high-fat diet (HFD) + STZ (control, RET, AET) groups. Serum insulin, leptin, and TNF-α levels were assessed by commercial ELISA kits. Also fasting blood glucose (FBG), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG) levels were measured by the colorimetric kits.

Results: Diabetes induction increased body weight (BW) and FBG, and decreased insulin compared to the ND rats' groups (p < 0.001). 12-weeks of AET and RET programs in the trained diabetic rats led to a decrease in TG, LDL-C, leptin, TNF-α, and FBG, and an increase in insulin compared to the HFD + STZ-C group (p < 0.001). Besides, there was no difference between AET and RET in improving the variables studied (p > 0.05). Also, de-training led to increased BW, TG, leptin, and TNF-α compared to the end of the exercise training (p < 0.05). The correlation between the variables studied was established at different stages of the study (p < 0.05), and only BW was not correlated with insulin during exercise training and de-training (p > 0.05).

Conclusion: These findings indicate that both AET and RET are useful in reducing levels of serum adipocytokines (TNF-α, leptin) in diabetic and non-diabetic rats. At the same time, 4 weeks of de-training was sufficient to lose the metabolic adaptations.