Aerobic training and vitamin D supplementation effects on diabetes-related parameters in a rat model of type 2 diabetes.

Background: Diabetes mellitus (DM) is characterized by disturbances in glucose, lipid, and energy metabolism, including dyslipidemia and dysregulation of metabolic peptides like spexin; however, the effects of combined interventions, such as aerobic training and nutritional intervention, on these parameters are not fully elucidated. The objective of this study was to investigate the influences of aerobic training (AT) and vitamin D (Vit D) supplementation on the lipid profile and spexin levels in a model of rats with type 2 diabetes (T2D).

Methods: A total of 56 male Wistar rats were divided into two groups: SHAM (non-diabetic control; n = 8) and diabetic (n = 48). The diabetic rats were further divided into six groups: AT with high doses of vitamin D (D + AT + HD; 10,000 IU/kg/week), AT with moderate doses of vitamin D (D + AT + MD; 5,000 IU/kg/week), high doses of vitamin D (D + HD; 10,000 IU/kg/week), moderate doses of vitamin D (D + MD; 5,000 IU/kg/week), AT receiving vehicle (sesame oil; D + AT + oil), and control (oil-receiving; D + C). To induce type 2 diabetes, rats were first fed a high-fat diet (HFD) for 2 weeks to induce obesity, followed by an intraperitoneal injection of 110 mg/kg nicotinamide and 55 mg/kg streptozotocin (STZ) dissolved in 0.1 M citrate buffer (pH 4.5). Blood samples were collected 48 h after the last training session under anesthesia for measuring spexin levels, and lipid profile parameters. Statistical analyses were performed using the paired t-test, one-way analysis of variance (ANOVA), and Tukey post hoc test.

Results: Compared to the SHAM rats, there were significant increases in body weight, BMI, FI, and WC in the diabetic rats (p < 0.001). Also, there was a significant decrease in body weight, BMI, FI, and WC of the diabetic groups who received interventions, especially in D + AT + HD (body weight: -11.07%, BMI: -10.25%, FI: -19.16%, WC: -16.54%). The lipid profiles were significantly improved, with the lowest total cholesterol (TC), triglycerides (TG), and low-density lipoprotein (LDL) levels and the highest high-density lipoprotein (HDL) levels being found in the D + AT + HD group compared with the D + C group (p < 0.05). Moreover, the D + AT + HD group had elevated spexin levels compared with the other diabetic groups, which may play a metabolic role.

Conclusion: AT and Vit D supplementation effectively normalized serum lipids and increased spexin levels in T2D rats. These findings suggest that AT and Vit D supplementation may serve as potential therapeutic strategies for managing T2D and its associated complications. Further studies are needed to elucidate the underlying mechanisms and to evaluate the long-term effects of these interventions in humans.