Abstract: ACKGROUND: Type 2 diabetes mellitus is often accompanied by renal inflammation and cellular apoptosis, contributing to diabetic nephropathy. However, the mechanistic interplay of combined swimming exercise and probiotic intervention in this context remains to be fully elucidated.
OBJECTIVE: To investigate the effects of swimming exercise and probiotics on renal function level, renal tissue apoptosis and inflammatory factors in type 2 diabetic rats.
METHODS: There were 60 SPF grade male Sprague-Dawley rats at 8 weeks of age. Ten rats were randomly selected as the normal group, and 50 rats in the modeling group were injected intraperitoneally with streptozotocin to establish a rat model of type 2 diabetes mellitus. Forty rats successfully molded were selected and randomly divided into the diabetic group, the swimming exercise group, the probiotic group, the swimming exercise + probiotics group (combined intervention group), with 10 animals in each group. The rats in the swimming exercise and combined intervention groups were subjected to weightless swimming exercise once a day for 6 days per week, with swimming times of 15, 25 and 40 minutes in the first 3 days of the first week, and 60 minutes per day starting from the 4th day, for a total of 6 weeks of training. The rats in the probiotic and combined intervention groups were gavaged with a solution of 10.0 mL/kg/d PiLeJe probiotic bacteria (at a concentration of 107 CFU/mL) for 1 hour prior to the training. Kidney function indexes, apoptotic gene expression, inflammatory factor indexes and protein expression were measured.
RESULTS AND CONCLUSION: (1) The fasting blood glucose levels of rats in the combined intervention group were lower than those in the diabetic group (P < 0.01). The urinary microalbumin levels of rats in the swimming exercise group, probiotic group, and combined intervention group were all lower than those in the diabetic group (P < 0.01). The serum urea nitrogen levels of rats in the swimming exercise group and combined intervention group were both lower than those in the diabetic group (P < 0.01). The serum creatinine and cystatin C levels of rats in the combined intervention group were both lower than those in the diabetic group (P < 0.01). (2) The levels of tumor necrosis factor α, interleukin 6, interleukin 1β, nuclear factor κB inhibitory protein α, and ultrasensitive C-reactive protein were lower in the swimming exercise, probiotic, and combined intervention groups than in the diabetic group (P < 0.05 or P < 0.01). In addition, the level of interleukin 6 was lower in the combined intervention group than the diabetic, swimming exercise and probiotic groups (P < 0.01). (3) The expression of Bax, Caspase-3 and P53 was lower in the swimming exercise, probiotic and combined intervention groups than the diabetic group (P < 0.05 or P < 0.01). The expression of Bcl-2 was higher in the swimming exercise, probiotic and combined intervention groups than the diabetic group (P < 0.05 or P < 0.01). (4) The protein expression of nuclear transcription factor κB was lower in the probiotic and combined intervention groups than in the diabetic group (P < 0.05). Toll-like receptor 4 protein expression was lower in the combined intervention group than in the diabetic group (P < 0.05). The protein expression of interleukin 17 was lower in the probiotic and combined intervention groups than in the diabetic group (P < 0.05 or P < 0.01). To conclude, swimming exercise and probiotic intervention could reduce blood glucose, improve renal function indexes and inhibit renal inflammatory response, so as to achieve the protection of renal function. The protective effect of the combined intervention may be related to the involvement of inflammatory factors nuclear transcription factor κB, Toll-like receptor 4 and interleukin 17 in the regulation of cellular inflammation and inhibition of apoptotic factors Bax, Bcl-2, Caspase-3 and P53. And the effect of swimming exercise combined with probiotic intervention is superior to that of swimming exercise or probiotics alone.

Key words: swimming exercise, probiotics, type 2 diabetes mellitus, kidney tissue, inflammatory factors, apoptotic genes