Sulfated Polysaccharides From Gracilaria gracilis (Red Seaweed) Restores Testicular Glucose Metabolism by Improving FSH and Insulin Signaling in Rats With Type 2 Diabetes

Testicular glucose homeostasis plays important roles in testicular energy metabolism and male fertility, but it is altered in type 2 diabetes (T2D), leading to male infertility. In the present study, the therapeutic effect of sulfated polysaccharides (SPCs) from Gracilaria gracilis on testicular glucose metabolism was investigated in T2D rats. SPCs were administered to two groups of T2D rats at 150 and 300 mg/kg bodyweight, respectively. The T2D control group was administered water only, while metformin served as the control drug administered to the standard treatment group. Non-T2D rats served as the normal group. After 5 weeks of treatment, the rats were sacrificed and their testes harvested and analyzed for insulin, FSH, glucose, and glutathione metabolisms. Treatment with SPCs led to a significant increase in insulin, IRS-1, FSH, GLUT4, GSH, ATP levels, hexokinase, glucose 6-phisphate dehydrogenase, glyoxalase, glutathione reductase, and glutathione peroxidase activities, while improving testicular morphology. SPCs further led to significant depletion in glycogen phosphorylase, glucose 6-phosphatase, fructose-1,6-biphosphatase, aldose reductase, polyol dehydrogenase, ATPase, and ENTPDase activities. These results indicate the potentials of SPCs from G. gracilis to improve male fertility in T2D. This is evident by its ability to improve insulin-FSH signaling, glucose, energy metabolisms, and testicular morphology.