Dendrobium nobile-derived polysaccharides ameliorate spermatogenic disorders in mice with streptozotocin-induced diabetes through regulation of the glycolytic pathway

Dysfunction of spermatogenesis is a major complication of diabetes mellitus (DM). This study characterized the protective effects of Dendrobium nobile-derived polysaccharides (DNP) against spermatogenetic dysfunction in mice with streptozotocin (STZ)-induced diabetes. The diabetic mice had lower body and testicular mass, and fewer spermatozoa with a higher incidence of malformation. The testicular histology showed disordered narrow seminiferous tubules covering a smaller area, and fewer spermatogenic cells. Moreover, the qRT-PCR analysis indicated that DM was associated with high expression of the pro-apoptotic factor Bax and low expression of the anti-apoptotic factor Bcl-2 in the testes. The qRT-PCR and immunohistochemical analysis clarified that DM was also associated with low testicular expression of the Sertoli cell (SC) markers GATA-4, WT1, and vimentin, and genes encoding the glycolytic rate-limiting enzymes LDHA, PKM2, and HK2. DNP treatment increased the body and testicular masses, sperm count, and number of spermatogenic cells of the mice, and reduced the proportion of abnormal sperm. DNP also reduced the expression of Bax, and increased that of Bcl-2, GATA-4, WT1, vimentin, LDHA, PKM2, and HK2, in the testes of the diabetic mice. Thus, DNP protects against spermatogenic dysfunction in diabetic mice by inhibiting apoptosis and activating the glycolytic pathway in their testes. •DNP treatment alleviates the histology of the testis and epididymis of diabetic mice.•DNP ameliorates the apoptosis of spermatogenic cells in testes of diabetic mice.•DNP recovers the number and function of testicular Sertoli cells in diabetic mice.•DNP enhances the expression of genes encoding rate-limiting glycolytic enzymes in testes of diabetic mice.