Nicotinamide mononucleotide improves spermatogenic function in streptozotocin-induced diabetic mice via modulating the glycolysis pathway.

Spermatogenic dysfunction is one of the major secondary complications of diabetes; however, the underlying mechanisms remain ill-defined, and there is no available drug or strategy for the radical treatment of diabetic spermatogenic dysfunction. Therefore, the objective of this study is to investigate the protective effects of nicotinamide mononucleotide (NMN) on testicular spermatogenic function in streptozotocin (STZ)-induced diabetic mice. The results show that oral administration of NMN significantly increases the body and testis weight and the number of sperms. Moreover, the abnormal sperm count and the rate of sperm malformation are significantly decreased compared with the saline-treated diabetic mice. Histological analysis reveals that NMN treatment significantly increases the area and diameter of seminiferous tubules, accompanied by an increased number of spermatogenic cells and sperms. Immunohistochemistry and qRT-PCR results show that NMN increases Bcl-2 expression and decreases Bax expression in the testis. NMN also increases the protein expression of Vimentin and the mRNA expressions of WT1 and GATA4. In addition, qRT-PCR, western blot analysis and immunohistochemistry results also show that NMN increases the expressions of glycolysis-related rate-limiting enzymes including HK2, PKM2, and LDHA. In summary, this study demonstrates the protective effects of NMN on the testis in an STZ-induced diabetic mice model. NMN exerts its protective effects via reducing spermatogenic cell apoptosis by regulating glycolysis of Sertoli cells in diabetic mice. This study provides an experimental basis for the future clinical application of NMN in diabetes-induced spermatogenic dysfunction.

Mogroside V Improves Follicular Development and Ovulation in Young-Adult PCOS Rats Induced by Letrozole and High-Fat Diet Through Promoting Glycolysis.

Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine disorder characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovaries. In this study, we induced a young-adult PCOS rat model by oral administration of letrozole combined with a high-fat diet and then treated with mogroside V (MV) to evaluate the protective effects of MV on endocrine and follicle development in young-adult PCOS rats. MV (600 mg/kg/day) administration not only significantly reduced the body weight and ovary weight, but also attenuated the disrupted estrous cycle and decreased the level of testosterone. MV restored the follicular development, especially by increasing the number of corpus luteum and the thickness of the granular layer in young-adult POCS rats. Moreover, metabolomics showed that MV markedly increased the levels of D-Glucose 6-phosphate, lactate and GTP, while decreased the level of pyruvate. Bioinformatic analysis revealed that MV recovered multiple metabolism-related processes including gluconeogenesis, glycolysis and glucose metabolic process. Further real-time quantitative PCR analysis showed that MV upregulated the expression of lactate dehydrogenase A (Ldha), hexokinase 2 (Hk2) and pyruvate kinase M2 (Pkm2). Western blotting and immunohistochemistry analysis showed that MV restored the expression of lactate dehydrogenase A (Ldha), hexokinase 2 (Hk2) and pyruvate kinase M2 (Pkm2). Collectively, these findings indicated that MV could effectively improve the ovarian microenvironment by upregulating the expression of LDHA, HK2 and PKM2 in granulosa cells and enhancing lactate and energy production, which may contribute to follicle development and ovulation of young-adult PCOS rats.

Resveratrol regulates insulin resistance to improve the glycolytic pathway by activating SIRT2 in PCOS granulosa cells.

Scope: Insulin resistance (IR) has a close relationship with the main clinical manifestations of patients with PCOS; hence, the research and development of new drugs to treat PCOS by improving IR is a desiderate task at present. Resveratrol (RES) possesses a variety of beneficial pharmacological functions, such as antioxidation, anti-inflammatory, regulating glucose, and lipid metabolism. However, whether RES could improve IR and the underlying mechanisms remained unclear in PCOS. Methods and results: SD rats received a high-fat diet and letrozole for 30 days to establish the PCOS model and then intervened with RES for 30 days. The results demonstrated that RES played a protective role on the IR in PCOS rats, which significantly decreased the levels of blood glucose and serum insulin, up regulated the expression of IGF1R, and down regulated the expression of IGF1. In vitro, KGN cells were treated with insulin, RES, and AGK2, respectively. We found that a high dose of insulin (4µg/mL) significantly inhibited KGN cell viability, decreased the level of lactic acid, and increased the level of pyruvate, while RES (25µM) attenuated the growth-inhibitory effect, as well as increased the level of lactic acid and decreased the level of pyruvate after high levels of insulin treatment. Simultaneously, RES up regulated the expression level of the crucial rate-limiting enzymes relating to glycolytic pathways, such as LDHA, HK2, and PKM2. Furthermore, AGK2 remarkably inhibited the expression level of SIRT2, which was similar to the same negative effects processed by insulin. Meanwhile, RES overtly repaired the glycolysis process by reversing the levels of lactic acid and pyruvate, together with up regulating the expression level of LDHA, HK2, and PKM2, after AGK2 treatment. Conclusion: RES could effectively improve insulin resistance and restore the glycolysis pathway by regulating SIRT2, which may contribute to attenuating the ovarian damage of PCOS rats and provide a potential treatment for patients with PCOS.

Icariin improves testicular dysfunction via enhancing proliferation and inhibiting mitochondria-dependent apoptosis pathway in high-fat diet and streptozotocin-induced diabetic rats.

BACKGROUND: Diabetes mellitus (DM), a chronic metabolic disease, severely impairs male reproductive function. However, the underpinning mechanisms are still incompletely defined, and there are no effective strategies or medicines for these reproductive lesions. Icariin (ICA), the main active component extracted from Herba epimedii, is a flavonoid traditionally used to treat testicular dysfunction. Whether ICA can improve male reproductive dysfunction caused by DM and its underlying mechanisms are still unclear. In this study, by employing metformin as a comparative group, we evaluated the protective effects of ICA on male reproductive damages caused by DM and explored the possible mechanisms. METHODS: Rats were fed with a high fat diet (HFD) and then intraperitoneally injected with streptozotocin (STZ) to induce diabetes. Diabetic rats were randomly divided into T2DM + saline group, T2DM + metformin group and T2DM + ICA group. Rats without the treatment of HFD and STZ were used as control group. The morphology of testicular tissues was examined by histological staining. The mRNA expression levels were determined by quantitative real-time PCR. Immunostaining detected the protein levels of proliferating cell nuclear antigen (PCNA), hypoxia-inducible factor 1-alpha (HIF-1α) and sirtuin 1 (SIRT1) in testicular tissues. TUNEL assay was performed to determine cell apoptosis in the testicular tissues. The protein expression levels of HIF-1α and SIRT1 in the testicular tissues were determined by western blot assay. RESULTS: ICA effectively improved male reproductive dysfunction of diabetic rats. ICA administration significantly decreased fasting blood glucose (FBG) and insulin resistance index (IRI). In addition, ICA increased testis weight, epididymis weight, sperm number, sperm motility and the cross-sectional area of seminiferous tubule. ICA recovered the number of spermatogonia, primary spermatocytes and Sertoli cells. Furthermore, ICA upregulated the expression of PCNA, activated SRIT1-HIF-1α signaling pathway, and inhibited intrinsic mitochondria dependent apoptosis pathway by upregulating the expression of Bcl-2 and downregulating the expression of Bax and caspase 3. CONCLUSION: These results suggest that ICA could attenuate male reproductive dysfunction of diabetic rats possibly via increasing cell proliferation and decreasing cell apoptosis of testis. ICA potentially represents a novel therapeutic strategy against DM-induced testicular damages.

Resveratrol Improves Follicular Development of PCOS Rats by Regulating the Glycolytic Pathway.

SCOPE: Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder that can cause infertility; however, the underlying mechanisms remain ill-defined, and there are no available drugs or strategies for the treatment of PCOS. This study examined the therapeutic effect of resveratrol in a rat model of PCOS. METHODS AND RESULTS: PCOS is induced in rats by administration of letrozole and a high fat diet to determine whether resveratrol has a protective effect. Oral administration of resveratrol significantly decreased body weight, as well as the serum levels of testosterone and follicle stimulating hormone. Resveratrol improved the estrous cycle by restoring the thickness and number of granular cells. Resveratrol increased the levels of lactate and ATP, decreased pyruvate levels, and restored the glycolytic process, upregulating LDHA, HK2, and PKM2. Resveratrol also upregulated SIRT2, thereby modulating the expression of rate-limiting enzymes of glycolysis. CONCLUSION: Resveratrol suppressed damage to the ovaries in PCOS rats by restoring glycolytic activity, providing potential targets for the treatment of PCOS.

Dendrobium nobile Lindl. polysaccharides improve follicular development in PCOS rats.

Polycystic ovary syndrome (PCOS) is the most typical and common metabolic abnormalities in women of reproductive age. This study examined the protective effects of Dendrobium nobile Lindl. polysaccharides (DNLP) on ovarian follicular development in letrozole-induced PCOS rats and explored the underlying molecular mechanisms. The PCOS rats showed the increased body weight, serum testosterone and luteinizing hormone levels and insulin resistance. DNLP treatment reduced the body weight, serum testosterone level and insulin resistance, but failed to affect luteinizing hormone level in the PCOS rats. DNLP treatment recovered disrupted estrous cycle in the PCOS rats. DNLP treatment decreased antral follicles and increased the thickness of the granular cell layer. DNLP treatment increased the PCNA mRNA and protein expression levels in the PCOS ovarian tissues, and inhibited cell apoptosis in the PCOS ovarian tissues via regulating apoptosis-related proteins including Bax, Bcl-2 and caspase-3. In summary, this study demonstrated the protective effects of DNLP on the ovaries in the letrozole-induced PCOS rat model. DNLP exerted its protective effects via improving follicular development and inhibiting apoptosis of ovarian granular cells in PCOS rats. This study will provide experimental basis for the future clinical application of DNLP in the treatment of PCOS.