Alpha-ketoglutarate ameliorates induced premature ovarian insufficiency in rats by inhibiting apoptosis and upregulating glycolysis.

RESEARCH QUESTION: What are the effects of alpha-ketoglutarate (α-KG) treatment on the ovarian morphology and ovarian reserve function of rats with cyclophosphamide (CTX)-induced premature ovarian insufficiency (POI)? DESIGN: Thirty female Sprague Dawley rats were randomly allocated to a control group (n = 10) and a POI group (n = 20). Cyclophosphamide was administered for 2 weeks to induce POI. The POI group was then divided into two groups: a CTX-POI group (n = 10), administered normal saline, and a CTX-POI + α-KG group (n = 10), administered α-KG 250 mg/kg per day for 21 days. Body mass and fertility was assessed at the end of the study. Serum samples were collected for hormone concentration measurement, and biochemical, histopathological, TUNEL, immunohistochemical and glycolytic pathway analyses were conducted for each group. RESULTS: The α-KG treatment increased body mass and ovarian index of rats, partially normalized their disrupted estrous cycles, prevented follicular loss, restored ovarian reserve, and increased pregnancy rate and litter sizes of rats with POI. It significantly reduced serum concentration of FSH (P < 0.001), increased that of oestradiol (P<0.001) and reduced apoptosis of granulosa cells (P = 0.0003). Moreover, α-KG increased concentrations of lactate (P = 0.015) and ATP (P = 0.025), reduced that of pyruvate (P<0.001) and increased expression of rate-limiting enzymes of glycolysis in the ovary. CONCLUSIONS: α-KG treatment ameliorates the deleterious effects of CTX on the fertility of female rats, possibly by reducing the apoptosis of ovarian granulosa cells and restoring glycolysis.

Follicular fluid-derived exosomal miR-143-3p/miR-155-5p regulate follicular dysplasia by modulating glycolysis in granulosa cells in polycystic ovary syndrome.

OBJECTIVE: Polycystic ovary syndrome (PCOS) is characterized by follicular dysplasia. An insufficient glycolysis-derived energy supply of granulosa cells (GCs) is an important cause of follicular dysplasia in PCOS. Follicular fluid (FF) exosomal microRNAs (miRNAs) have been proven to regulate the function of GCs. In this study, exosomes extracted from clinical FF samples were used for transcriptome sequencing (RNA-seq) analysis, and a human ovarian granulocyte tumour cell line (KGN cells) was used for in vitro mechanistic studies. METHODS AND RESULTS: In FF exosomal RNA-seq analysis, a decrease in glycolysis-related pathways was identified as an important feature of the PCOS group, and the differentially expressed miR-143-3p and miR-155-5p may be regulatory factors of glycolysis. By determining the effects of miR-143-3p and miR-155-5p on hexokinase (HK) 2, pyruvate kinase muscle isozyme M2 (PKM2), lactate dehydrogenase A (LDHA), pyruvate, lactate and apoptosis in KGN cells, we found that upregulated miR-143-3p expression in exosomes from the PCOS group inhibited glycolysis in KGN cells; knockdown of miR-143-3p significantly alleviated the decrease in glycolysis in KGN cells in PCOS. MiR-155-5p silencing attenuated glycolytic activation in KGN cells; overexpression of miR-155-5p significantly promoted glycolysis in KGN cells in PCOS. In this study, HK2 was found to be the mediator of miR-143-3p and miR-155-5p in FF-derived exosome-mediated regulation of glycolysis in KGN cells. Reduced glycolysis accelerated apoptosis of KGN cells, which mediated follicular dysplasia through ATP, lactate and apoptotic pathways. CONCLUSIONS: In conclusion, these results indicate that miR-143-3p and miR-155-5p in FF-derived exosomes antagonistically regulate glycolytic-mediated follicular dysplasia of GCs in PCOS. Video Abstract.