Effect of alpha lipoic acid on GDF9 and BMP15 expression in rat ovary in an experimental polycystic ovarian syndrome model

Objective: This thesis aims to histologically evaluate the potential protective effects of alphalipoic acid (ALA) on the ovarian tissue of female rats with experimentally induced polycystic ovary syndrome (PCOS) and to investigate its effects on the expression levels of growth and differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) genes, which play an important role in the folliculogenesis process, in ovarian tissue. Material and Methods: A total of 40 female Sprague-Dawley rats, 21 days old, were used in the study. The rats were divided into four groups: 7 in the Control group, 9 in the ALA group, and 12 each in the PKOS and PKOS+ALA groups. The Control group received 0.2 mL of sesame oil subcutaneously for 28 days. The PKOS group received 6 mg/100 g of dehydroepiandrosterone (DHEA) dissolved in 0.2 mL of sesame oil, administered subcutaneously for 28 days. The ALA group received a single daily oral dose of 100 mg/kg of ALA, prepared in sterile distilled water, for 28 days. The PKOS+ALA group received both DHEA (6 mg/100 g in 0.2 mL sesame oil, subcutaneously) and ALA (100 mg/kg, orally in sterile distilled water) for 28 days. At the end of the 28-day period, euthanasia was performed, and ovarian tissue samples were collected. Sections from these samples were stained using Crossman's triple staining method to examine general histological structure. The AvidinBiotin Peroxidase Method was employed for immunohistochemical analysis to determine the expression profiles of GDF9 and BMP15 proteins in ovarian tissues. Quantitative real-time PCR (qRT-PCR) and Western blot analyses were used to assess the gene expression of GDF9 and BMP15 at the transcriptional and translational levels. Results: Histological and histomorphometric analyses showed that the PKOS group contained a greater number of cystic and atretic follicles compared to the PKOS+ALA, ALA, and Control groups. Immunohistochemical analysis revealed similar expression profiles of GDF9 and BMP15 proteins across all groups. Real-time PCR results indicated that compared to the Control group, the PKOS group had a 2.16-fold (p 0,0012) decrease in GDF9 mRNA expression, while the PKOS+ALA and ALA groups showed 1.73-fold (p 0,099) and 2.15-fold (p 0,017) increases, respectively. Compared to the PKOS group, the increases in GDF9 mRNA levels in the PKOS+ALA (p 0,006) and ALA (p 0,002) groups were statistically significant. BMP15 mRNA levels in the PKOS group were 2.53-fold lower (p 0,004) than in the Control group, while the PKOS+ALA and ALA groups showed 1.39- and 1.82-fold increases, respectively; however, these differences were not statistically significant (p > 0,05). Nonetheless, when compared to the PKOS group, the increases in BMP15 mRNA expression in the PKOS+ALA (p 0,004) and ALA (p 0,003) groups were statistically significant. Western blot analysis showed that GDF9 protein levels decreased by 1.25- and 1.17-fold in the PKOS and PKOS+ALA groups, respectively, and increased by 1.03-fold in the ALA group compared to the Control (p > 0,05). Similarly, BMP15 protein levels decreased by 1.28- and 1.20-fold in the PKOS and PKOS+ALA groups, respectively, and increased by 1.08-fold in the ALA group (p > 0,05). Conclusion: The results suggest that ALA has a beneficial effect on the expression of GDF9 and BMP15 in the ovarian tissue of rats with DHEA-induced PKOS. The positive influence of ALA on the alterations observed in PKOS indicates its potential benefit in promoting ovarian follicular development.