Polycystic ovary syndrome (PCOS) is associated with impaired ovarian steroidogenesis and ovulation, which necessitates the development of effective ovulation inducers for PCOS. The aim of the study was to evaluate the effects of allosteric luteinizing hormone receptor agonist TP03 and human chorionic gonadotropin (hCG) on ovarian steroidogenesis, as well as ovulation in prepubertal female rats with dehydroepiandrosterone(DHEA)-induced PCOS. Taking into account differences in progesterone levels, cohorts with high (PCOS(H)) and low (PCOS(L)) progesterone were formed and treated with Follimag and Cetrotide. After 48 h, TP03 (25 mg/kg) or hCG (25 IU/rat) were injected, and hormone levels, gene expression, and ovarian morphology were assessed. The PCOS(H)-cohort exhibited irregular estrous cycles, ovarian cysts, and increased ovarian mass and estradiol levels, but the number of corpora lutea (CL) was maintained. In the PCOS(L)-cohort, ovarian weight was increased, and Star, Cyp11a1, and Adamts1 gene expression as well as the CL number were decreased. In both cohorts, TP03 and hCG increased progesterone levels and the expression of steroidogenesis (Star, Cyp11a1) and ovulation (Cox2, Adamts1, Egr1) genes, as well as inducing CL formation. Thus, TP03, like hCG, stimulates steroidogenesis and ovulation in PCOS-rats with different progesterone levels, which provides the first evidence of the effectiveness of allosteric LHR agonists as ovulation triggers in PCOS.

BACKGROUND: Rodent models of polycystic ovary syndrome, including those induced by dehydroepiandrosterone, are widely used to study the pathogenesis of this disorder; however, ovarian steroidogenesis and ovulation markers in this model remain insufficiently characterized. There are no data on the ability of luteinizing hormone receptor agonists to stimulate ovulation in rats with this model of polycystic ovary syndrome, which is important for assisted reproductive technologies. AIM: This study aimed to investigate ovarian steroidogenesis, ovulation markers, and ovarian morphology in infantile female rats with dehydroepiandrosterone-induced polycystic ovary syndrome, and to assess the effects of the allosteric agonist TP03, 5-amino-N-tert-butyl-2-(methylsulfanyl)-4-(3-(nicotinamido)phenyl)thieno[2,3-d]pyrimidine-6-carboxamide, on these parameters. METHODS: Female Wistar rats, starting at 23–26 days of age, were treated with dehydroepiandrosterone for 6 weeks (6 mg/100 g/day, subcutaneously). The following parameters were assessed: body and ovarian weight, serum levels of testosterone, progesterone, and estradiol (enzyme-linked immunosorbent assay), ovarian gene expression (reverse-transcription polymerase chain reaction), and ovarian morphology (number of tertiary and preovulatory follicles, corpora lutea, and follicular cysts) by microscopy. Rats with polycystic ovary syndrome were stimulated with an ovulation-inducing drug at a dose of 15 IU/rat, followed by TP03 at a dose of 25 mg/kg 48 h later; the studied parameters were evaluated 16 h later. RESULTS: In dehydroepiandrosterone-induced rats, ovarian weight, the number of tertiary follicles and corpora lutea of previous cycles, progesterone levels, and the expression of genes responsible for steroidogenesis (Star, Cyp11a1, Cyp17a1) and ovulation (Adamts-1, Vegf-a) were decreased, whereas testosterone levels were increased and follicular cysts were detected in the ovaries, consistent with the pathogenesis of polycystic ovary syndrome. Treatment with ovulation-inducing drugs increased ovarian weight, progesterone levels, and Cyp17a1 gene expression, and stimulated ovulation, leading to the formation of corpora lutea. Luteinized unruptured follicles were also detected in the ovaries; this finding was associated with decreased expression of the ADAMTS-1 metalloproteinase and VEGF-A genes involved in follicular rupture. CONCLUSION: Treatment of infantile rats with dehydroepiandrosterone-induced polycystic ovary syndrome using TP03 induces ovulation; however, along with normal corpora lutea, luteinized unruptured follicles are formed as a result of decreased expression of genes involved in follicular rupture.