Abstract
Disclosure: N.S. Aquino: None. A. Campideli-Santana: None. L.M. Antunes: None. R. Araújo-Lopes: None. K.S. Silva: None. P.C. Henriques: None. D.D. Gusmão: None. M.P. Bernuci: None. R.E. Szawka: None. A.M. dos Reis: None. Polycystic Ovary Syndrome (PCOS) is a high-prevalent endocrine dysfunction, causing metabolic disorders and infertility. Women with PCOS show a disrupted hypothalamus-pituitary-gonadal (HPG) axis, which results in increased luteinizing hormone (LH) secretion, LH pulse frequency, and LH/follicle stimulating hormone (FSH) ratio. These changes are related to an impaired negative-feedback effect of ovarian steroids, estradiol and progesterone, on the gonadotrophin releasing-hormone (GnRH) neurons. Because the kisspeptin/neurokinin-B/dynorphin (KNDy) neurons of the arcuate (ARC) nucleus are responsible for mediating the ovarian steroid negative feedback, we investigated whether the ablation of KNDy neurons would change the LH secretion and ovarian morphology in a rat model of PCOS. Pregnant dams were treated with dihydrotestosterone (DHT, 3 mg/day; s.c) from days 16 to 19 of pregnancy. Three months after birth, the prenatally androgen-treated (PNA) offspring received intra-ARC stereotaxic injections of the neurokinin-3 receptor agonist conjugated with saporin (NK3-SAP) to induce the lesion of KNDy neurons and were submitted to serial blood sampling for LH measurement. PNA NK3-SAP rats had a moderate loss of ARC neurokinin-B-immunoreactive neurons (between 50-70%) compared with the Blank-SAP-injected PNA group. The PNA Blank-SAP rats displayed LH pulse frequency, pulse amplitude, and mean LH levels similar to control rats on diestrus. Remarkably, the partial loss of KNDy neurons increased the LH pulse amplitude and mean LH without changing the pulse frequency. Histological analysis was performed to investigate the outcome of the partial loss of KNDy neurons on the ovarian morphology in PNA rats. The numbers of primordial, primary, and secondary health follicles were decreased in PNA Blank-SAP compared with diestrus rats. Notably, the number of primordial follicles was partially restored in NK3-SAP rats. On the other hand, neither the number of atretic follicles nor the number of corpora lutea was changed in PNA Blank or NK3-SAP rats, indicating no change in the ovulatory function. Therefore, we provide evidence that KNDy neurons negatively modulate LH release and LH pulse amplitude in PNA rats. Moreover, the results suggest that KNDy neurons are involved in the reduction of the primordial follicle pool and ovarian reserve in PNA rats. Financial Support: Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), Brazilian National Council for Scientific and Technological Development (CNPq), British Society for Neuroendocrinology (BSN). Presentation: Friday, June 16, 2023