Changes in Ovarian Stroma and Serum Reproductive Hormones in Rat Model of Polycystic Ovarian Syndrome Following Benzo[a]pyrene Toxicity
Francis Okpanachi Enemali
Neuroendocrinology Lab, Department of Anatomy, Faculty of Basic Medical Sciences, College of Health Sciences, University of Ilorin, Ilorin, Nigeria.
Aisha Oloruntobi Balogun
Neuroendocrinology Lab, Department of Anatomy, Faculty of Basic Medical Sciences, College of Health Sciences, University of Ilorin, Ilorin, Nigeria.
Rofiat Oyebola Taofeek
Neuroendocrinology Lab, Department of Anatomy, Faculty of Basic Medical Sciences, College of Health Sciences, University of Ilorin, Ilorin, Nigeria.
Oluwatosin Alaba Fowora
Neuroendocrinology Lab, Department of Anatomy, Faculty of Basic Medical Sciences, College of Health Sciences, University of Ilorin, Ilorin, Nigeria.
Oluwole Busayo Akinola *
Neuroendocrinology Lab, Department of Anatomy, Faculty of Basic Medical Sciences, College of Health Sciences, University of Ilorin, Ilorin, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Polycystic ovarian syndrome (PCOS) is a multisystem endocrine disorder characterised by hyperandrogenism, ovulatory dysfunction, and abnormalities in ovarian cytoarchitecture. Pathological extracellular matrix (ECM) remodelling and stromal fibrosis contribute to follicular arrest and increased tissue rigidity. However, the role of the environmental xenobiotic benzo[a]pyrene (BaP) in modulating stromal alterations and reproductive hormone profiles within a hyperandrogenic microenvironment remains largely undefined. This study investigated the interaction between testosterone-induced hyperandrogenism and low-dose BaP exposure in relation to ovarian stromal remodelling and gonadotropin profiles.
Fifteen prepubertal female Wistar rats (40–50 g) were randomly assigned to three experimental groups: Control (subcutaneous corn oil), PCOS (10 mg/kg/day testosterone propionate), and PCOS+BaP (10 mg/kg/day testosterone propionate and 10 µg/kg/day BaP) for 28 days. Serum concentrations of luteinising hormone (LH), follicle-stimulating hormone (FSH), and testosterone were quantified using enzyme-linked immunosorbent assays (ELISAs), and ovarian tissues were stained using the Gordon and Sweet technique for reticular fibre visualisation.
Somatic growth and serum LH and FSH levels did not differ significantly across groups (p > 0.05). Histopathological analysis, however, showed that both the PCOS and PCOS+BaP groups exhibited multiple cystic follicles and follicular arrest. The PCOS+BaP group had the highest percentage area of reticular fibres within the theca externa (60.70% ± 10.31%), compared with the PCOS group (39.94% ± 3.63%) and the control group (32.84% ± 2.80%). The PCOS+BaP group differed significantly from the control group (p < 0.05) but not from the PCOS group. These microstructural alterations occurred without significant between-group differences in serum LH or FSH at terminal sacrifice.
These findings indicate that BaP co-exposure was associated with greater ovarian stromal reticular fibre deposition and more pronounced structural alterations in the testosterone-induced PCOS model.
Keywords: Polycystic ovarian syndrome, Benzo[a]pyrene, ovarian stroma, fibrosis, reticular fibres, endocrine disruption