Makayla Nesbitt
Pronouns: She/Her/Hers
Research Mentor(s): Vasantha Padmanabhan
Research Mentor School/College/Department: Pediatrics / Medicine
Program: UROPF
Session: Session 6 (3:40pm – 4:30pm)
Authors: Makayla Nesbitt , Vasantha Padmanabhan, Katherine Halloran
Abstract
Polycystic ovary syndrome (PCOS) is a disorder characterized by excess androgens and is linked to reproductive and metabolic dysfunction including insulin resistance and compensatory hyperinsulinemia. The use of animal models helps address the underlying mechanisms by which excess androgens contribute to development of disease states. Sheep are precocial, typically have 1-2 offspring, and have similar in utero developmental trajectory as humans, and hence are of translational relevance. Testosterone (T) treatment of pregnant sheep from day 30-90 of pregnancy (the sexually dimorphic window of fetal development, where male fetuses naturally see higher levels of testosterone compared to females) leads to metabolic dysfunction in female offspring, including insulin resistance and compensatory hyperinsulinemia during adulthood similar to women with PCOS. The early effect of T treatment is manifested as decreased pancreatic weights and reduced pancreatic:fetal weight ratios and increases in apoptosis of beta cells in day 90 female fetuses (term 147 days). Considering women are more insulin sensitive than men, we hypothesized that the pancreatic defects seen in prenatal T-treated female sheep will be similar to control males, as males naturally see an increase in testosterone during this period. In this study, we are addressing the effects of prenatal T-induced changes that contribute to pancreas compromise to determine 1) if effects of prenatal T on pancreas development persists after the cessation of T treatment, 2) if T treated female fetuses are more similar to males, and 3) if excess T exacerbates the male phenotype. Pregnant ewes were treated with either T propionate (T; 100 mg in 2 ml corn oil) or vehicle (C) between days 30-90 of pregnancy. Ewes were euthanized on day 120 of pregnancy to obtain female (F) and male (M) fetuses from control and T-treated mothers, resulting in 4 groups: CF, TF, CM, TM. Fetuses were weighed and pancreas tissues were collected, weighed, and either processed for paraffin embedding or frozen and stored at -80oC. The paraffin blocks will be sectioned at 5 µm, mounted on slides, then used for immunofluorescent staining to localize insulin-positive cells. Pancreatic collagen content will also be assessed with a Sircol dye binding assay using frozen tissue. The results of the proposed experiments will help determine if T females mirror control males and if excess T influences the male phenotype. This will help provide a foundation to address how early exposure to excess androgens contribute to metabolic syndrome in adult life. This work is supported by The National Institute of Health Grants R01 HD099096 and R01 HL139369.
