(965.1) Administration of Estradiol in Young Adulthood in the Male Sprague Dawley Rat to Mimic Female Physiological Levels is Associated with a Reduction in Body Weight, Lean Mass and Testicular Size

Poster Board Number: E669

Barbara Alexander (University of Mississippi Medical Center), Adam Rawls (University of Mississippi Medical Center), Kathy Cockrell (University of Mississippi Medical Center), Kacey Davenport (University of Mississippi Medical Center), Norma Ojeda (University of Mississippi Medical Center), Jane Reckelhoff (University of Mississippi Medical Center), Licy Yanes Cardozo (University of Mississippi Medical Center), Noha Shawky (University of Mississippi Medical Center)

Transgender females are biological males at birth but identify as female by gender. The prevalence of the transgender population is increasing, yet the burden of increased cardiovascular (CV) risk is unclear. Sex is an independent predictor of CV risk but the role of sex hormones in mediating CV disease in the transgender population is unknown. Gender affirming therapy (GAT) in transfemales (male to female) involves administration of estradiol with a goal to achieve the female physiological range of estrogen. The aim of this study was to optimize estradiol levels in a rat model of GAT. Male Sprague Dawley (SD) rats were implanted with silastic capsules to deliver 17-beta estradiol benzoate (E2) at doses of 2.5 (Low), 5 (Medium) and 7.5 (High) mg/day versus empty pellet (EP) starting at 13 weeks of age (n=4/group). At 16 weeks of age, E2 was determined by ELISA, lean and fat mass were measured via EchoMRI, and creatinine, BUN, lipids and liver enzymes were quantitated by Chemistry Analyzer. The different doses of E2 were compared to EP using unpaired t test (GraphPad) with plt;0.05 considered significant. All doses of E2 caused significant increases in circulating estradiol versus EP (Table, plt;0.001) that were equivalent to estradiol levels in age-matched female SD rats as previously reported by our laboratory (PMID: 17724277). Food intake, body weight, and lean mass, were significantly reduced after 3 weeks of E2 compared to EP (Table, plt;0.001). Administration of E2 was also associated with a significant reduction in testicular weight versus EP (Table, plt;0.001).  To conclude, optimization of E2 levels in the male rat is critical to the development of a rodent model that mimics GAT in male to female transgender. The use of a transfemale rodent model will allow study of the pathophysiology of increased CV risk associated with GAT across the lifespan.

Support or Funding Information

HL-143459, HL135089, P20-GM-104357, P20-GM121334, LGBTQ Fund of MS

HL-143459, HL135089,lt;bgt;amp;nbsp;lt;/bgt;P20-GM-104357, P20-GM121334, LGBTQ Fund of MS



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