Parental Testosterone Treatment Induces Multi-Generational Reproductive and Metabolic Effects in a Mouse Model of Gender-Affirming Hormone Therapy

Robin E. Kruger1,2, Daniel Pfau1,2, Vasantha Padmanabhan1,2,4, Molly Moravek5,6, Ariella Shikanov1,3,7 

1Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, MI, USA
2Department of Pediatrics, University of Michigan, Ann Arbor, MI, USA
3Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
4Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
5Department of Women’s Heath, Henry Ford Health, Rochester Hills, MI, USA
6Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University, East Lansing, MI, USA
7Department of Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI, USA


Abstract Text: An estimated 1.6 million Americans identify as transgender, non-binary, and gender diverse (TNG). Although gender-affirming hormone therapy (GAHT) is established as a safe and effective standard-of-care therapy for gender dysphoria experienced by many TNG patients, surprisingly little is known about the long-term effects of GAHT on diverse body systems such as reproduction and metabolism. There are also no clinical standards for how long, if at all, testosterone (T)-GAHT should be paused before pursuing assisted reproductive technologies or natural conception. Given this paucity of data, the TNG community has identified the effect of GAHT on future reproductive capacity and offspring health as a priority for research. Since controlled studies of GAHT cannot be ethically performed with human patients, our lab has developed a mouse model of T-GAHT to model a transmasculine GAHT regimen. Using this model, we tested the hypothesis that testosterone treatment in dams before fertilization would lead to adverse metabolic and reproductive effects in offspring. We implanted intact adult female CD-1 mice with capsules containing 10 mg T for 12 weeks. After treatment, mice either underwent ovarian stimulation and oocyte retrieval to produce pups by IVF (n=20 dams) or capsules were removed and females were paired with breeder males to produce pups by natural breeding (n=15 dams). Male and female pups from each group (n=10/group, from 3-6 dams) were evaluated from pubertal onset to adulthood. All statistical significance was evaluated by Student’s t-test with p< 0.05. T-treated dams showed decreased weight gain over the treatment period, increased heart and liver weight, decreased liver lipid accumulation, decreased fat pad weight, and increased circulating triglycerides. T-treated dams also displayed significant reproductive effects including decreased litter size (natural breeding), increased uterine weight with decreased expression of gonadotropin receptors, and increased ovarian weight with more atretic follicles and fewer corpora lutea. Both male and female pups from T-treated dams demonstrated precocious pubertal onset (natural breeding) and decreased weight (IVF). Female pups from T-treated dams also displayed decreased fat deposition and increased ovarian weight, though follicle counts and estrus cycle were unaffected. These studies suggest that prior T-treatment may have a negative effect on fertility and offspring phenotypes, though the functional effect on offspring health is still unclear. Encouragingly, many of these effects were undetectable in a second litter, suggesting that these effects may be mitigated by a cessation of T-GAHT before pursuing biological parenthood. This work is supported by the National Institutes of Health R01 HD098233-01 to M.M. and T32 DK071212 to R.E.K. and D.P. Additional support from NIH P30 DK020572 (Michigan Diabetes Research Center).