Moravek, M. | bioRxiv Science

bioRxiv2025

Functional Integration of Different-Sex Gonad Transplants into the Adult Mouse Hypothalamic Pituitary Gonadal Axis

Gender-affirming hormone therapy (GAHT) relies on exogenous hormones to produce hormonal milieus that achieve and/or maintain embodiment goals. Another potential route to these endpoints is transplantation of novel steroidogenic tissue. To develop a pre-clinical model, we asked whether different-sex gonad transplants can be functionally integrated into the adult mouse hypothalamic-pituitary-gonadal (HPG) axis. Adult male and female mice were gonadectomized and implanted with gonads from genetically matched but different-sex pups. Controls received gonads from same-sex pups. Temporal changes to gonadotropin and steroid hormone levels reveal the decoupling of the HPG following gonadectomy and gonad-dependent levels after transplanting donor gonads. After six weeks, histological structures in transplanted gonads were consistent with expected steroidogenesis and gametogenesis. Interestingly, pituitary, ARC and AVPV mRNA showed gonad- and sex-dependent expression patterns. Future work with this technique could lead to translation to gender affirming care and explorations of gonad-dependent sex differences in biomedical and basic research.

cell biology↗

bioRxiv2024

Functional Changes to Achilles Tendon and Enthesis in a Mouse Model of an Adolescent Masculine Gender-Affirming Hormone Treatment

Many transgender youth seek gender affirming care, such as puberty suppression, to prolong decision-making and to align their physical sex characteristics with their gender identity. During peripubertal growth, connective tissues such as tendon rapidly adapt to applied mechanical loads (e.g., exercise) yet if and how tendon adaptation is influenced by sex and gender affirming hormone therapy during growth remains unknown. The goal of this study was to understand the how pubertal suppression influences the structural and functional properties of the Achilles tendon using an established mouse model of transmasculine gender affirming hormone therapy. C57BL/6N female-born mice were assigned to experimental groups to mimic gender-affirming hormone therapy in human adolescents, and treatment was initiated prior to the onset of puberty (at postnatal day 26, P26). Experimental groups included controls and mice serially treated with gonadotropin release hormone analogue (GnRHa), delayed Testosterone (T), or GnRHa followed by T. We found that puberty suppression using GnRHa, with and without T, improved the overall tendon load capacity in female-born mice. Treatment with T resulted in an increase in the maximum load that tendon can withstand before failure. Additionally, we found that GnRHa, but not T, treatment resulted in a significant increase in cell density at the Achilles enthesis. NEW & NOTEWORTHYThese findings demonstrate that puberty suppression or testosterone does not negatively influence tendon structural or functional properties in a mouse model of transmasculine gender affirming care. In all treatment groups, the ability of the tendon to withstand load was significantly increased. Puberty suppression with GnRHa significantly increased enthesis cell density, suggesting an extended growth phase. These findings elucidate the effects of gender affirming care on the structural and functional properties of the tendon and enthesis.

physiology↗