Abstract
Study question
Does high-dose testosterone therapy affect the stage distribution, morphological health and DNA damage repair capacity of human ovarian follicles and their survival in vitro?
Summary answer
Testosterone exposure is associated with reduced follicle growth activation, reduced follicle health and increased DNA damage: these further deteriorate after six days of culture. What is known already: Androgens have diverse actions within the ovary, however, there is a lack of information regarding the long-term effects of high-dose testosterone on ovarian function and reproductive potential. Cumulus-oocyte complexes recovered from transgender men have been successfully matured in-vitro but little is known regarding the impact of this gender affirming endocrine therapy on the primordial follicle pool. Study design, size, duration: Whole ovaries were obtained from four transgender men aged 25–36 years with informed consent at oophorectomy. All patients had received 1000mg testosterone undecanoate intramuscularly at 12–16 week intervals for a minimum of 4 years pre-operatively. Cortical tissues were dissected into small pieces (≈1x1x0.5mm) and either immediately fixed for histological analysis or cultured for 6 days. Testosterone-treated ovaries were compared to cortical biopsies from age-matched healthy women obtained at caesarean section (n = 4, age 26–36). Participants/materials, setting, methods: Follicle number, classification of developmental stage and morphology were evaluated by histological analysis of ovarian cortical tissue from day 0 and 6 days post culture. Immunohistochemical analysis included γH2AX as a marker of DNA damage, and meiotic recombination 11 (MRE11), ataxia telangiectasia mutated (ATM) and Rad51 as DNA repair proteins. A total of 3802 follicles from testosterone exposed and 878 from control ovaries were analysed. Main results and the role of chance: At day 0 (D0), transgender tissue had a higher proportion of non-growing follicles (92.7±1.7%) compared to control (85.4±6.2%, p < 0.05) but a lower proportion of morphologically healthy follicles (non-growing 59%, primary 61%, secondary 36%; vs 83%, 75%, 80% in controls, all p < 0.005). After 6 days in culture, the proportion of growing follicles increased (51.3% vs 46.5%) but follicle health further declined (all stages p < 0.005).
DNA damage was assessed by expression of γH2AX. At D0, the proportion of oocytes showing DNA damage was significantly higher in transgender non-growing follicles (48.1±12.5%, vs 12.3±0.25%, p < 0.005). After culture, γH2AX expression increased in both transgender (p < 0.005) and controls (p < 0.005) but remained higher in transgender oocytes (non-growing 72.2%, primary 71.7% vs 27.3%, 46.2%, all p < 0.05). At D0, there was no difference in expression of DNA repair enzymes ATM and RAD51 between transgender and control oocytes, and increased expression of MRE11 in control non-growing follicles (p < 0.05). Post-culture, there was a significant increase in ATM expression in transgender non-growing oocytes compared to control (98.5% vs 77.8%, p < 0.05) and a less marked decline in RAD51 expression(p < 0.05). The expression of MRE–11 in control non-growing oocytes dramatically declined (100% to 58.2%, p < 0.05), unlike in transgender tissue where expression was comparable to D0.
Limitations, reasons for caution
A large number of follicles have been analysed, but only from a small number of ovaries. DNA damage at D0 and after 6 days of culture may not reflect DNA damage and repair capacity at later stages of follicle growth. The effect of duration of testosterone treatment was not investigated.
Wider implications of the findings: These data indicate that high circulating concentrations of testosterone have previously unrecognised effects on the primordial and small-growing follicles of the ovary. These results may have implications for transgender men receiving gender-affirming therapy prior to considering pregnancy or fertility preservation measures.
Trial registration number
n/a
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