Investigation into the effects of sodium valproate on prepubertal mouse gonads in vivo

Objective Sodium valproate (SV) is a widely used anti-epileptic drug with well-established reproductive and teratogenic effects, yet its impact on the developing prepubertal reproductive system remains poorly understood. This study investigated the effects of prepubertal SV exposure on gonadal development, including folliculogenesis, testicular architecture and steroidogenic gene expression in male and female mice in vivo. Methods CD1 mouse pups received intraperitoneal injections of saline (control), low or high dose SV (50 or 100 mg/kg, respectively) on postnatal days (PND) 6, 8, and 10. On PND17 the animals were culled and gonads dissected. Ovaries and testes were assessed histologically using haematoxylin and eosin staining. Ovarian follicle number, stage and health were quantified. Testicular tubule morphology and key testicular cell numbers (germ, Sertoli, spermatogonial stem cells, and interstitial/Leydig cells) were evaluated using immunofluorescence with automated image analysis. Expression of key steroidogenic genes (CYP11A1, STAR, CYP19A1 in ovaries; INSL3, STAR, CYP11A1 in testes) was measured by RT-qPCR. Results SV exposure did not significantly affect ovarian follicle number, distribution or health. Testicular morphology and the density of Sertoli, spermatogonial stem cells, and interstitial cells were likewise unaffected. However, a dose-dependent trend toward reduced germ cell density was observed in males at a high dose SV, though this did not reach statistical significance (P = 0.058). Steroidogenic gene expression was unaffected by SV exposure in both ovaries and testes across all treatment groups. Significance This study provides the first in vivo assessment of short-term prepubertal SV exposure on gonadal development in both sexes. The overall findings suggest that brief SV exposure during the prepubertal window does not cause overt gonadotoxicity. Nonetheless, the trend toward reduced testicular germ cell density warrants further investigation with longer exposure durations and functional fertility endpoints, to better inform clinical risk assessment in paediatric patients receiving SV.