Dose and duration dependent effects of borax on ovarian structure and function in female rats

Boron is an essential trace element with emerging physiological significance; however, its effects on the female reproductive system remain poorly characterized. Most available studies are limited to single-dose applications or short-term exposures. In this study, we investigated the dose and duration dependent effects of oral boron exposure on ovarian follicular reserve, apoptosis, and reproductive hormone profiles in female Wistar albino rats. Animals were assigned to low- and high-dose borax groups (1250 and 5000 mg/kg/day, respectively) and exposed for short-term (7 and 15 days) or long-term (30 and 60 days) periods. At the end of each exposure period, ovarian tissues were collected for histomorphometric evaluation, while apoptosis was assessed using the TUNEL assay. Serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), and anti-Müllerian hormone (AMH) were also measured. Histomorphometric analysis revealed a significant reduction in primordial and primary follicle numbers, indicating depletion of the ovarian reserve, particularly in the high-dose and long-term exposure groups. TUNEL analysis demonstrated a marked increase in apoptotic cell density in ovarian tissues following prolonged boron administration. In parallel, boron exposure induced significant dose and duration dependent alterations in circulating reproductive hormone levels. Collectively, these findings suggest that chronic and high-dose oral boron exposure adversely affects ovarian morphology and function through enhanced apoptotic activity and disruption of endocrine homeostasis. These results highlight the potential reproductive toxicity of long-term boron exposure and underscore the need for further molecular studies to clarify the underlying mechanisms and to evaluate the translational relevance of these effects for human female reproductive health.