IMPACT OF EXOGENOUS THYROXINE ON BRAIN DEVELOPMENT IN OFFSPRING OF RATS WITH GESTATIONAL HYPERTENSION: IMPLICATIONS FOR EARLY ATHLETIC TRAINING AND DEVELOPMENT

Abstract

Objective: This study examines the impact of gestational hypertension on offspring brain development in rats and assesses the potential mitigating effects of exogenous thyroxine on these outcomes. Methods: Thirty-six female Sprague-Dawley rats were assigned to three groups: a normal control group (N), a gestational hypertension-induced brain injury group (PIH), and a hypertension group treated with thyroxine (PIH+T). Gestational hypertension was induced in the PIH and PIH+T groups from gestational day 14 until delivery. Post-birth, thyroxine (5.0μg/kg) was administered subcutaneously to the PIH+T group from day 1 to day 10, while the PIH and N groups received saline. Measurements taken included maternal blood pressure, blood thyroxine levels, offspring body weight, and brain development indicators such as the morphology and distribution of BDNF-positive neurons and BDNF protein levels, assessed through immunohistochemistry and ELISA. Results: The systolic blood pressure of pregnant rats in the PIH group was significantly higher than in the N group pre-delivery. Correspondingly, thyroxine levels were lower in the PIH group compared to the N group. Offspring from the PIH group showed significantly lower body weights from birth to day 21 compared to the N and PIH+T groups, with a reversal by day 28. The thyroxine-treated PIH+T group demonstrated enhanced BDNF-positive neuronal development from day 7, similar to the normal group, indicating improved brain development. BDNF protein levels were initially lower in the PIH and PIH+T groups but normalized in the PIH+T group by day 7. Conclusions: Exogenous thyroxine administration in neonatal rats born to mothers with gestational hypertension significantly ameliorates the detrimental effects of maternal hypertension on brain development. By enhancing BDNF synthesis in the cerebral cortex, thyroxine treatment supports normal brain development, potentially offsetting the negative impacts of prenatal stressors. These findings underscore the importance of early thyroid hormone intervention in improving developmental outcomes, which may have long-term benefits in enhancing the neurological foundation necessary for athletic training and physical performance in later life.