# Prenatal Melatonin Modulates Cardiovascular Function and Oxidative Stress in Guinea Pig Neonates Under Normoxic and Hypoxic Gestation

## TL;DR

Prenatal melatonin helps reduce heart and blood vessel issues in guinea pig babies born to mothers exposed to low oxygen, but it may also cause unexpected changes in normal pregnancies.

## Contribution

This study shows prenatal melatonin can mitigate hypoxia-induced cardiovascular and oxidative stress effects in guinea pig neonates.

## Key findings

- Melatonin reversed hypoxia-induced endothelial dysfunction and oxidative stress in neonates.
- Melatonin increased catalase activity in hypoxic neonates, improving redox balance.
- Melatonin altered cardiac structure in normoxic pregnancies, increasing LV length and decreasing nuclei density.

## Abstract

Introduction: Gestational hypoxia (GH) increases the risk of cardiovascular diseases by inducing oxidative stress and vascular dysfunction. This study investigates whether prenatal melatonin can mitigate these effects in guinea pigs. Methods: Pregnant guinea pigs were exposed to normoxia or hypoxia and treated with melatonin (1 mg/kg/day). Echocardiography, vascular reactivity, and molecular assays were used to assess cardiovascular structure, function, and redox balance in neonates. Results: GH reduced neonatal birth weight and altered left ventricular (LV) development, resulting in increased LV systolic function and aortic blood flow velocity. Melatonin treatment reversed these effects, restoring endothelial-dependent vasodilation and decreasing oxidative stress in the LV and thoracic aorta. Catalase antioxidant enzyme activity was elevated in melatonin-treated hypoxic neonates. Unexpectedly, melatonin treatment altered cardiac structure in normoxic pregnancies, increasing LV length and decreasing LV myocardial nuclei density. Conclusions: Prenatal melatonin partially modulates GH-induced endothelial dysfunction and oxidative stress, offering potential therapeutic value. However, its effects under normoxic conditions deserve caution, emphasizing the need for targeted use only in pregnancies with evident hypoxic and oxidative stress conditions.