Melatonin rescues cardiovascular dysfunction during hypoxic development in the chick embryo.

Area of Science:

• Cardiovascular Biology
• Developmental Biology
• Perinatal Medicine

Background:

• Chronic fetal hypoxia during pregnancy can lead to fetal growth restriction (FGR) and cardiovascular disease.
• Melatonin is known to protect the placenta in adverse pregnancies, but its direct effects on the fetal cardiovascular system are unclear.
• The potential for melatonin to rescue established fetal cardiovascular dysfunction following FGR diagnosis requires investigation.

Purpose of the Study:

• To investigate whether melatonin directly protects the fetal cardiovascular system from hypoxic injury.
• To determine if melatonin can rescue fetal cardiovascular dysfunction when administered after the diagnosis of fetal growth restriction (FGR).

Main Methods:

• Chick embryos were exposed to normoxia or hypoxia (14% O2) from day 1 of incubation.
• Melatonin treatment (1 mg/kg/day) was administered from day 13 of incubation (term ~21 days).
• Cardiac function, vascular function, and underlying molecular mechanisms were assessed.

Main Results:

• Melatonin treatment in hypoxic chick embryos rescued cardiac systolic dysfunction, impaired contractility, and endothelial dysfunction.
• It also normalized increased cardiac sympathetic dominance.
• Mechanisms included reduced oxidative stress, enhanced antioxidant capacity, restored vascular endothelial growth factor expression, and improved NO bioavailability.

Conclusions:

• Melatonin administered during late-stage hypoxic development rescues early-onset cardiovascular dysfunction.
• Melatonin treatment initiated after fetal growth restriction diagnosis can protect the fetal cardiovascular system.
• Melatonin is a potential antioxidant therapy for protecting the fetal cardiovascular system in adverse pregnancies.