Circadian System and Melatonin Hormone: Risk Factors for Complications during Pregnancy

Area of Science:

• Reproductive biology
• Chronobiology
• Placental physiology

Background:

• Pregnancy involves complex, timed events; circadian rhythm disruptions (e.g., shiftwork) are linked to adverse outcomes like preterm birth and preeclampsia.
• Emerging evidence suggests the placenta has a functional circadian system, expressing key clock genes (Bmal1, Per1-2, Clock).
• The human placenta synthesizes melatonin, a hormone crucial for circadian regulation in other tissues, though its local role and pattern remain unclear.

Purpose of the Study:

• To review current knowledge on placental clock genes and their regulation.
• To explore the synthesis and function of melatonin within the human placenta.
• To analyze the interplay between placental circadian mechanisms, melatonin, and genes like VEGF.

Main Methods:

• Literature review of studies on placental clock genes.
• Analysis of research on placental melatonin synthesis and its potential circadian patterns.
• Examination of the effects of melatonin on placental gene expression, including antioxidant enzymes and VEGF.

Main Results:

• The placenta expresses core clock genes, suggesting an intrinsic circadian system.
• Melatonin is synthesized in the placenta and influences antioxidant enzymes (catalase, superoxide dismutase) and VEGF expression.
• Melatonin's local production may protect against oxidative stress and modulate VEGF, a gene potentially controlled by clock genes.

Conclusions:

• The placenta exhibits molecular clock components and synthesizes melatonin.
• Placental melatonin plays a role in regulating antioxidant defenses and VEGF, potentially influenced by circadian mechanisms.
• Further research is needed to elucidate the precise role and regulation of placental melatonin synthesis and its impact on pregnancy health.