Inhibitory effect of melatonin on testosterone synthesis is mediated via GATA-4/SF-1 transcription factors

Area of Science:

• Reproductive Endocrinology
• Molecular Endocrinology
• Chronobiology

Background:

• Melatonin, a hormone regulating circadian rhythms, influences various physiological processes.
• Its role in modulating testosterone production is not fully understood.
• The GATA-4/SF-1 signaling pathway is critical for steroidogenesis.

Purpose of the Study:

• To investigate the involvement of the GATA-4/SF-1 pathway in melatonin's inhibitory effects on testosterone production.
• To examine these effects in both an in vitro Leydig cell line and in vivo mouse models.

Main Methods:

• In vitro studies using TM3 Leydig cells treated with melatonin.
• In vivo studies involving intratesticular injections of melatonin in C57BL/6J mice.
• Analysis of testosterone levels, cyclic adenosine monophosphate (cAMP) accumulation, and mRNA/protein expression of key steroidogenic genes and transcription factors (GATA-4, SF-1, StAR, P450SCC, 3β-HSD).
• Use of N-acetyl-2-benzyltryptamin, a melatonin receptor antagonist, to confirm pathway specificity.

Main Results:

• Melatonin significantly reduced testosterone levels and cAMP accumulation in Leydig cells.
• Melatonin decreased the expression of GATA-4, SF-1, StAR, P450SCC, and 3β-HSD mRNA and protein.
• These inhibitory effects were reversed by the melatonin receptor antagonist.
• Similar down-regulation of testosterone production, GATA-4, and SF-1 was observed in mice treated with melatonin.

Conclusions:

• The GATA-4/SF-1 signaling pathway mediates the inhibitory effects of melatonin on testosterone production.
• Melatonin exerts its inhibitory action by down-regulating the expression of GATA-4 and SF-1.
• These findings provide insights into the molecular mechanisms underlying melatonin's impact on male reproductive function.