MT1/cAMP/PKA Pathway in Melatonin-Regulated Sperm Capacitation

Area of Science:

• Reproductive Biology
• Endocrinology
• Molecular Biology

Background:

• Melatonin, a hormone primarily from the pineal gland, influences reproductive functions.
• Sperm capacitation is essential for fertilization, but melatonin's role in this process in mice is not fully understood.

Purpose of the Study:

• To investigate the effects of melatonin on mouse sperm capacitation.
• To elucidate the underlying molecular mechanisms of melatonin-mediated sperm capacitation.

Main Methods:

• Mouse sperm from the cauda epididymis were cultured with varying melatonin concentrations.
• Sperm capacitation markers, including tyrosine phosphorylation and intracellular calcium, were assessed.
• Fertilizing capacity was evaluated in vitro (oocyte cleavage) and in vivo (fetus development).

Main Results:

• 10^-7 mol/L melatonin significantly enhanced sperm capacitation, increasing tyrosine phosphorylation, capacitated sperm percentage, and intracellular calcium.
• Melatonin improved fertilizing capacity, evidenced by higher oocyte cleavage rates and increased fetal numbers in mated females.
• The MT1/cyclic adenosine monophosphate (cAMP)/p-Protein kinase A (p-PKA) pathway was identified as the key mechanism.

Conclusions:

• Melatonin promotes mouse sperm capacitation and enhances fertilizing capacity through the MT1/cAMP/p-PKA signaling pathway.
• These findings provide critical insights into the molecular regulation of sperm capacitation by melatonin.
• The study offers theoretical support for controlling sperm capacitation in assisted reproductive technologies like artificial insemination.