Melatonin in testes of infertile men: evidence for anti-proliferative and anti-oxidant effects on local macrophage and mast cell populations.
Level 5 - mechanism / opinion, no new human data
Laboratory bench research combining human tissue biopsies with in vitro cell cultures.
PubMed 24659586 · doi:10.1111/j.2047-2927.2014.00207.x
What was done
The authors investigated testicular targets of melatonin and its local effects on proliferation, inflammation, and oxidative stress. They analyzed human testicular biopsies from patients with idiopathic infertility (hypospermatogenesis or Sertoli cell-only syndrome) and conducted in vitro experiments using human macrophage cell lines (THP-1), primary hamster testicular macrophages, and a human mast cell line (HMC-1). They evaluated melatonergic receptor presence, cytokine and enzyme expression, cell proliferation, and reactive oxygen species (ROS) levels.
What was found
Melatonergic receptors were identified on human testicular macrophages (MACs) and mast cells (MCs). In testicular biopsies, melatonin concentrations correlated negatively with MAC density (per mm²) and expression of TNF-α, IL-1β, and COX-2, but positively correlated with expression of antioxidant enzymes (SOD1, peroxiredoxin 1, catalase; exact numerical values not reported). In THP-1 and primary hamster testicular MACs, melatonin inhibited cell proliferation and reduced pro-inflammatory cytokines and COX-2 expression. In HMC-1 mast cells, melatonin upregulated antioxidant enzymes and decreased ROS generation.
Why it matters
This study demonstrates that melatonin acts directly on testicular macrophages and mast cells in infertile men, highlighting local anti-inflammatory and antioxidant pathways within the human testis.
Limits
The abstract reports no sample sizes, correlation coefficients, or numerical values for the human biopsy data. Much of the functional evidence derives from in vitro cell lines and animal models, which may not replicate in vivo human testicular physiology or predict clinical reproductive outcomes.
Cited by
- supports T lymphocytes, natural killer cells, and mast cells express melatonin receptors.