Vitamin D receptor expression in sperm of males with unexplained infertility.

Background: Vitamin D is associated with numerous disorders, including infertility. Accordingly, the goal of this research was to find out the level of vitamin D and messenger RNA (mRNA) expression of vitamin D receptor (VDR) in the sperm of male subjects with unexplained infertility.

Methods: Twenty-four unexplained infertile men as the case group and 22 healthy fertile men as the control group were recruited. Vitamin D levels were evaluated in seminal fluid using enzyme-linked immunosorbent assay (ELISA). Afterwards, the swim-up test was performed to isolate motile sperm cells. From these cells, RNA was extracted, complementary DNA (cDNA) was synthesized, and mRNA expression of the VDR gene was evaluated with quantitative real-time polymerase chain reaction (PCR).

Results: A decrease in VDR mRNA expression levels was detected in the case group compared to the control group, but this reduction was not statistically significant (p>0.05). Besides, the level of vitamin D in seminal fluid was not detectable in both groups.

Conclusion: The sperm of unexplained infertile men express VDR gene mRNA, although there was no vitamin D in seminal samples. Hence, vitamin D and VDR signaling might not be effective in the etiopathogenesis of unexplained infertility in men.