Leptin and leptin receptor in human seminal plasma and in human spermatozoa

Abstract

Leptin, a 167 amino acid peptide, is known to influence the gonads via direct and indirect effects. Recent studies provide contradictory proposition about the peripheral impact of leptin in the male gonads. Thus, we examined leptin and its receptors in human seminal plasma and in human ejaculated spermatozoa by Western blot technique and fluorescence microscopy. In seminal plasma we found a free leptin band (16 kDa) by an anti-leptin polyclonal antibody. Incubation of seminal plasma with recombinant leptin caused a statistically significant increase in the amount of free leptin (p < 0.01) and supports this finding. Furthermore, a soluble leptin receptor (145 kDa) was found in human seminal plasma in the same specimen. We also detected a 145-kDa leptin receptor isoform in ejaculated spermatozoa as a possible target of leptin action in the male genital tract, which was localized at the tail of spermatozoa by immunofluorescence microscopy only. This receptor was significantly associated with the intactness of sperm plasma membranes. Spermatozoa with deteriorated membranes contained 49.2 +/- 6.9% leptin receptor signal intensity compared with spermatozoa having intact membranes (p < 0.01). This finding is difficult to interpret and may be caused by a leakage of OB-R due to loss of membrane integrity. In conclusion, these data provide further hints for a peripheral role of leptin in the male genital tract, possibly, by an interaction between leptin and spermatozoa via sperm leptin receptors.

Semen parameters and hormonal profile in obese fertile and infertile males

“…Jope et al (6) illustrated the presence of a leptin receptor on intact sperm plasma membrane, suggesting that it might have an impact on the gonadal function indirectly by the central neuroendocrine system and directly through the peripheral tissue membrane receptors. Ishikawa et al (24) showed that spermatogenic dysfunction is associated with increased leptin and leptin receptor expression in the testis.…”

Leptin Receptor in Ram Epididymal Spermatozoa

“…However new findings suggest that some of these transcripts can code for proteins essential in early embryo development [10]. Moreover, recent studies have shown that mRNA of leptin receptor is in human, swine and bovine spermatozoa [14,16,17]. However, to our knowledge, this is the first time that the presence of mRNA of Ob-R and Ob-Rb in ram epididymal spermatozoa has been demonstrated.…”

Leptin and Leptin Receptor are Expressed only in Clear Cells of Rat Epididymis Epithelia

“…Because both epididymis regions express leptin and OBR at gene and protein levels, we could assume that this hormone may have a potential action on this organ in both spermatozoa and epithelial membrane. As leptin role on spermatozoa is still contradictory (Jope et al, 2003;Li, Chiu et al, 2009;LangeConsiglio et al, 2014) and we do not have enough information about its role on epididymis, further studies are necessary to establish in which epididymis functions leptin are involved.…”