Analysis of the Expression of Tachykinins and Tachykinin Receptors in the Rat Uterus During Early Pregnancy.

The peptides of the tachykinin family participate in the regulation of reproductive function acting at both central and peripheral levels. Our previous data showed that treatment of rats with a tachykinin NK3R antagonist caused a reduction of litter size. In the present study, we analyzed the expression of tachykinins and tachykinin receptors in the rat uterus during early pregnancy. Uterine samples were obtained from early pregnant rats (Days 1-9 of pregnancy) and from nonpregnant rats during the proestrus stage of the ovarian cycle, and real-time quantitative RT-PCR, immunohistochemistry, and Western blot studies were used to investigate the pattern of expression of tachykinins and tachykinin receptors. We found that all tachykinins and tachykinin receptors were locally synthesized in the uterus of early pregnant rats. The expression of substance P, neurokinin B, and the tachykinin receptors NK1R and NK3R mRNAs and proteins underwent major changes during the days around implantation and they were widely distributed in implantation sites, being particularly abundant in decidual cells. These findings support the involvement of the tachykinin system in the series of uterine events that occur around embryo implantation in the rat.

Molecular and functional characterization of voltage-gated sodium channels in human sperm.

BACKGROUND: We have investigated the expression of voltage-gated sodium channels in human spermatozoa and characterized their role in sperm motility. METHODS: Freshly ejaculated semen was collected from thirty normozoospermic human donors, with each donor supplying 2 different samples. Reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence techniques were used to detect the mRNAs and proteins of interest. Sperm motility was measured by a computer-assisted sperm analysis system (CASA). Cytosolic free calcium was determined by fluorimetry in cells loaded with the fluorescent calcium indicator Fura-2. RESULTS: The mRNAs that encode the different Nav alpha subunits (Nav1.1-1.9) were all expressed in capacitated human spermatozoa. The mRNAs of the auxiliary subunits beta1, beta3 and beta4 were also present. Immunofluorescence studies showed that, with the exception of Nav1.1 and Nav1.3, the Nav channel proteins were present in sperm cells and show specific and different sites of localization. Veratridine, a voltage-gated sodium channel activator, caused time- and concentration-dependent increases in progressive sperm motility. In sperm suspensions loaded with Fura-2, veratridine did not modify intracellular free calcium levels. CONCLUSION: This research shows the presence of voltage-gated sodium channels in human sperm and supports a role for these channels in the regulation of mature sperm function.