Localization of 5‐hydroxytryptamine‐like immunoreactive cells and nerve fibers in the rat female reproductive system

Abstract

The presence of 5-hydroxytryptamine (5-HT)-like immunoreactivity (IR) was studied in the rat female reproductive system using polyclonal antibodies directed against 5-HT. Moreover, 5-HT levels in the ovary, oviduct, uterus, and cervix were measured by high-pressure liquid chromatography with electrochemical detection. The highest 5-HT concentrations were found in the oviduct, followed in descending order by the cervix, the ovary, and the uterus. Most 5-HT-like IR was observed in the cytoplasm of mast cells. These cells were found in the connective tissue around the fimbria, in the oviduct, in the uterus, and in the ovary. Mast cells are clustered in the proximity of the parenchymal blood vessels. Moreover, a few 5-HT-like nerve fibers were found distributed mainly perivascularily in the uterine cervix and in the uterine horns as well as in the oviduct. IR nerve fibers were rarely seen within the ovary. The present data provide direct evidence that 5-HT in the female reproductive system not only is associated with mast cells but is located in nerve fibre-like structures as well. The functional significance of this probable 5-HT-ergic innervation of the female reproductive tract discovered in the present study should be clarified in future investigations.

Evidence of 5-HT components in human sperm: implications for protein tyrosine phosphorylation and the physiology of motility

“…Taken together, the current findings support an important role of 5-HT on the migration of sperm throughout the female tract. The possibility that 5-HT plays a role in sperm physiology may occur at 5-HT receptors and/or 5-HT transporters located on the surface of sperm, responding to the 5-HT contained in the uterine or seminal fluid (Mann et al 1961, Amenta et al 1992. However, the surprising finding that some other serotoninergic elements are intracellular remains unclear and requires further investigation.…”

Serotonin in pre-implantation mouse embryos is localized to the mitochondria and can modulate mitochondrial potential

“…This PCR-based assay could also detect a minimum of 10 femtograms. These results indicate that serotonin present in embryos could arise either through synthesis by TPH2 or by transport from extracellular sources, for example, serotonin present in the tubal fluid of the oviduct (Juorio et al 1989, Amenta et al 1992, Yavarone et al 1993. The multiplicity of the mechanisms for obtaining serotonin may indicate the importance of this molecule to the embryo.…”

“…In mammals, such studies have been lacking, though in mice, drastic effects are observed in the early embryo upon blocking tryptophan hydroxylase, the rate-limiting enzyme in serotonin synthesis. Serotonin is present in the tubal fluid of the oviduct, cervix, and uterus (Juorio et al 1989, Amenta et al 1992, Yavarone et al 1993). On administering p-chlorophenylalanine, a tryptophan hydroxylase inhibitor, to pregnant mice, it was observed that the cleavage divisions of the zygote were arrested and in cases where the embryo proceeded to the blastocyst stage, it was defective and failed to implant (Khozhai et al 1995).…”

Intracellular cAMP and Calcium Signaling by Serotonin in Mouse Cumulus-Oocyte Complexes

“…Among the indications that 5-HT might be such a local regulator is its detection in female rodent genital tracts (Amenta et al, 1992) and in human follicular fluid (Bodis et al, 1993). Moreover, 5-HT has also been reported recently in isolated mouse oocytes and embryos (Il'kova et al, 2004;Amireault and Dubé, 2005) and in surrounding cumulus cells that also possess the rate-limiting enzyme tryptophan hydroxylase for 5-HT production, thus making these cells a potential immediate direct source of 5-HT (Amireault and Dubé, 2005).…”