The distribution and co-localization of immunoreactivity to nitric oxide synthase, vasoactive intestinal polypeptide and substance P within nerve fibres supplying bovine and porcine female genital organs

Abstract

The distribution of nitric oxide synthase-immunoreactive (NOS-IR) axons and their relationship to structures immunoreactive to vasoactive intestinal polypeptide (VIP), substance P (SP) and tyrosine hydroxylase (TH) were studied by means of the nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) technique or double-labelling immunofluorescence in the genital organs of cow and pig. Relevant neurons were also investigated in the pig. NOS-containing neural structures were TH-immunonegative in bovine or porcine genital organs, or in the studied ganglia. In the bovine ovary, NOS-IR nerves were neither VIP-IR nor SP-IR, whereas in the pig, most NOS-containing axons were also VIP-IR. The oviduct was supplied by single NOS/VIP- or NOS/SP-containing nerves, whereas in the uterus, NOS-IR axons were moderate in number, often being immunoreactive for VIP or SP. Numerous NOS/VIP-IR and NOS/SP-IR nerves were found in the vagina of both species. In all tissues studied, NOS-IR axons were mainly related to vascular smooth muscle. Most of the neurons of the paracervical ganglia and some neurons in dorsal root ganglia exhibited strong NOS activity. Only single neurons in sympathetic ganglia were NADPH-d-positive. Most nitrergic neurons in the autonomic ganglia were VIP-IR but SP-immunonegative. The sensory neurons were mostly NOS/SP-IR, whereas only single neurons co-expressed NOS and VIP immunoreactivity.

Sensory and Autonomic Neurons Project Both to the Smooth Retractor Penis and to the Striated Bulbospongiosus Muscles. Neurochemical Features of the Sympathetic Subset

“…As noradrenergic fibers are usually found in the muscular coat or around blood vessels of genital organs (Kaleczyc et al, 1993;Majewski et al, 1995;Czaja et al, 1996;Anderson and Stief, 1997), we think that the TH-or DbH-IR RDL neurons exert contemporaneously their influence on the smooth muscular cells and on the blood vessels of the smooth RPM and of the striated BSM.…”

“…These NPY-positive neurons certainly play a fundamental role in blood flow regulation (Gibbins, 1991), in fact NPY is a potent vasoconstrictor of many mammalian blood arteries (McLachlan and Llewellyn-Smith, 1986;Morris and Gibbins, 1987;Lindh et al, 1989;Lundberg et al, 1990;Majewski et al, 1995). Moreover, in the female NPY regulates also the contractile activity of nonvascular smooth muscle cells of the uterus and oviduct, as well as the secretory function of the ovary (Markiewicz et al, 2003).…”

“…VIP-ergic neurons play a role in blood flow regulation, because, like NO, VIP acts as vasodilator on genital organ blood vessels (Polak et al, 1981;Morris et al, 1985;Majewski et al, 1995) and displays a physiological antagonism with NPY in the control of blood flow (Morris et al, 1985). VIP also plays a relaxatory role in the muscular wall of the genital tract (Lynch et al, 1980;Owman and Stjernquist, 1988;Palle et al, 1989).…”

“…This peptide is commonly considered a marker of afferent pathways (Majewski et al, 1995;Kaleczyc et al, 1997;Czaja, 2000), therefore, its presence within sympathetic neurons is an unforeseen finding. However, CGRP has been also shown in the STG neurons of the boar (Hill and Elde, 1989;H€ app€ ol€ a et al, 1993;Lakomy et al, 1994), sow (Panu et al, 2001;Ragionieri et al, 2008) cat (Kummer and Heym, 1988;Lindh et al, 1989) and horse (Nasu et al, 2003).…”

“…However, like CGRP, SP is a tachykinin commonly considered a marker of afferent pathways, so its putative physiological significance might be that it play a role in some visceral reflexes and neuroendocrine responses (Traurig et al, 1991;Majewski et al, 1995).…”