Long-term Estradiol-17.BETA. Administration Decreases the Number of Neurons in the Caudal Mesenteric Ganglion Innervating the Ovary in Sexually Mature Gilts

Abstract

Abstract. The effect of estradiol-17β (E2) on the number and distribution of neurons in the caudal mesenteric ganglion (CaMG) supplying the ovary of adult pigs was investigated. Also, the numbers of ovarian dopamine-β-hydroxylase (Dβ H -), neuropeptide Y (NPY-), somatostatin (SOM-), galanin (GAL-) and estrogen receptor (ER)-immunoreactive perikarya as well as the density of the intraganglionic nerve fibers containing Dβ H and/or NPY, SOM, GAL were determined. E2 was administered i.m. from day 4 of the first studied estrous cycle to the expected day 20 of the second studied cycle. Injections of E2 (1) increased the E2 level in the peripheral blood approximately 4-5 fold, (2) decreased the number of small-sized Fast Blue-positive postganglionic neurons in the CaMG, (3) decreased the number of small perikarya in the ventral, dorsal and central regions of the CaMG, (4) decreased the number of large perikarya in the dorsal and central regions, (5) [6]. Virtually all ovary-projecting postganglionic CaMG neurons in immature and adult pigs are noradrenergic; that is, they express enzymes participating in the synthesis of noradrenaline-tyrosine hydroxylase (TH) and dopamine-β-hydroxylase (Dβ H) [3,4]. Moreover, sympathetic perikarya and nerve fibers within this ganglion have also been found to be immunoreactive to other active substances in a number of mammals, including adult cats [7], immature rats [8], fetal and adult guinea-pigs [9] and prepubertal pigs [3,4]. The reactive substances include neuropeptide Y (NPY), somatostatin (SOM), galanin (GAL), calcitonin gene-related peptide (CGRP), cholecystokinin, bombesin/gastrin-releasing peptide, substance P (SP), vasoactive intestinal polypeptide (VIP), opioid peptides and enkephalins. The abundance of bioactive substances expressed in postganglionic sympathetic CaMG perikarya innervating the ovary correlates with a variety of the ovarian sympathetic actions including regulation of steroidogenesis, blood supply as well as development and ovulation of follicles (as reviewed by Kotwica et al. [10] and Jana et al.[11]).In rats, a close relationship was found between estrogens and sympathetic and sensory neurons supplying the genitourinary system. Estrogen receptor (ER) subtypes α and β are localized in preand paravertebral (at thoracolumbar neuromeres) sympathetic neurons projecting to the ovary and uterus [12,13] and proximal urethra [14]. The number of celiac ganglion neurons innervating the rat ovary and the content of ERs in these cells decreased after prenatal diethylstilbestrol exposure [15]. In turn, prepubertal β-estradiol-17-cypionate treatment increased the neuronal size in the rat celiac ganglion [12]. In female rats, DRG sensory neurons in L6-S1 segments that innervate the uterus [16,17] and urinary bladder [18] also express ER subtypes α and β. In rats, an increase in the content of ERα in L6-S1 DRG neurons projecting to the uterine cervix near term is thought to occur in parallel with augmentation of plasma estrogens. The expressions of ERs, SP [19], CGRP [20] a...

Reduction of the Number of Neurones in the Caudal Mesenteric Ganglion Innervating the Ovary in Sexually Mature Gilts Following Testosterone Administration

“…). Almost all gonad‐projecting postganglionic CaMG neurones in immature and adult pigs are noradrenergic [i.e. express enzymes participating in the synthesis of noradrenaline (NA), tyrosine hydroxylase (TH) and dopamine‐β‐hydroxylase (DβH)].…”

“…express enzymes participating in the synthesis of noradrenaline (NA), tyrosine hydroxylase (TH) and dopamine‐β‐hydroxylase (DβH)]. Besides NA, sympathetic perikarya within this ganglion in laboratory animals , as well as in prepubertal and adult pigs, were also found to express other active substances, such as neuropeptide Y (NPY), somatostatin (SOM), galanin (GAL), calcitonin gene‐related peptide (CGRP), cholecystokinin, bombesin/gastrin‐releasing peptide, substance P, vasoactive intestinal polypeptide (VIP), opioid peptides and enkephalins. The above‐mentioned neurotransmitters were also exhibited in the nerve fibres within the porcine CaMG .…”

Localization of substance P, calcitonin gene related peptide and galanin in the nerve fibers of porcine cystic ovaries

“…Exogenous estrogens administration reduced the number of ERs-containing ovarian neurons in the rat celiac ganglion [38]. Also, long-term estrogen treatment led to a decrease in the number of both noradrenergic and ERs-expressing ovarian neurons in the caudal mesenteric ganglion of adult gilts [39]. It is worth noting that in the gilts from which cystic ovaries were collected for the present study, the levels of estrogens and androstendione increased in the peripheral blood (unpublished data), and the intraovarian expression of steroidogenic enzymes also changed [26].…”

Changes in the Cholinergic Innervation Pattern of Porcine Ovaries with Cysts Induced by Dexamethasone Administration

“…On the other hand, the changed chemical coding of neurons may be a result of the direct effects of steroid hormones on these cells as well. It is recognized that estrogen receptors are expressed in the ovarian neurons of sympathetic and parasympathetic as well as sensory ganglia in adult gilts and that the long-term 17β-estradiol treatment reduced the population of these neurons (Koszykowska et al 2011a, b; Jana et al 2012, 2013a). A similar situation has been revealed for neurons in the caudal mesenteric ganglion innervating the ovary in adult gilts following testosterone administration (Jana et al 2013b).…”