Paper Title
The Influence of Bisphenol a (BPA) on the Neurochemical Characteristic of Intramural Neurons of the Porcine Urinary Bladder Trigone

Abstract
Bisphenol A (BPA) is a substance commonly used in the production of plastic and it is one of the most widespread toxins in the environment. BPA is a component of a wide range of everyday objects includingbottles, food containers and cans. First of all BPA affects the nervous and reproductive systems. A high exposition to BPA results in disorders in the development of dendrites, axons and synapses, as well as changes in the sensory stimuli conduction. In turn, within the reproductive system BPA causes changes in the uterine mucosal layer, cells apoptosis and expression of the estrogen receptors. The aim of this study was to determine for the first time the influence of low doses of BPA on the nervous structures localized in the wall of the urinary bladder trigone of the domestic pig. Pigs were divided into two groups (five animals in each group): control animals received empty capsules for 28 days and experimental animals received capsules with BPA in doses 0,05 mg/kg body weight/day. After this period all animals were euthanized. The fragments of the wall of urinary bladder trigone were subjected to routine double immunofluorescence method using antisera against protein gene-product 9.5 (PGP 9.5, used here as a pan-neuronal marker), substance P (SP), galanin (GAL), vasoactive intestinal polypeptide (VIP), neuronal isoform of nitric oxide synthase (nNOS) and cocaine- and amphetamine-regulated transcript peptide (CART). It was found that BPA affect the neurochemical characteristic of the nervous structures in the wall of the urinary bladder trigone. Changes consisted in the increase in the percentage of neurons immunoreactive to all substances studied, and the most visible fluctuations related to cells immunoreactive to VIP (increase from 32,22±0,57% to 42,68±0,86%) and/or GAL (increase from 26,16±0,74% to 35,29±1,16%). The increase was also observed in the case of nNOS-positive neurons (from 43,72% to 47,49%) and CART-immunoreactive cells (from 38,65% to 44,95%). The slightest changes related to SP – positive neurons (increase from 20.70 ±0,82% to 23,86±0,40%). Moreover, it was found that low doses of BPA affect the neurochemical coding of nerve fibers in the wall of the urinary bladder. The obtained results show that even low doses of BPA (considered to be safe) are not neutral for the living organisms and clearly change the neurochemical characteristic of the nervous structures located the wall of the urinary bladder trigone of the domestic pig, and the observed changes may be the first, subclinical sign of BPA intoxication. Similarities in neurochemical organization of the nervous system between humans and pigs suggest that similar mechanisms may be observed in the human urinary bladder. The experiment supported by KNOW (Leading National Research Centre) Scientific Consortium "Healthy Animal - Safe Food", decision of Ministry of Science and Higher Education No. 05-1/KNOW2/2015.