Does Rheumatoid Arthritis Affects the Nitrergic Density and Somatic Area of the nNOS-Immunoreactive (IR) Myenteric Neurons, as well as the Morphometric Areas of CGRP and VIP-IR Varicosities of the Ileum of Arthritic Rats?

Abstract

Few studies regarding arthritic diseases have been performed to verify the presence of the neurodegeneration. Given the increased oxidative stress and extra-articular effects of the rheumatoid arthritis, the gastrointestinal studies should be further investigated aiming a better understanding of the systemic effects the disease on enteric nervous system. To determine whether the rheumatoid arthritis affects the nitrergic density and somatic area of the nNOSimmunoreactive (IR) myenteric neurons, as well as the morphometric areas of CGRP and VIP-IR varicosities of the ileum of arthritic rats. Twenty 58-day-old male Holtzmann rats were distributed in two groups: control and arthritic. The arthritic group received a single injection of the Freund's Complete Adjuvant in order to induce arthritis model. The whole-mount preparations of ileum were processed for immunohistochemistry to VIP, CGRP and nNOS. Quantification was used for the nitrergic neurons and morphometric analyses were performed for the three markers. The arthritic disease induced a reduction 6% in ileal area compared to control group. No significant differences were observed in nitrergic density comparing both groups. However, arthritic group yielded a reduction of the nitrergic neuronal somatic area and VIP-IR varicosity areas. However, an increase of varicosity CGRP-IR areas was also observed. Despite arthritis resulted in no alterations in the number of nitrergic neurons, the retraction of ileal area and reduction of nitrergic somatic and VIP-IR varicosity areas may suggest a negative impact the disease on the ENS.