Study of the effect of sodium butyrate on short-chain fatty acid receptors in the enteric nervous system of mice after experimental Ulcerative Colitis

• Grant number: 22/00086-1
• Support Opportunities: Regular Research Grants
• Start date: July 01, 2023
• End date: June 30, 2026
• Field of knowledge: Biological Sciences - Morphology - Anatomy
• Principal Investigator: Patricia Castelucci
• Grantee: Patricia Castelucci
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Intestinal inflammation affects enteric neurons. Butyrate is a short-chain fatty acid produced by bacteria in the intestinal microbiota from the fermentation of dietary fibers. It binds to G protein-coupled fatty acid receptors, such as GPR41, GPR43 and GPR109, and contributes to the maintenance of the intestinal barrier, protection against pathogens and, as an anti-inflammatory. The presence of short-chain fatty acid receptors in the enteric nervous system has been observed. The literature demonstrates that sodium butyrate has been promising in the treatment of ulcerative colitis due to its anti-inflammatory and neuromodulatory effects. Therefore, this project aims to study the GPR41, GPR43 and GPR109 receptors and analyze the effect of the use of sodium butyrate on myenteric plexus neurons of mice submitted to experimental ulcerative colitis. For this, the 2, 4, 6, trinitrobenzene sulfonic acid (TNBS) will be injected in the large intestine of C57BL/6 animals and the Sham group will be injected with the vehicle (alcohol). The animals submitted to experimental ulcerative colitis will be treated with Sodium Butyrate, via gavage, and the Sham group will receive an equivalent volume of saline. The animals will be euthanized 7 and 14 days after TNBS or vehicle injection and Sodium Butyrate treatment. The following will be analyzed: A) The colocalization of GPR41, GPR43 and GPR109 receptors with neurons immunoreactive to neuronal nitric oxide synthase (nNOS), Acetylcholine Transferase (ChAT), Calretin (Carl), PGP9.5 (pan neuron) and with the pan marker -glial GFAP; B) Neurons/ganglia positive to GPR41, GPR43 and GPR109 receptors, to nNOS, ChAT, Calr, PGP9.5 and to glial fibrillary acidic protein (GFAP) immunoreactive glial cells; C) The areas of the profiles of neurons immunoreactive to nNOS, ChAT, Calr, PGP9.5; D) The morphology of the distal colon using the histology technique, using Hematoxylin & Eosin, Periodic Acid Schiff (PAS) and Picrosirius Red staining; E) intestinal motility; F) protein expression and gene expression of caspase-3, of NF-º², of histone deacetylase, of MAPKinases; G) Analysis of the intestinal microbiota; H) Analysis of GPR41, GPR43 and GPR109 receptors in patients with Ulcerative Colitis or Crohn's Disease and I) study of cell culture of myenteric neurons and In vitro. The results will be expressed as mean ± standard error and statistical analysis will be performed. (AU)