Influence of the P2X7 Purinergic Receptor on the Enteric Nervous System of Female Knockout Mice Induced by Experimental Ulcerative Colitis

• Grant number: 24/20750-9
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: August 01, 2025
• End date: July 31, 2028
• Field of knowledge: Biological Sciences - Morphology - Anatomy
• Principal Investigator: Patricia Castelucci
• Grantee: Lucas Casagrande
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Ulcerative colitis (UC) compromises the enteric nervous system (ENS), affecting intestinal motility. The purinergic P2X7 receptor is involved in inflammatory and apoptotic pathways during UC. Female sex hormones, such as estrogen, can modulate these inflammatory responses, primarily through estrogen receptors ER¿ and ER¿. This study aims to investigate the effects of P2X7 receptor deficiency in the ENS of female knockout (KO) mice with experimental colitis, focusing on enteric neurotransmission and the effects of estrogen. A total of 56 female C57BL/6 mice will be used, divided into seven experimental groups with 8 animals each: wild-type control (WT control), wild-type ovariectomized (WT OVX), wild-type colitis (WT OVX colitis), knockout control (KO OVX control), knockout colitis (KO OVX colitis), KO colitis treated with ER¿ agonist (PPT) (KO OVX Colitis + ER¿), and KO colitis treated with ER¿ agonist (DPN) (KO OVX Colitis + ER¿). All animals, except the WT control group, will undergo ovariectomy. Colitis will be induced using TNBS, and the animals will be euthanized after seven days. Immunohistochemical analyses will be performed on whole-mount preparations and cell cultures to assess neuronal markers (HuC/D, ChAT, nNOS, Calbindin) and glial markers (GFAP, S100). Western blotting will be used to quantify P2X7, ER¿, ER¿, NF-¿B, and caspase-3 expression. Intestinal motility will be evaluated using organ bath experiments with carbachol and sodium nitroprusside. Histological analysis of the colon will include PAS staining, assessment of ulcerations, and inflammatory cell infiltration. Gene expression will be analyzed by PCR. Data will be statistically evaluated using ANOVA with a significance level of 5%.