Coptisine ameliorates colitis in mice by modulating cPLA2/TRPM8/CGRP-1 signaling pathways and strengthening intestinal barrier function

Abstract

Coptisine (COP), a naturally occurring alkaloid, is recognized for its varied pharmacological impacts and its supportive function in intestinal well-being. However, the role of COP to protect the colonic epithelium in colitis has not been extensively investigated. The objective of this study was to assess the efficacy of COP in ameliorating colitis by investigating intestinal histopathology, mucosal barrier function, and transient receptor potential (TRP) signaling pathways in mice with colon disease compared to a control group, thereby elucidating the underlying mechanisms of its action. The results demonstrated a marked improvement in diarrhea and bleeding, an improvement in general behavioral competencies of the mice, and a decrease in disease activity index (DAI) scores. Histopathological analysis indicated a reduction in intestinal inflammation and an enhancement of intestinal mucosal barrier function. Our research identified that the protein expressions of the TRP family including transient receptor potential cation subfamily M member 8 (TRPM8), transient receptor potential vanilloid 1 (TRPV1), and transient receptor potential ankyrin 1 (TRPA1) were significantly upregulated with COP treatment. Compared with the model, COP markedly downregulated cytosolic phospholipase A2 (cPLA2) levels, while upregulating calcitonin gene-related peptide-1 (CGRP-1) protein expressions. Our study revealed that COP enhanced intestinal barrier function by modulating the cPLA2/TRPM8/CGRP-1 signaling pathway, thus shedding light on the mechanism by which COP mitigates inflammation in the intestinal mucosa. These findings provided new insights on COP as a therapeutic agent in ulcerative colitis (UC).