Acetic Acid-Induced Colitis Model in Neonatal Rats

Overview

Model Description	The acetic acid-induced colitis model in neonatal rats is a valuable tool for studying the pathology of neonatal colitis, including its mechanisms and potential therapies. This model replicates the inflammatory processes observed in human neonatal colitis through the intrarectal administration of acetic acid, causing inflammation and ulceration in the colon.
Modeling Mechanism	Acetic acid, as a chemical irritant, can directly stimulate the intestinal mucosa, leading to epithelial necrosis and vascular injury, which in turn increases vascular permeability. Additionally, acetic acid can activate kinins, promote fibrinolysis, and interfere with the coagulation process. It also triggers inflammation by activating the cyclooxygenase and lipoxygenase pathways. Therefore, colonic administration of acetic acid can effectively induce a neonatal colitis model.
Model Characteristics	The neonatal colitis model induced by colonic administration of acetic acid effectively replicates key pathological features of human neonatal colitis, including epithelial damage and inflammatory cell infiltration. This model is also characterized by its simplicity, good reproducibility, and low cost.
Model Applications	This model is widely used to study the pathogenesis of neonatal colitis, screen potential therapeutic agents, and evaluate treatment strategies. It provides a valuable platform for identifying drugs or interventions with anti-inflammatory and immunomodulatory properties, as well as for assessing their efficacy and safety.
Modeling Method	Neonatal rats are housed in a temperature- and humidity-controlled incubator to maintain healthy growth conditions. Before induction, rats are anesthetized to minimize discomfort. Acetic acid solution, prepared at the required concentration, is administered intrarectally via a catheter, with insertion depth adjusted according to the animal’s age and size. Injection speed and volume are carefully controlled, and rats are briefly inverted post-administration to prevent leakage. Following the procedure, animals recover in an incubator and are monitored daily for body weight, food intake, and activity levels. At designated time points, rats are sacrificed, colon tissues are collected, and histopathological analyses (e.g., H&E staining) are performed to assess epithelial damage and inflammatory cell infiltration.
Therapeutic Areas	Inflammatory bowel disease (IBD)
Readouts	• Body weight and food intake changes: A decrease in body weight and reduced food intake typically indicate disease progression. • Clinical symptom observation: Monitor rats for typical symptoms such as diarrhea, bloody stools, and weight loss. • Histopathological analysis: Collect colon tissues for H&E staining to observe pathological features including epithelial damage, inflammatory cell infiltration, and ulcer formation. • Inflammatory cytokine detection: Measure the expression levels of inflammatory cytokines in colon tissues using ELISA, PCR methods to assess the degree of inflammation.