Digestive System

Inflammatory Bowel Disease (IBD) Model

• Ulcerative Colitis (UC) Model: Typically induced by dextran sulfate sodium (DSS) in drinking water or oxazolone, affecting the colon.
• TNBS-Induced Colitis Model: Utilizes 2,4,6-trinitrobenzenesulfonic acid (TNBS) with ethanol as a haptenizing agent, primarily modeling T-cell mediated inflammation that shares features with human Crohn's disease.

Irritable Bowel Syndrome (IBS) Model

Often induced by neonatal maternal separation, colonic instillation of acetic acid, or chronic stress to mimic visceral hypersensitivity and motility disorders.

Colorectal Cancer Model

• Chemically-induced: Azoxymethane (AOM) injection, often combined with DSS to model colitis-associated cancer.
• Genetically Engineered: Apc^Min/+ mice for spontaneous intestinal adenoma development.
• Xenograft: Implantation of human colorectal cancer cells.

Intestinal Obstruction & Surgical Models

• Intestinal Obstruction Model: Created by surgical ligation of a small intestinal segment.
• Small Intestine Anastomosis Model: Involves transection and surgical reconnection to study healing and leakage.
• Small Intestine Adhesion Model: Induced by abrasion of the serosal surface to study post-surgical adhesion formation.

Intestinal Ischemia & Injury Models

• Intestinal Ischemia-Reperfusion Injury Model: Induced by clamping the superior mesenteric artery (SMA).
• Abdominal Impact-Induced Intestinal Injury Model: Utilizes a controlled impact device to simulate blunt trauma.

Other Intestinal Pathophysiology Models

• Short Bowel Syndrome Model: Created by massive surgical resection of the small intestine.
• Intestinal Fibrosis Model: A chronic outcome in models like repeated DSS cycles or TNBS-induced colitis.
• Total Parenteral Nutrition (TPN) Model: Involves intravenous feeding via a central venous catheter, leading to gut mucosa atrophy.
• Gut Microbiota Models: Gut Microbiota Colonization Model (using germ-free animals); Gut Dysbiosis Model (induced by antibiotics or specific diets, e.g., high-fat).
• Rectal Prolapse Model: Can occur spontaneously in certain genetic strains or be surgically induced.

Systemic Infection Model

• Sepsis Model (Intestinal Origin): Most commonly induced by cecal ligation and puncture (CLP), which mimics polymicrobial sepsis stemming from intestinal perforation and is critical for studying intestinal barrier failure and systemic inflammatory response.

Metabolic & Alcohol-Associated Liver Disease

• Non-Alcoholic Fatty Liver Disease (NAFLD) Model: Induced by high-fat diets (HFD) or methionine-choline deficient (MCD) diet.
• Nonalcoholic Steatohepatitis (NASH) Model: A progressive form of NAFLD, induced by MCD diet, HFD with fructose/ sucrose, or AMLN diet.
• Alcohol-Induced Cirrhosis Model: Created by chronic ethanol feeding (e.g., NIAAA model).
• Chronic Alcoholism Model: Focuses on systemic effects of chronic ethanol intake.

Hepatitis & Infectious Liver Disease

• Hepatitis Model: Can be chemically induced (e.g., Concanavalin A for immune-mediated hepatitis) or based on viral infection (e.g., HBV, HCV).
• HBV Transgenic Model: Genetically engineered mice carrying the HBV genome, capable of supporting viral replication and gene expression, widely used for studying viral persistence and immunopathogenesis.

Liver Fibrosis & Cirrhosis

• Hepatic Fibrosis Model: The most common method is repeated carbon tetrachloride (CCl₄) injections or bile duct ligation.
• Liver Cirrhosis Model: The end-stage of fibrosis, achieved through prolonged CCl₄ administration or chronic TAA exposure.
• Chronic Liver Failure Model: Represents the decompensated stage of cirrhosis, typically achieved through prolonged CCl₄ or TAA administration, characterized by ascites, jaundice, and coagulopathy.

Liver Injury & Regeneration

• Acute Liver Injury Model: Induced by a single high dose of CCl₄ or acetaminophen (APAP).
• Hepatectomy (Regeneration) Model: Involves surgical partial removal of the liver (e.g., 70% hepatectomy) to study regenerative mechanisms.

Liver Cancer & Transplantation

• Liver Cancer Model: Induced by diethylnitrosamine (DEN) injection in mice, or developed from chronic fibrosis/cirrhosis models.
• Liver Transplantation Model: A microsurgical model in rodents for studying transplant immunology and organ preservation.

Gastric Ulcer & Injury Models

• Gastric Ulcer Model: Induced by acetic acid application to the serosal surface, cold-restraint stress, or pylorus ligation.
• Acute Gastric Mucosal Injury Model: Induced by high-dose ethanol, indomethacin, or stress.
• Gastritis Model: Can be induced by Helicobacter pylori infection or chemical irritants like DSS.
• Gastric Bleeding Model: Often assessed within acute injury models or created by direct mucosal vessel damage.

Esophageal Disease Models

• Reflux Esophagitis Model: Created by pylorus and forestomach ligation to induce acid reflux.
• Gastroesophageal Reflux Disease (GERD) Model: A chronic version of the reflux model, sometimes combined with a hiatal hernia procedure.

Biliary Disease Models

• Bile Duct Ligation and Recanalization Model: Ligation is the standard for obstructive cholestasis and fibrosis. Surgical recanalization (de-ligation) is technically challenging, primarily in rodents, and is used to study the regression of biliary injury and fibrosis.
• Cholestasis Model: Primarily induced by bile duct ligation or administration of α-naphthylisothiocyanate (ANIT).
• Jaundice Model: A symptom often observed in cholestasis and liver failure models.

Pancreatic Disease Models

• Pancreatitis Model: Acute form induced by cerulein hyperstimulation or bile duct infusion; Chronic form induced by repeated cerulein injections.
• Pancreatic Cancer Model: • Genetically Engineered: Kras mutations combined with Trp53 or Cdkn2a deletion (e.g., KPC model). • Xenograft: Implantation of human pancreatic cancer cells. • Chemically-induced: Carcinogen administration (e.g., N-Nitrosobis(2-oxopropyl)amine (BOP) in hamsters) models the multistep progression of pancreatic ductal adenocarcinoma.

Other GI Cancer Models

• Esophageal Cancer Model: Induced by chronic nitrosamine exposure or surgical esophagojejunostomy to model Barrett's esophagus and adenocarcinoma.