• Modeling Mechanism：

  Methyl yellow, a classic azo hepatotoxic agent, undergoes oxidative demethylation and cleavage reactions in rats under the action of hepatic microsomal enzymes (such as cytochrome P450), generating active metabolites. These metabolites can bind to hepatocyte DNA, leading to base damage and gene mutations. They also interfere with endoplasmic reticulum function (inducing smooth endoplasmic reticulum proliferation and inhibiting N-demethylase activity), disrupting cellular metabolic balance, and initiating the process of precancerous lesions and tumorigenesis in hepatocellular carcinoma, mimicking the pathogenesis of chemically induced liver tumors in humans.

• Related Products：

  Methyl yellow (T81811)

• Modeling Method：

  Experimental Subject：

  Rats, Sprague-Dawley, male, body weight 250–300 g

  Dosage and Administration Route：

  ① Core modelling (acute/chronic modelling):
  - Acute modelling (short-term injury observation): Methyl orange, 300 mg/kg, dissolved in olive oil, administered via gavage after 16-hour fasting;
  - Chronic modelling (tumour induction): Methyl orange, 0.06%-0.1%, mixed into basal diet, ad libitum feeding;
  ② Control treatment: Control group administered equivalent volume of olive oil (acute modelling) or base diet without methyl yellow (chronic modelling); all other housing and treatment conditions identical;
  ③ Promoter combination (optional): Mid-modelling phase may incorporate phenobarbital (100 mg/kg/day, intraperitoneal injection, for 5 consecutive days) to accelerate hepatic tumour progression.

  Dosing Frequency and Duration Model：

  Acute modelling: single dose;
  Chronic modelling: Ad libitum feeding for 6–12 months

• Validation：

  1. Pathological Indicators: - Acute Injury: 48 hours after modeling, HE staining showed deep cytoplasmic staining of hepatocytes, pyknosis/fragmentation of nuclei around the central vein, and significant proliferation of smooth endoplasmic reticulum (reaching 262% of the control group at 48 hours), reduced rough endoplasmic reticulum, and increased autophagic vesicles and lipid droplets under electron microscopy; - Chronic Tumor: 6 months after modeling, nodular lesions appeared in the liver, and pathological sections showed abnormal proliferation and disordered arrangement of hepatocytes, forming precancerous liver lesions (such as lesions with abnormal glucose-6-phosphatase activity). Typical pathological features of hepatocellular carcinoma appeared after 12 months; 2. Enzymatic Indicators: - Serum Transaminases: Aspartate aminotransferase (AST) levels were significantly elevated, indicating persistent hepatocyte damage; - Liver Microsome Enzymes: NADPH-dependent aminopyrine N-demethylase activity decreased (down to 30% of the control group at 48 hours), and cytochrome P450 content decreased (down to 75% of the control group at 24 hours); 3. Biochemical indicators: - Liver components: Total protein content in liver tissue decreased (80% of the control group at 48 hours), RNA content decreased by 40%, and DNA content showed no significant change.

*Precautions： Rats were observed daily for their mental state and food intake. They were sacrificed in batches at 3, 6, 12, 24, 48, 72, and 120 hours. Changes in liver appearance (jaundice, fragility, granular surface) and weight were recorded.

*References：Arcasoy M,et,al. Acute effects of 3'-methyl-4-dimethylaminoazobenzene intoxication on rat liver. Structural and functional changes in the endoplasmic reticulum and NADPH-related electron transport. Am J Pathol. 1968 Apr;52(4):841-67.