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Hypothyroidism minimizes liver damage and improves survival in rats with thioacetamide induced fulminant hepatic failure
Author(s) -
Bruck Rafael,
Oren Ran,
Shirin Haim,
Aeed Hussein,
Papa Moshe,
Matas Zipora,
Zaidel Liliana,
Avni Yona,
Halpern Zamir
Publication year - 1998
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.510270417
Subject(s) - thioacetamide , medicine , endocrinology , propylthiouracil , fulminant hepatic failure , hyperdynamic circulation , hepatic encephalopathy , necrosis , cirrhosis , thyroid , portal hypertension , liver transplantation , transplantation
Recent data from animal studies suggest that induced hypothyroidism prevents the hyperdynamic circulation in portal vein ligated rats, liver cirrhosis in rats chronically treated with thioacetamide (TAA), and immune‐mediated acute liver injury induced in mice by concanavalin A. Therefore, the aim of this present study is to determine whether hypothyroidism would likewise prevent fulminant hepatic failure (FHF) in rats. FHF was induced by 3 consecutive ip injections of TAA (400 mg/kg) at 24‐hour intervals. Hypothyroidism was induced in rats by either methimazole (MMI) or propylthiouracil (PTU) and surgical thyroidectomy and was confirmed by elevated serum thyroid stimulating hormone levels. Serum levels of liver enzymes, blood ammonia, and prothrombin time were significantly lower in all 3 groups of hypothyroid rats. The stage of hepatic encephalopathy (HE) and the survival rates were significantly improved in the hypothyroid rats ( P < .01); the histologic examination of their livers showed less necrosis and inflammation ( P < .01). In the hypothyroid rats, the serum levels of malondialdehyde 48 hours after thioacetamide (TAA) administration were lower than in control rats ( P < .01). Exogenous supplementation of hypothyroid rats with l ‐thyroxine started 48 hours before TAA administration abrogated the protective effects of hypothyroidism. The serum levels of tumor necrosis factor alfa (TNF‐α), interleukin (IL) 2 and IL‐6 after 24 hours were slightly lower in the hypothyroid rats, but the administration of soluble receptor of TNF (10‐1,000 μg/rat) did not prevent the induction of fulminant liver failure by TAA. Oxygen extraction, studied in isolated perfused liver preparation, was significantly lower in livers of hypothyroid rats ( P < .01). These results suggest that induced hypothyroidism decreases the development of liver injury in a rat model of FHF. The mechanism may involve diminished oxidative cell injury caused by decreased oxygen utilization and hypometabolism associated with hypothyroidism.