Abstract

This study was designed to explore the functional role of histamine H₂-receptors agonist and antagonist in the development of hepatic function impairment in immunized rabbits. The study comprised six groups containing 18 rabbits each. Group III-VI received histamine (100 µg/kg, s.c.), H₂R-agonist (amthamine, 10 µg/kg, s.c.), H₂R-antagonist (ranitidine, 10 mg/kg, i.m.), and histamine (100 µg/kg, s.c.) plus H₂R-antagonist (ranitidine, 10 mg/kg, i.m.), respectively, b.i.d. for 10 days. Group I (negative control) and group II (positive control) received sterile distilled water intramuscularly b.i.d. for 10 days. Groups II-VI were immunized on day 3 with intravenous injection of sheep red blood cells (1 × 10⁹ cells/ml). Blood samples were collected prior to immunization day 0, as well as on days 7, 14, 21, 28, and 58 post-immunization. Biochemical parameters ALT, AST, ALP, and bilirubin were determined. On each experimental day, the mean values of serum enzymes (AST, ALT, and ALP) and bilirubin (TB, DB, and IB) in negative and positive controls showed no significant changes while in group III (histamine), IV (amthamine), V (ranitidine), and VI (ranitidine+histamine), these enzymes and bilirubin levels showed significant changes (p < 0.05), when compared with their values within group. The levels of serum enzymes and bilirubin showed significant difference (p < 0.05) in the group of histamine, amthamine, ranitidine, and ranitidine+histamine on each experimental day, when compared with the corresponding values of each other, and also compared with the corresponding values of negative and positive controls. Histamine, amthamine, ranitidine, and combination of ranitidine+histamine cause liver function impairment in terms of altered serum enzymes and bilirubin levels.

Key words: Histamine, HTMT, Agonist, Antagonist, ALT, AST, ALP, bilirubin, rabbit.