Effect of intraperitoneal sublethal doses of dimethoate on rat hepatic gluconeogenesis

ABSTRACT

Male Wistar rats were injected with dimethoate [10 mg/0.5ml saline i.e. 5% LD[50]] intraperitonitally for 7 successive days. Treated animals suffered from a significant loss in body weight and liver weight as compared to control group. The gluconeogenic enzymes; phosphoenolpyruvate carboxykinase [PEPCK] and fructose 1, 6- bishosphatase [FBPase] were examined in liver. The activity of both enzymes decreased significantly in the treated group. PEPCK and FBPase activities were measured in vitro in the presence and absence of different concentrations of dimethoate. Addition of dimethoate to the reaction mixture resulted in a decrease in the activity of both enzymes. PEPCK activity was inhibited by 1mM dimethoate [28% inhibition] while FBPase activity showed a 30% inhibition by 0.5 mM dimethoate. Addition of 5 mM dimethoate caused 45% and 50% inhibition to PEPCK and FBPase, respectively. Lineweaver- Burk plot of PEPCK and FBPase activity at different substrate concentrations in the presence and absence of 2 mM dimethoate gave an uncompetitive type of inhibition