Schistosoma mansoni: suppression of carbamoyl phosphate synthetase (ammonia) and ornithine carbamoyltransferase activities in the liver of infected mice.

ICR female mice infected with cercariae of Schistosoma mansoni exhibited a significant decrease in both total and specific activities of carbamoyl-phosphate synthetase (ammonia) (EC 6.3.4.16) and ornithine carbamoyltransferase (EC 2.1.3.3), and also in the serum urea level. Intraperitoneal administration of the S. mansoni egg granulomas or 15,000g X 30 min supernatant fluid of their extract into the uninfected, normal mice also significantly decreased the total and specific activities of both enzymes without any appreciable histopathological influence on their livers. S. mansoni viable eggs caused a significant decrease in the total and specific activities of carbamoyl phosphate synthetase (ammonia) alone as well as active intraperitoneal inflammation when inoculated into the normal mice by the same route. There was no difference in the amount of food intake between the control and these experimental mice. These findings suggest that the granuloma or inflammatory cells induced by schistosome eggs produce some factor(s) which may be responsible for reduction of these enzymatic activities in experimental schistosomiasis mansoni.