Magnetic resonance spectroscopy (MRS) was employed to investigate alterations in carbohydrate and lipid metabolism in livers of mice infected with the cysticerci of Taenia crassiceps. Livers of control and infected mice were removed and their perchloric extracts prepared. Two hours after intraduodenal injection of (3-{13}C) alanine, liver extracts from both control and infected groups of mice contained {13}C label in glycogen, glucose, succinate, glutamate, alanine and lactate. Livers of infected mice had a lower percentage of {13}C in alanine and lactate than controls. In addition, infected mice had a lower concentration of total hepatic glucose and glutamate, but higher concentration of betaine, acylcarnitine and [beta]-hydroxybutyrate. T. crassiceps larvae also possessed {13}C label in glucose, acetate, alanine and lactate. When (3-{13}C) lactate was used as the gluconeogenic substrate, a lower percentage of {13}C was present in glycogen, succinate, glutamate, acetate and lactate in livers of infected mice than in controls. Infected mice also had lower concentrations of hepatic glucose and phosphocholine, but higher concentrations of betaine, choline, acylcarnitine and [beta]-hydroxybutyrate. Cysticerci contained {13}C label in glucose, alanine and lactate. Chloroform/methanol xtracts of livers from infected mice showed lower concentrations of total fatty acid (FA), phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, total glycerophospholipids and triacylglycerols than controls than those of normal livers. Cholesterol concentrations remained unchanged. Furthermore, the liver extracts of animals infected with cysticerci had higher ratios of the polyunsaturated moieties to total FA, but lower ratios of the saturated moieties. Extracts of T. crassiceps displayed a similar lipid profile to that of host liver but contained a lower lipid content and a shorter average FA chain length. (Abstract shortened by UMI.)