Dietary choline supplementation in rats increases carnitine concentration in liver, but decreases plasma and kidney carnitine concentrations

Abstract

Choline and choline-containing compounds are used in the treatment of certain neurological disorders. Limited information is available regarding the metabolic consequences of choline supplementation. The effect of both acute and chronic dietary choline supplementation on carnitine concentration in plasma, urine and tissues was studied in adult, male Sprague-Dawley rats. Eight groups of rats (n = 6/group) were assigned to four timepoints and two diets. Carnitine concentrations in choline supplemented (CS) (10 g choline chloride/kg diet) rats were measured after 1, 3, 21, and 42 days and results compared to control (C) animals (1 g choline chloride/kg). The carnitine concentration of plasma, urine, liver, heart, kidney, and gastrocnemius muscle was determined by radioenzymatic assay. Urinary choline and betaine levels were analyzed by single proton NMR spectroscopy. Both choline and betaine excretion were higher in CS animals throughout the study period. A single choline supplemented feeding (one 3 h meal) produced no significant changes in carnitine concentrations 3 h post prandial. Plasma and kidney carnitine concentrations increased over time in both dietary groups ( P = 0.0001, P = 0.0004, respectively) and choline supplementation depressed concentrations in both of these pools when compared to controls ( P = 0.0001, P = 0.006, respectively). No effect on urinary carnitine excretion was observed. Heart carnitine concentration increased over the course of the study in both dietary groups ( P = 0.006). Carnitine concentration in liver was increased due to supplementation ( P= 0.016). We conclude that the administration of a single, large dose of choline in rats does not alter carnitine concentrations during the first 3 h post prandial. Chronic choline administration decreased plasma and kidney carnitine concentrations and increased liver concentration. Choline supplementation influences the distribution of carnitine in specific body compartments, perhaps, by influencing the the transport of carnitine into or out of the liver.