Uptake of thiabendazole and its effects on glucose uptake and carbohydrate levels in the thiabendazole-resistant and susceptible Trichostrongylus colubriformis

Sangster N. C. and Prichard R. K. 1984. Uptake of thiabenzadole and its effects on glucose uptake and carbohydrate levels in thiabendazole-resistant and susceptible Trichostrongylus colubriformis. International Journal for Parasitology14:121–126. Some possible mechanisms of thiabenzadole (TBZ) resistance have been investigated in Trichostrongylus colubriformis. Uptake of TBZ and 3-0-methyl glucose and changes in carbohydrate levels in a TBZ-resistant and a TBZ-susceptible strain of T. colubriformis were measured after in vitro incubation, in the absence or presence of TBZ. The rate of TBZ uptake in adult worms was greater in the resistant strain but the difference was not statistically significant. Final concentrations of TBZ in resistant worms were significantly greater than in the susceptible strain, but there was no difference in TBZ uptake by eggs of either strain. A mechanism of resistance based on decreased drug uptake by resistant parasites is thus unlikely. Resistant worms absorbed 3-0-methyl glucose faster than susceptible parasites, however, this rate was unchanged in either strain when the worms were exposed to TBZ and indicates that the drug does not affect glucose uptake. Levels of glucose, trehalose and glycogen fell during the incubation with the decrease being more pronounced in the resistant strain. When the worms were exposed to TBZ the same changes in carbohydrate levels occurred except for resistant worms maintained anaerobically where levels were higher, showing that TBZ does not affect the rate of carbohydrate utilization.