Effect of single-dose oral artemether and tribendimidine on the tegument of adult Clonorchis sinensis in rats

The tegument of trematodes plays a key role in nutrient absorption, exerts secretory functions, protects the parasite against the immune system of the host, and is a target for anti-trematocidal drugs. We performed a temporal examination of tegumental changes following artemether and tribendimidine administration on adult Clonorchis sinensis in rats using scanning electron microscopy. Rats infected with C. sinensis for 6 weeks were treated orally with a single dose of artemether (150 mg/kg) or tribendimidine (300 mg/kg). Worms were collected between 8 h and 7 days (artemether) and between 4 h and 2 days post-treatment (tribendimidine). Worms recovered from untreated rats served as controls. Eight hours after artemether administration, the tegument of C. sinensis was extensively disrupted, including severe swelling, fusion and vacuolization, and the suckers were damaged. Four hours after administration of tribendimidine, C. sinensis worms showed extensive tegumental alterations, characterized by massive sloughing, and the suckers were damaged. Interestingly, the severity of tegumental changes did not progress further with time. Our results show that both artemether and tribendimidine rapidly disrupt the tegument and damage the suckers of adult C. sinensis. The subtle differences in tegumental changes induced by artemether and tribendimidine might indicate different mechanisms of action of these drugs against C. sinensis.