Effect of praziquantel on ultrastructures of gut epithelia of Clonorchis sinensis

Praziquantel was given intragastrically to rats at a single dose of 300 mg/kg two months after infection with Clonorchis sinensis. The electron microscopy of Clonorchis sinensis removed from the rats 1-36 h after medication showed some changes in the gut epithelia. One hour after medication the distal microvilli(lamellae) were slightly swollen at some places and the dots within the microvilli became indistinct or even disappeared, and the granular endoplasmic reticuli(GER) were mostly expanded, 3-6 h part of the microvilli were adhered to each other and the granular endoplasmic reticuli were further expanded, 12-24 h partial lysis of the microvilli occurred, 36 h the distal microvilli were further lysed and degenerated. The results showed that praziquantel has a remarkable damaging effect on the gut microvilli. The damage tended to be greater the longer after the medication. And the nearer the place was to the gut lumen, the severer the damage would be.