Abstract: AIM: To study the action mode of cyclosporin A (CsA) against Schistosoma mansoni in vitro
.METHODS: MF1 mice were infected with Schistosoma mansoni cercariae for 6 weeks when the adult worms were
recovered by portal perfusion. The male worms of S.mansoni recovered were exposed to varying concentrations of
CsA at 8, 16, and 24 h in vitro .Drug induced damage to the male worm surface was chronobiologically observed
throughout these experiments by SEM. RESULTS: After the male worms of S. mansoni were incubated with 1 ug/ml CsA for 8-24 h, the tegument showed swelling of ridges with appearance of holes on their surface and detachment of a part of spines. The above damage of the tegument became more evident in male worms after incubation with 10, 15, 20 ug/ml CsA for 8- 24 h. Moreover, incubation of male worms with 25 ug/ml CsA for 8-24 h resulted in significant deformation and disruption of tegument, rupture of ridges and detachment of spines. The tegumental damage of male worms of S. mansoni was dose- and time-dependen t. CONCLUSTION: The antischistosomal action of CsA is direct, the chistosome tegument appears to be the main site for CsA attack.

Key words: Cyclosporin A （CsA）, Schistosoma mansoni, male worm, SEM, chronobiology