Effects of culture and praziquantel on membrane fluidity parameters of adult Schistosoma mansoni.

Membrane fluidity parameters, lateral diffusion coefficient and mobile fraction were assessed in male and female Schistosoma mansoni teguments immediately after their recovery from infected mice or after 24 or 48 h of culture. Our results show that male and female teguments have different properties and behave differently when in culture. In general, male worms displayed a tendency to increase their lateral diffusion coefficient while females showed a significant reduction. The effects of praziquantel (-) and praziquantel (+) on the fluidity properties of the worm surface were also studied. It was demonstrated that both enantiomers of the drug interact with the tegument inducing a decrease in the average velocity of lipid molecules. However, it is only the active form which reduces the number of molecules that are able to move. In explanation we propose that praziquantel (-) and praziquantel (+) have different ways of inserting into the tegument and that some of the effects of the drug are mediated by altering membrane fluidity.