EFFECTS OF FREE AND LIPOSOMIZED PRAZIQUANTEL ON THE SURFACE-MORPHOLOGY AND MOTILITY OF MESOCESTOIDES-VOGAE TETRATHYRIDIA (SYN. M-CORTI, CESTODA, CYCLOPHYLLIDEA) IN-VITRO

The effects of in vitro exposure to praziquantel (PZQ), liposomized PZ Q (lip.PZQ), and empty liposomes on the surface morphology and motilit y of Mesocestoides vogae tetrathyridia were investigated using scannin g electron microscopy (SEM) and a motility apparatus. Examination of t reated larvae showed an effect that was concentration-and time-depende nt, involving morphological damage that was similar in character for a ll of the treated groups. The most marked effects were a flattening an d elongation of the larval body accompanied by irregularities in the s urface architecture involving the development of tegumental protuberan ces and depressions. Erosion of the surface microvillous layer occurre d only after overnight incubation, being most pronounced after treatme nt with lip.PZQ. The motility index of treated tetrathyridia correspon ded well to the SEM observations. The frequency of contractions was ma ximal in worms treated with free PZQ at 25 mu g/ml in both regimens. H owever, after incubation with lip.PZQ the increase in motility was con centration-dependent and of a greater extent. Empty liposomes and lipi d mixtures of the same concentration and composition resulted in incre ased motility in treated larvae as compared with controls. More extens ive tegumental damage and higher motility of larvae occurred after lip .PZQ treatment, perhaps resulting from a synergistic action of the dru g and its associated lipid.