Effects of benzodiazepine and ivermectin on Girardiatigrina (Platyhelminthes: Turbellaria)

Abstract

Four hundred specimens of Girardia (=Dugesia) tigrina separated in groups of 5 were subjected to concentrations of 10, 25 and 50 ppm diazepam (DZP) and 1, 5 and 10 ppm of ivermectin (IVM), substances with actions associated with ionophore chlorine and GABA receptors in neuromuscular endings in various animals. The period of turbellarians exposure at different concentrations used was 3 h, for DZP while those to IVM were 30, 60, 120 minutes, 12 and 24 h for each tested concentration. In groups exposed to DZP hyperkinetic and type "C" and screw like movements were observed in all concentrations. However, at concentrations of 50 and 25 ppm, the pharynx was protruded in 100% of the specimens followed by detachment at concentration of 50 ppm and 60% at a concentration of 25 ppm. Mortality reached 100% 24 hours after exposure to a concentration of 50 ppm and 30% of planarians became degenerated at a concentration of 25 ppm. Planarians submitted to concentrations of 10 and 25 ppm remained alive and without hyperkinetic movements 48 hours after exposure. In IVM exposed groups, hyperkinetic and contractile movements were observed as well as type "C" screw like movements in all tested concentrations and time dependent. The group exposed for 24 hours showed a time dependent variation in mortality from 0 to 100%. The turbellarians were alive for 48 hours in 1 ppm during 12 hours of exposure but with 24 hours of exposure the mortality reaches 20%. The data indicate a time and concentration dependent relationship in the mode of action of these drugs.