Pharmacodynamic Modulation of Motility by Glycine Administration in Dugesia Dorotocephala

The glycinergic neurotransmission system is a potential pharmacological target for pain and muscle spasm relief therapy. Planarians are attractive model organisms for neuropharmacological research, due to their simplicity and neurotransmitters shared with mammals. In this study, planarians were exposed to glycine, caffeine, midazolam and ondansetron separately and to successive associations of glycine/caffeine, glycine/midazolam and glycine/ondansetron. Effects on motility were examined by a grid crossing assay. Results showed a dose-dependent reduction of motility by glycine, partially reversed by caffeine and midazolam, but not by ondansetron. Midazolam caused an intense decrease of motility, but not significantly lower than glycine. Ondansetron-treated planarians showed decrease motility compared with controls, but not with glycine or midazolam. These results are consistent with data obtained from higher organisms, showing that planarians can be used as model organisms for glycinergic pharmacological research.