Abstract
We developed a new method of drug administration for planaria. A syringe fixed to a microinjector was connected to an injection needle with a flexible vinyl tube. This flexible tube helped to guide the needle to the exact administration point of the body. A precise amount of drug can be administered by the operation of the microinjector. We obtained a dose-response curve of immobilization after urethane administration (400 mg/kg-3200 mg/kg). Stable immobilization was observed after 1600 mg/kg administration, and the average duration of immobilization was 8 min. The effective dose 50% (ED50) estimated by the interpolation of the data between 800 mg/kg and 1600 mg/kg groups was 933 mg/kg.
