The effects of chlorimipramine and protriptyline on tube running activity in mice

We have developed a new technique, tube running activity, to study the effects of drugs on a specific behaviour in mice. The time it takes for a mouse to run 100 cm in a narrow tube is measured. The effects on tube running activity of chlorimipramine, a relatively specific blocker of the amine pump in the 5-hydroxytryptaminergic neurons, and protriptyline, a relatively specific blocker of the amine pump in the noradrenergic neurons, were studied. During the first two hours after the administration of chlorimipramine 7.5 mg/kg IP there was a decreased run time as compared with controls. The run time could not be further decreased by increasing the dose of chlorimipramine, but the effect was prolonged. Protriptyline in the dose range of 3.75-30 mg/kg IP had no observable effect on the run time, but protriptyline 60 mg/kg IP decreased the run time in the same way as chlorimipramine 60 mg/kg IP did. The decreased run time after protriptyline 60 mg/kg IP is probably due to a blockade of the amine pump in the 5-hydroxytryptamine neurons at this high dose. Our results suggest that tube running activity more specifically measures functional effects of 5-hydroxytryptamine than functional effects of noradrenaline.