Central action of intraventricularly-injected midodrine in rats.

The aim of the present paper was to investigate the effect of intracerebroventricular (i.v.c.) injections of midodrine on the central nervous system of the rat. It was shown that midodrine increased locomotor activity, decreased body temperature, increased sedation in reserpinized rats and the cataleptic effect of haloperidol. Midodrine enhanced amphetamine-stimulated locomotor activity and reduced the amphetamine and apomorphine sterotypy. Phenoxybenzamine, yohimbine and clonidine inhibited the midodrine-induced hyperactivity. Midodrine depressed the whole brain noradrenaline (NA) and dopamine (DA) concentrations and reduced NA turnover. The results suggest a stimulating action of midodrine on the catecholaminergic neurons.