The influence of rolipram on the central serotoninergic system.

The influence of rolipram, a potential psychotropic drug, on the central serotoninergic system was studied. Rolipram was found to elicit the head twitch reaction in rats but not in mice. This effect was abolished by phenoxybenzamine, clonidine and morphine but not by cyproheptadine, metergoline and pizotifen. The antagonistic action of morphine was reversed by naloxone. Rolipram stimulated the flexor reflex of the hind limb in the spinal rat but this effect was blocked neither by cyproheptadine and pizotifen, nor by phenoxybenzamine. In rats kept at a high ambient temperature, rolipram induced slight hypothermia and did not affect the hyperthermia induced by fenfluramine. Rolipram produced also slight hypothermia in rabbits. Our results indicate that rolipram does not affect the central serotoninergic transmission but in some of its central effects (the head twitch reaction) the noradrenergic system and the opiate receptors seem to be involved.