The central antiserotonergic action of mianserin

The central antiserotonergic action of mianserin (MS) was tested in mice, rats, and rabbits. MS, like cyproheptadine, to which it was compared, inhibits the head-twitch response to 5-hydroxytryptophan in mice and rats without affecting the pinna reflex. MS does not change the flexor reflex of the hind limb of the spinal rat; it antagonizes its stimulation induced by fenfluramine, LSD, and quipazine, but not that induced by clonidine. The hyperthermia in rabbits caused by the serotonergic stimulants cited above is also antagonized by pretreatment with MS. Unlike cyproheptadine, MS is not active in the oxotremorine test. The results indicate that at low doses MS is a central serotonergic-receptor blocker.