The central action of 1-(2-pyrimidinyl)-piperazine, an ipsapirone metabolite

The central action of 1-(2-pyrimidinyl)-piperazine (1-PP), a metabolite of ipsapirone, was studied in mice and rats. 1-PP decreased the locomotor activity and slightly increased the body temperature at an ambient temperature of 21 degrees C, not changing it at an ambient temperature of 28 degrees C. The examined substance antagonized clonidine effects (hypothermia, locomotor hypoactivity, stimulation of the hind limb flexor reflex of the spinal rat). Stimulation of the flexor reflex by St 587, an alpha 1-adrenoceptor agonist was not blocked by 1-PP. 1-PP-induced stimulation of the flexor reflex was blocked by cyproheptadine, ketanserin and pirenperone, but not by prazosin or yohimbine. Given in high doses, 1-PP evoked a flat body posture syndrome, but not forepaw treading or head twitches. The obtained results indicate that 1-PP has mainly an alpha 2-adrenolytic action and differs from ipsapirone in its profile.