Lisuride, LY-141865, and 8-OH-DPAT facilitate male rat sexual behavior via a non-dopaminergic mechanism.

In agreement with previous results from this laboratory, the ergot derivative lisuride (0.4 mg/kg IP) and the ergot congener 8-OH-DPAT (0.25 mg/kg IP) produced a marked facilitation of male rat sexual behavior. Furthermore, another ergot compound, the dopamine-2 selective agonist LY-141865 (2.5-20 mg/kg IP), was shown to facilitate male rat sexual behavior to the same degree. Neither the effects produced by LY-141865, nor the effects produced by lisuride or 8-OH-DPAT, were antagonized by pretreatment with the dopamine receptor blocking agent haloperidol, 0.16 mg/kg IP. A higher dose of haloperidol (0.32 mg IP), which produced clear extrapyramidal symptoms, was also ineffective in antagonizing the lisuride- or 8-OH-DPAT-induced facilitation of male rat sexual behavior. It is concluded that the stimulation of male rat sexual behavior produced by ergot and ergot-like drugs is mediated via a non-dopaminergic mechanism.