6aR-11-Amino-N-propyl-noraporphine, a new dopamine D₂ and serotonin 5-HT_1A dual agonist, elicits potent antiparkinsonian action and attenuates levodopa-induced dyskinesia in a 6-OHDA-lesioned rat model of Parkinson's disease

Parkinson's disease (PD) drug therapy remains a challenge. Dual modulation of dopamine and 5-HT receptors has emerged as a promising approach in anti-PD drug development. Taking advantage of the newly discovered aporphine analogue(s), (6aR)-11-amino-N-propyl-noraporphine (SOMCL-171), which exhibited dual D₂/5-HT_1A receptor agonistic activity, we studied the effects of the compound on levodopa-induced dyskinesia (LID) in a PD animal model. The results demonstrated that SOMCL-171 elicited a potent anti-PD effect in a 6-OHDA-lesioned rat model. Chronic use of SOMCL-171 reduced LID without compromising the antiparkinsonian efficacy. Furthermore, we found that the antidyskinesia effect of SOMCL-171 is associated with its 5-HT_1A agonistic activity and the up-regulation of the striatal 5-HT_1A receptor. The present data indicated that chronic SOMCL-171 alone produced potent antiparkinsonian effects with weak dyskinesia, compared with that of levodopa. In addition, chronic SOMCL-171 application attenuated the development of levodopa-induced LID at no expense to the antiparkinsonian efficacy. Taken together, our data suggested that dual modulation of D₂/5-HT _1A receptors may provide a novel approach for drug development in PD and LID.