The novel neuropeptide orphanin FQ fails to produce conditioned place preference or aversion.

An unbiased conditioned place preference procedure was used to determine whether the newly-identified neuropeptide orphanin FQ produced motivational effects after intracerebroventricular microinjections. Microinjections of orphanin FQ (0.1-100 nmol) failed to produce conditioned place preference or aversion, but a pronounced motor impairment was observed during conditioning sessions with the two highest doses. Thus, it appears that orphanin FQ lacks motivational effects when administered at behaviourally active doses.