Pharmacological blockade or genetic knockout of the NOP receptor potentiates the rewarding effect of morphine in rats.

The Nociceptin/OrphaninFQ (NOP) system is believed to be involved in drug abuse and addiction. We have recently demonstrated that activation of the NOP receptor, by systemic administration of the NOP receptor agonist Ro65-6570, attenuated the rewarding effect of various opioids in conditioned place preference (CPP) in rats and this attenuating effect was reversed by the NOP receptor antagonist J-113397. The present study demonstrates that co-administration of J-113397 (4.

Effects of the NOP receptor agonist Ro65-6570 on the acquisition of opiate- and psychostimulant-induced conditioned place preference in rats.

Activation of the Nociceptin/Orphanin FQ (NOP) receptor may have anti-abuse effects. The present study examined the consequence of NOP receptor activation on the rewarding effect of opiates and psychostimulants in the conditioned place preference task in rats. First, the motivational effect of the NOP receptor agonists Ro64-6198 (0.

The mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) potentiates conditioned place preference induced by various addictive and non-addictive drugs in rats.

We have recently reported that the metabotropic glutamate receptor 5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) potentiates acquisition of conditioned place preference (CPP) induced by heroin and ketamine. The present study investigated to what extent this effect of MPEP can be generalized to other classes of drugs, such as the stimulants nicotine and cocaine, and to drugs that produce CPP in the rat despite a lack of abuse potential in humans, such as buspirone and clonidine. Adult male Sprague Dawley rats were subjected to a standard unbiased CPP protocol (six conditioning sessions lasting 20 minutes for nicotine and 40 minutes for the other compounds).

Lack of sensitization during place conditioning in rats is consistent with the low abuse potential of tramadol.

Based on the recent finding that tramadol (TRAM) produces conditioned place preference (CPP) and dopamine release in the nucleus accumbens, it was suggested that the abuse liability of TRAM may be greater than hitherto assumed. We re-evaluated the effects of TRAM in CPP and behavioral sensitization, in comparison with morphine (MOR) and meptazinol (MEPT), an opioid drug with minimal abuse potential. While MOR produced CPP and very strong locomotor sensitization, TRAM and MEPT produced only CPP.