The role of neuropeptide FF (NPFF) in the expression of sensitization to hyperlocomotor effect of morphine and ethanol

Abstract Neuropeptide FF (NPFF) has been characterized as an endogenous anti-opioid peptide because its intraventricular injection (icv) reversed morphine- and stress-induced analgesia, and precipitates withdrawal syndrome in morphine-dependent rats. The role of NPFF in other aspects of drug dependence is unknown. Therefore, the aim of this study was to determine NPFF influence on the expression of sensitization to the morphine-induced hyperlocomotion. As the opioid system plays a role in ethanol effects, the influence of NPFF on the expression of sensitization to hyperlocomotor effect of ethanol was also investigated. Our study indicated that acute administration of NPFF (5, 10, 20nmol, icv) inhibited the expression of morphine-induced sensitization at doses of 10 ( P P P In conclusion, our experiments indicated that NPFF attenuated the acute morphine locomotion and the expression of sensitization to locomotion. We anticipate that NPFF may be involved in both of these effects.