title: Noni (Morinda citrifolia L.) fruit extract attenuates the rewarding effect of heroin in conditioned place preference but not withdrawal in rodents.
abstract: The present study was designed to investigate the effect of a methanolic extract of Morinda citrifolia Linn. fruit (MMC) on the rewarding effect of heroin in the rat conditioned place preference (CPP) paradigm and naloxone-precipitated withdrawal in mice. In the first experiment, following a baseline preference test (preconditioning score), the rats were subjected to conditioning trials with five counterbalanced escalating doses of heroin versus saline followed by a preference test conducted under drug-free conditions (post-conditioning score) using the CPP test. Meanwhile, in the second experiment, withdrawal jumping was precipitated by naloxone administration after heroin dependence was induced by escalating doses for 6 days (3×/ day). The CPP test results revealed that acute administration of MMC (1, 3, and 5 g/kg body weight (bw), p.o.), 1 h prior to the CPP test on the 12th day significantly reversed the heroin-seeking behavior in a dose-dependent manner, which was similar to the results observed with a reference drug, methadone (3 mg/kg bw, p.o.). On the other hand, MMC (0.5, 1, and 3 g/kg bw, p.o.) did not attenuate the heroin withdrawal jumps precipitated by naloxone. These findings suggest that the mechanism by which MMC inhibits the rewarding effect of heroin is distinct from naloxone-precipitated heroin withdrawal.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Megala
authors.initials: M
authors.lastname: Narasingam
authors.forename: Vijayapandi
authors.initials: V
authors.lastname: Pandy
authors.forename: Zahurin
authors.initials: Z
authors.lastname: Mohamed
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology*; D005638:Fruit / Q000737:chemistry; D003932:Heroin; D008297:Male; D008813:Mice, Inbred ICR; D023421:Models, Animal; D032066:Morinda / Q000737:chemistry*; D009270:Naloxone; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use*; D017207:Rats, Sprague-Dawley; D012054:Reinforcement, Psychology; D012201:Reward; D013375:Substance Withdrawal Syndrome; D019966:Substance-Related Disorders / Q000188:drug therapy* / Q000523:psychology*
chemical_list: D010936:Plant Extracts; D009270:Naloxone; D003932:Heroin