Effect of Raha syrup on the motivational effects of morphine and CSF serotonin levels in rats

Opiates may influence motivational processes by a dysregulation of brain reward pathways that play a role in context-induced reinstatement of drug seeking. Raha syrup as herbal bioactive compounds with anti-anxiety/depressant effects may be prevented morphine-induced reward and motivation effects. Therefore, the aim of this study was to investigate the effect of Raha syrup on the rewarding effects of morphine and motivational aspects of morphine-seeking behavior in morphine-induced conditioned place preference (CPP) model and also the cerebrospinal fluid (CSF) serotonin levels following the extinction and reinstatement in rats. In this study, adult male Wistar rats received Raha syrup via oral gavage to assess of the acquisition, extinction and reinstatement of the morphine-induced CPP and as well as measurement of the CSF serotonin levels. Administration of Raha syrup during the conditioning period significantly attenuated the acquisition of morphine-induced CPP, and increased the CSF serotonin level, 6 days after cessation of treatment during extinction, while did not affect the duration of the extinction period. Also, Raha syrup during the extinction period did not affect the reinstatement of morphine-induced CPP and the CSF serotonin levels in rats. We conclude that Raha syrup attenuated the acquisition of morphine reward probably through an increase in CSF serotonin, while could not maintain the extinguished CPP and had no effect on the reinstatement. Therefore, Raha syrup as a useful adjunctive therapeutic strategy may exert a protective effect against opiate-related rewards, while it may be ineffective to prevention of motivation or drug-seeking reinstatement (relapse).