DefinePK

Abstract

This study was performed to evaluate the effects of intra-nucleus accumbens (Nacc) shell microinjection of L-arginine (a NO precursor) and NG-nitro-L-arginine metyl ester (L-NAME (a Nitric Oxide Synthase (NOS) inhibitor) on morphine withdrawal signs in male rats. Wistar rats were anaesthetized with a mixture of ketamine and xylazine, and placed in stereotaxic apparatus and a guide cannula was inserted into Nacc shell, according to the atlas of Paxinos and Watson. Morphine dependency was induced by subcutaneous administration of morphine (20 mg kg-1 for 5 days), and morphine withdrawal signs were precipitated by naloxone administration (4 mg kg-1 i.p.). Rats were received either single or repeated microinjection of saline, L-arginine or L-NAME into Nacc shell during the scheduled periods. The results of this study showed no significant difference between control and saline treated groups in the expression of morphine withdrawal signs. Single dose microinjection of L-NAME/L-arginine, just prior to the last injection of morphine, had no effect on morphine withdrawal signs, but repeated microinjection of L-arginine/L-NAME decreased jumping, rearing and weight loss (only in L-NAME group), as compared to control rats. Present results indicate that NO in Nacc shell may be involved in some of morphine withdrawal signs.