there are several conflicting evidences showing the effect of morphine on learning and memory processes. in the present study the effect of chronic morphine administration on passive avoidance, active avoidance and spatial learning and memory of morphine dependent male rats using passive avoidance shuttle box and morris water maze tasks were investigated, respectively. male rats received morphi...

In morphine tolerance a key question that remains to be answered is whether mu-opioid receptor (MOPr) desensitization contributes to morphine tolerance, and if so by what cellular mechanisms. Here we demonstrate that MOPr desensitization can be observed in single rat brainstem locus coeruleus (LC) neurons following either prolonged (> 4 h) exposure to morphine in vitro or following treatment of...

introduction: in order to study the alterations of beta 1 and 2 integrins mrna level in rat lumbar spinal cord following the induction of chronic pain and its effect on the development of tolerance to morphine analgesia, we examined the level of expression of these genes in the presence of chronic pain, which is an inhibitor of morphine tolerance. we used induction of chronic pain alone and in ...

R.J. KOSLO, J.L. VAUGHT, A. COWAN, D.E. G M E R E K and F. PORRECA, lntrathecal morphine slows gastrointestinal transit in rats, European J. Pharmacol. 119 (1985) 243-246. Intrathecal (i.th.) (by direct lumbar puncture) and intraperitoneal (i.p.) administration of morphine (30-100/~g/rat) caused a dose-related inhibition of gastrointestinal transit in the rat. Pretreatment with i.th. naloxone (...

Background: Previous studies have confirm the effects of water extract of Crocus sativus on the euphoric and behavioral properties of morphine in mice. Objective: In the present study, the effects of intra-accumbal administration of alcohol extract of Crocus sativus stigma on the acquisition and expression of morphine-induced conditioned place preference (CPP) in male Wistar rats (250-300 g...

A recent report showed that morphine inhibited [3H]clonidine binding to human platelet alpha 2 receptors. As the analgesic effects of morphine and clonidine are clinically additive, we investigated the possibility that morphine might stimulate alpha 2 receptors or alpha 2 mechanisms in rat locus coeruleus (LC) slices. Stimulated LC noradrenaline efflux was measured by fast cyclic voltammetry. C...

post operative pain and its control remains one of the most important issues in the field of surgery and health care system. formalin test has been used as a method for assessing pain and analgesia in rats. systemic and spinally administered clonidine, an ?2-adrenergic agonist, is proved to enhance postoperative analgesia. it has also been shown that morphine-dependent rats experience more chro...

Background: Role of nitric oxide (NO) on expression of morphine conditioning using a solely classic task has been proposed previously. In this work, the involvement of NO on the expression of opioid-induced conditioning in the task paired with an injection of naloxone was investigated. Methods: Conditioning was established in adult male Wistar rats (weighing 200-250 g) using an unbiased procedu...

morphine and tramadol which have analgesic effects can be administered acutely or chronically. this study tried to investigate the effect of these drugs at various times by using different methods of administration (intraperitoneal, oral, acute and chronic). sixty adult female rats were divided into six groups. they received saline, morphine or tramadol (20 to 125 mg/kg) daily for 15 days. a ho...