It has been reported that morphine tolerance does not develop in the presence of chronic pain. Therefore, this study was conducted to find out whether chronic inflammatory pain is able to eliminate or attenuate the developed tolerance to analgesic effect of morphine and also to investigate the role of lumbar spinal cord as a candidate site for this interaction. Tolerance was induced in adult ma...

In our previous study, we reported that chronic morphine exposure changes neuronal response properties in rat somatosensory cortex. In this study, we investigated the effect of chronic morphine treatment on tactile learning behavior in rats. Morphine sulfate was dissolved in tap water, and was administered for 21 days. Tactile learning was assessed using the novel object recognition test (NORT)...

Introduction: Our previous study has showed that chronic administration of magnesium oxide nanoparticles (MgO NP) can reduce anxiety in adult male rat. In this study the effects of MgO NP on anxiety induced by morphine withdrawal were investigated in adult male mice. Methods: Adult male NMRI mice (weighing 27 ± 3 g) divided into groups: control, receiving intraperitoneal (i.p.) injection...

there is growing evidence indicating that neuronal calcium channels play an important role in the mechanism of morphine dependence. in this study, the effects of acute and chronic administration of nitrendipine on naloxone precipitated morphine withdrawal signs were investigated. mice were rendered dependent to morphine by subcutaneous injection of morphine over a period of 5 days. in chronic s...

Morphine is a psychoactive medication that is used as a standard analgesic treatment to relieve pain in clinics. Many patients rely on chronic or acute treatment of morphine to treat pain. However, morphine is a narcotic and has a reverse effect when inappropriately used. Therefore, it is necessary to study chronic and acute morphine treatment to improve pain relief. In this study, differential...

  Tolerance and dependence are two main problems that have limited morphine administration as an analgesic drug and they might be as a result of changes in the number and affinity of receptors, dysfunction of adenylate cyclase, impaired coupling between activated µ receptor and K+ channels, and changes in the K+ and Ca2+ channels. There are several reports concerning the role of some of these...

There is some evidence supporting the reduced activity of integrins following chronic administration of morphine. This reduction might play a role in morphine tolerance development. Manganese binds to the extracellular domain of integrins and makes them to be activated. The effect of integrins activation using manganese on tolerance development to the analgesic effect of morphine was investi...

There is growing evidence indicating that neuronal calcium channels play an important role in the mechanism of morphine dependence. In this study, the effects of acute and chronic administration of nitrendipine on naloxone precipitated morphine withdrawal signs were investigated. Mice were rendered dependent to morphine by subcutaneous injection of morphine over a period of 5 days. In chronic s...

there is some evidence supporting the reduced activity of integrins following chronic administration of morphine. this reduction might play a role in morphine tolerance development. manganese binds to the extracellular domain of integrins and makes them to be activated. the effect of integrins activation using manganese on tolerance development to the analgesic effect of morphine was investigat...

Spinal NMDA receptor (NMDAR), protein kinase C (PKC), and glucocorticoid receptor (GR) have all been implicated in the mechanisms of morphine tolerance; however, how these cellular elements interact after chronic morphine exposure remains unclear. Here we show that the expression of spinal NMDAR and PKCgamma after chronic morphine is regulated by spinal GR through a cAMP response element-bindin...