Preventing and reversing opioid dependence continues to be a clinical challenge and underlying mechanisms of opioid actions remain elusive. We report that matrix metalloproteinase-9 (MMP-9) in the spinal cord contributes to development of physical dependence on morphine. Chronic morphine exposure and naloxone-precipitated withdrawal increase activity of spinal MMP-9. Spinal inhibition or target...

introduction: although tolerance to and dependence on opioids are characterized by excessive activity of camp pathway in some brain stem nuclei, the impact of morphine dependence on activity of camp pathway in paragigantocellularis nucleus (pgi), located in the rostral ventrolateral medulla, remains unclear. therefore, the effect of adenyl cyclase activator forskolin on spontaneous firing rate ...

Background and Objective: Today, opioids are used to control and relieve acute and chronic pain. However, the incidence of both tolerance and dependence phenomena for these drugs is a major problem. So, in this study, the combination effect of haloperidol and methadone on the acquisition and expression of morphine dependence and tolerance was examined.    Materials and Methods: Ninety-eight mic...

This study investigated the effect of delta opioid receptor blockade by naltrindole on the development of physical dependence and tolerance to the antinociceptive and respiratory depressive effects of morphine in rats. Chronic morphine was delivered either by s.c. injection of increasing amounts of morphine over 5 days or by s.c. implantation of morphine pellets. Animals were cotreated with sal...

Objective(s):Dependence and tolerance to opioid analgesics are major problems limiting their clinical application. a-Terpineol is a monoterpenoid alcohol with neuroprotective effects which is found in several medicinal plants such as Myrtus communis, Laurus nobilis, and Stachys byzantina. It has been shown that some of these medicinal plants such as S. byzantina attenuate dependence and toleran...

combined use of an opioid with a psychostimulant is popular among drug abusers. such “polydrug use” may increase drug effects or attenuate adverse effects of either drug alone. we proposed that a combination of methamphetamine (meth) and morphine may change physical opioid withdrawal symptoms. adult male rats were chronically injected with cumulative subcutaneous (s.c.) doses of morphine, meth ...

Objectives: Dependence and tolerance are major restricting factors in the clinical use of opioid analgesics. In the present study, the effects of thymoquinone, the major constituent of Nigella sativa seeds, on morphine dependence and tolerance were investigated in mice. Materials and Methods: Male adult NMRI mice were made tolerant and dependent by repeated injections of morphine (50, 50, and 7...