The distribution of norepinephrine, dopamine and 5-hydroxytryptamine in various areas of the CNS of the normal monkey has been presented. The central levels and distribution of norepinephrine, dopamine and 5-hydroxytryptamine were determined after single doses of morphine, during maintenance of physical dependence and following withdrawal from chronic administration of morphine. Small and non-s...

      Long-term exposure to opiates induces physical dependence and tolerance. The main goal of this study was to evaluate the effects of dex...

Tolerance and physical dependence caused by chronic treatment of narcotics are good models to study basic neuronal plasticity. Activation of the NMDA subtype of the glutamate receptor has been implicated as an anti-opioid system in the development of morphine analgesic tolerance and dependence. The present study examines the specific role of the epsilon1 subunit of the NMDA receptor using mice ...

BACKGROUND Repeated morphine treatment has been shown to induce transient receptor potential vanilloid type 1 (TRPV1) expression in the spinal cord, dorsal root ganglion (DRG), and sciatic nerve of a rat model. Increased TRPV1 expression may therefore play a role in morphine tolerance. In this study, we evaluated the hypothesis that blockage of TRPV1 may be useful as an adjunctive pain manageme...

The mechanisms by which morphine-induced analgesia and tolerance and physical dependence on morphine arise have been the subject of intense study, and much work has pointed to the involvement of cAMP-mediated events in the neuroadaptive phenomena leading to morphine tolerance and/or dependence. We overexpressed an opioid receptor-stimulatable form of adenylyl cyclase (type 7) in the central ner...

cAMP response-element binding protein (CREB), a transcription factor involved in learning, memory and drug addiction, is phosphorylated by calcium-calmodulin-dependent protein kinase IV (CaMKIV). Here, we show that CaMKIV-knockout (KO) mice developed less analgesic tolerance after chronic morphine administration with no alteration in physical dependence or acute morphine-induced analgesia. The ...

Acute morphine withdrawal is considered to be the physical manifestation of dependence, emerging when morphine administration is stopped or after the administration of an opiate antagonist, such as naloxone. Gabapentin, which is an antiepileptic, agent, enhances the analgesic effect of morphine in healthy volunteers, but its effect on morphine dependence and withdrawal signs has not determined ...

The tolerance and dependence after chronic medication with morphine are thought to be representative models for studying the plasticity, including the remodeling of neuronal networks. To test the hypothesis that changes in neuronal plasticity observed in opioid tolerance or dependence are derived from increased activity of the anti-opioid nociceptin system, the effects of chronic treatments wit...