introduction: sex differences are observed in the development of tolerance to antinociceptive effect of opioid drugs such as morphine, but the underlying mechanisms remain unclear. critical role of glutamate in the development and maintenance of opioid tolerance has been reported by many investigators. there are also evidences about interaction between gonadal hormones and neuromodulatory syste...

Objective: Opiate addiction is characterized by compulsive drug use and severe withdrawal symptoms during abstinence. Heantos 4, an herbal pharmacotherapy recently approved for opiate withdrawal treatment in Vietnam, has shown anti-craving properties. The present study is the first preclinical assessment of the effects of Heantos 4 on opiate withdrawal and the rewarding properties of morphine, ...

INTRODUCTION Activation of N-methyl-d-aspartate (NMDA) glutamate receptors in the nucleus accumbens is a component of drug-induced reward mechanism. In addition, NMDA receptors play a major role in brain reward system and activation of these receptors can change firing pattern of dopamine neurons. Blockade of glutamatergic neurotransmission reduces the expression of conditioned place preference...

Learned associations between environmental cues and morphine use play an important role in the maintenance and/or relapse of opioid addiction. Although previous studies suggest that context-dependent morphine treatment alters glutamatergic transmission and synaptic plasticity in the hippocampus, their role in morphine conditioned place preference (CPP) and reinstatement remains unknown. We inve...

Morphine loses analgesic potency after repeated administration. The underlying mechanism is not fully understood. Glia are thought to be involved in morphine tolerance, and P2X7 purinergic receptor (P2X7R) has been implicated in neuron– glia communication and chronic pain. The present study demonstrated that P2X7R immunoreactivity was colocalized with the microglial marker OX42, but not the ast...

As long-term opioids are increasingly used for control of chronic pain, how pain affects the rewarding effect of opioids and hence risk of prescription opioid misuse and abuse remains a healthcare concern and a challenging issue in current pain management. In this study, using a rat model of morphine self-administration, we investigated the molecular mechanisms underlying the impact of pain on ...

Morphine loses analgesic potency after repeated administration. The underlying mechanism is not fully understood. Glia are thought to be involved in morphine tolerance, and P2X(7) purinergic receptor (P2X(7)R) has been implicated in neuron-glia communication and chronic pain. The present study demonstrated that P2X(7)R immunoreactivity was colocalized with the microglial marker OX42, but not th...

Drug addiction is increasingly viewed as the expression of abnormal associative learning following repeated exposures to the drugs of abuse. Previous studies have demonstrated that the patterns of repetition such as frequency and spacing are important to many kinds of learning and memory retention. We hypothesized that drug repetition pattern might affect the reward-related learning although th...

BACKGROUND Stump and phantom pains are debilitating sequelae of amputations that are often resistant to treatment. The efficacy of pharmacologic therapies, including opioids and sodium channel blockers, for postamputation pain is uncertain. METHODS The authors conducted a double-blind, randomized, placebo-controlled, crossover study in adult patients with postamputation pain of 6 months or lo...