objective(s): we aimed to examine association of gene expression of mor1 and glun1 at mrna level in the lumbosacral cord and midbrain with morphine tolerance in male wistar rats. materials and methods: analgesic effects of morphine administrated intraperitoneally at doses of 0.1, 1, 5 and 10 mg/kg were examined using a hot plate test in rats with and without a history of 15 days morphine (10 mg...

introduction: association between single-nucleotide polymorphisms (snps) in mu opioid receptor gene and drug addiction has been shown in various studies. here, we have evaluated the existence of polymorphisms in exon 3 of this gene in iranian population and investigated the possible association between these mutations and opioid addiction.  methods: 79 opioid-dependent subjects (55 males, 24 fe...

Introduction: Association between single-nucleotide polymorphisms (SNPs) in mu opioid receptor gene and drug addiction has been shown in various studies. Here, we have evaluated the existence of polymorphisms in exon 3 of this gene in Iranian population and investigated the possible association between these mutations and opioid addiction.  Methods: 79 opioid-dependent subjects (55 males, 24...

Regulation of the mu-opioid receptor gene by opioid analgesic drugs has not been observed in rats and mice following in vivo treatments that produce tolerance. Although in vivo heterologous regulation of mu-opioid receptor mRNA by non-opioid compounds has been reported, the failure to observe changes in mu-opioid receptor mRNA levels in vivo after treatment with opioid agonists raised the possi...

Opioid agonists and antagonists can regulate the density of mu-opioid receptors in whole animal and in cell culture. High intrinsic efficacy agonists (e.g., etorphine), but not lower intrinsic efficacy agonists (e.g., morphine), produce mu-opioid receptor down-regulation and can alter the abundance of mu-opioid receptor mRNA. Conversely, opioid antagonists substantially increase the density of ...

Mu-opioid receptor activation underpins clinical analgesia and is the central event in the abuse of narcotics. Continued opioid use produces tolerance to the acute effects of the drug and adaptations that lead to physical and psychological dependence. Continued mu-receptor signaling provides the engine for these adaptations, with most evidence suggesting that chronic agonist treatment produces ...

There is growing evidence that tonic activity of the opioid system may be important in the modulation of affective state. Naloxone produces a conditioned place aversion in rodents, an effect that is centrally mediated. Previous pharmacological data using antagonists with preferential actions at mu-, delta-, and kappa-opioid receptors indicate the importance of the mu-opioid receptor in mediatin...

Structural modification of salvinorin A, the active component of Salvia divinorum, has resulted in the synthesis of novel neoclerodane diterpenes with opioid receptor affinity and activity. We report in this study a nonnitrogenous neoclerodane diterpene with mu opioid receptor affinity (13) that is an agonist at mu opioid receptors. This represents the identification of a novel structural class...

Human mu opioid receptor gene polymorphisms and vulnerability to substance abuse. Sequence variations in the mu-opioid receptor gene (OPRM1) associated with human addiction to heroin. Sequence variability and candidate gene analysis in complex disease: association of mu opioid receptor gene variation with substance dependence. Mu opioid receptor gene variants: lack of association with alcohol d...

Activation by opioid receptors of cell proliferation was examined with fibroblast cell lines stably expressing either delta-opioid or mu-opioid receptors. Addition of [D-Ala2, D-Leu5]-enkephalin or [D-Pen2,D-Pen5]-enkephalin to Chinese hamster ovary (CHO) cells transfected with delta-opioid receptor cDNA resulted in an agonist concentration-dependent potentiation of fetal calf serum (FCS)-stimu...