AMPA-type glutamate receptors have been suggested to be involved in the neurobiological mechanisms of drug addiction. We have made use of two mouse lines, which both have modulated AMPA receptor responses. The first line is entirely deficient in glutamate receptor-A (GluR-A) subunits (A-/- knock-out line) and, in the second one, the Q582 residue of GluR-A subunits is replaced by an arginine res...

Opioids produce antinociception, and ingested placenta or amniotic fluid modifies that antinociception. More specifically, ingested placenta enhances the antinociception produced by selective activation of central kappa-opioid or delta-opioid receptors but attenuates that produced by activation of central mu-opioid receptors. Opioids also slow gut transit by acting on central or peripheral mu-o...

Substantial evidence has been accumulated which suggests that opioid delta receptors may be distinguished on the basis of their involvement in the modulation (i.e., increase or decrease in potency) of mu-mediated antinociception. On this basis, it has been hypothesized that some opioid delta receptors exist within a functional complex with mu receptors (delta complexed (delta cx) receptors) whi...

We have previously shown that the naturally occurring levo-morphine at a subanalgesic picomolar dose pretreated i.t. induces antianalgesia against levo-morphine-produced antinociception. We now report that the synthetic stereo-enantiomer dextro-morphine, even at an extremely low femtomolar dose, induces antianalgesia against levo-morphine-produced antinociception using the tail-flick (TF) test ...

INTRODUCTION Previous studies have shown that the basolateral amygdale (BLA) is rich of CB1 cannabinoid receptors and involved in cannabinoid-induced antinociception. Also, it seems that there are functional interactions between the cannabinoid CB1 and opioid receptors in the process of sensitization to opiates. In the present study, we tried to examine the role of intra-BLA cannabinoid recepto...

mice were rendered tolerant and dependent to morphine by subcutaneous injection of morphine over a period of 5 days. the effects of acute and chronic administration of dihydropyridine calcium channel antagonist nifedipine on the development of tolerance and naloxone-precipitated morphine withdrawal signs were investigated. a single injection of nifedipine proved to be effective in inhibiting so...

BACKGROUND This study explores the underlying mechanism of the antiinflammatory effect of amitriptyline in chronic morphine-infused rats. METHODS Male Wistar rats were implanted with two intrathecal catheters. One catheter was for the continuous infusion of saline, amitriptyline (15 microg/h), morphine (15 microg/h), p38 mitogen-activated protein kinase inhibitor SB203580 (0.5 microg/h), morp...

Opioids are used to manage all types of pain including acute, cancer, chronic neuropathic and inflammatory pain. Unfortunately, opioid-related adverse effects such as respiratory depression, tolerance, physical dependence and addiction have led to an underutilization of these compounds for adequate pain relief. One strategy to improve the therapeutic utility of opioids is to co-administer them ...

introduction: the antinociceptive effect of morphine is, in part, mediated through the activation of a descending pathway. one of the major components of this pathway is the nucleus raphe magnus (nrm). our previous study demonstrated the involvement of nrm in the analgesic effect of morphine microinjected into the nucleus cuneiformis (ncf) in a descending manner. the aim of the current study wa...

Opioid receptors are currently classified as mu (mu: mOP), delta (delta: dOP), kappa (kappa: kOP) with a fourth related non-classical opioid receptor for nociceptin/orphainin FQ, NOP. Morphine is the current gold standard analgesic acting at MOP receptors but produces a range of variably troublesome side-effects, in particular tolerance. There is now good laboratory evidence to suggest that blo...