Despite mu opioid receptor agonists are the cornerstones of moderate-to-severe acute pain treatment, their effectiveness in chronic pain conditions is controversial. In contrast to mu opioid receptor agonists, a number of studies have reported the effectiveness of delta opioid receptor agonists on neuropathic pain strengthening the idea that delta opioid receptors gain importance when chronic p...

Inhibition of forebrain μ-opioid receptor signaling by low concentrations of rimonabant does not require cannabinoid receptors and directly involves μ-opioid receptors. Micromolar concentrations of rimonabant directly inhibits delta opioid receptor specific ligand binding and agonist-induced G-protein activity. receptor ligand with high in vitro and in vivo agonist efficacy.

The natural stilbene pawhuskin A has been shown to function as an opioid receptor antagonist, with preferential binding to the κ receptor. This finding encouraged assembly of a set of analogues to probe the importance of key structural features. Assays on these compounds determined that one (compound 29) shows potent opioid receptor binding activity and significantly improved selectivity for th...

Dynorphin A is an endogenous opioid peptide that activates the kappa opioid receptor (KOR) with high potency. Some studies also showed that the distribution and functional activity of dynorphin A are not completely correlated with those of KOR, suggesting that dynorphin A may interact with other receptors. To investigate the possibility that dynorphin A may serve as an agonist for other opioid ...

Opioid drugs such as heroin interact directly with opioid receptors whilst other addictive drugs, including marijuana, alcohol and nicotine indirectly activate endogenous opioid systems to contribute to their rewarding properties. The opioid system therefore plays a key role in addiction neurobiology and continues to be a primary focus for NIDA-supported research. Opioid receptors and their pep...

The aim of the study was to evaluate changes in the opioid receptor binding (mu, delta and kappa) in the hypothalamus, anterior pituitary and adrenal cortex (HPA) of lambs treated in vivo with corticotrophin releasing hormone (CRH), naltrexone, an opioid receptor antagonist (NAL), and dexamethasone, a potent cortisol analog (DEX). Experiment was carried out on 3 months old female lambs of polis...

Over the past several years substantial evidence has documented that opioid receptor homo- and heterodimers form in cell lines expressing one or more of the opioid receptors. We used opioid receptor knockout mice to determine whether in vivo pharmacological characteristics of kappa1 and kappa2 opioid receptors changed following knockout of specific opioid receptors. Using displacement of the ge...

chronic pain is a prevalent and debilitating condition, conveying immense human burden. suffering from chronic pain is not only caused by painful symptomatology, but also through a wide range of psychopathological and physical consequences, including depression and anxiety disorders, impaired sleep and cognition, cardiovascular morbidity and impaired sexual function, all contributing to diminis...

Opioids are widely prescribed pain relievers with multiple side effects and potential complications. They produce analgesia via G-protein-protein coupled receptors: μ-, δ-, κ-opioid and opioid receptor-like 1 receptors. Bivalent ligands targeted to the oligomerized opioid receptors might be the key to developing analgesics without undesired side effects and obtaining effective treatment for opi...

The mu opioid receptor system is altered in alcohol dependent (AD) subjects. Cortisol responses to opioid receptor antagonists are assumed to impart information about opioid receptor activity. In the present study we examined naloxone-induced cortisol responses in 18 healthy control (HC) and 25 recently detoxified AD subjects and then correlated the cortisol response with mu opioid receptor ava...