The high-affinity binding of benzomorphan drugs (ethylketocyclazocine and N-allylnorcyclazocine) and [DAla2,DLeu5] enkephalin was examined in a mouse neuroblastoma--Chinese hamster brain clonal hybrid cell line (NCB-20). Scatchard analysis of saturation binding isotherms indicated the presence of a single binding site for 3H-labeled [DAla2,DLeu5]enkephalin (Kd = 3 nM) and multiple binding sites...

BACKGROUND AND THE PURPOSE OF THE STUDY The aim of the present study was to examine factors that may influence the protein binding of morphine 6-glucuronide (M6G), the most active metabolite of morphine. METHODS An enzyme-linked immunoabsorbent assay technique was used to measure the M6G concentration in serum of 18 healthy adults, 18 neonatal and 7 children with cancer. Total and free M6G co...

AIMS Pain depresses expression of many behaviors, and one goal of analgesic treatment is to restore pain-depressed behaviors. Assays that focus on pain-depressed behaviors may contribute to preclinical assessment of candidate analgesics. MAIN METHODS This study compared effects of the mu opioid receptor agonist morphine (an acknowledged analgesic), the dopamine receptor antagonist haloperidol...

Agonists at the µ-opioid receptor are known to produce potent analgesic responses in the clinical setting, therefore, an increased understanding of the molecular interactions of ligands at this receptor could lead to improved analgesics. As historically morphine has been shown to be a poor recruiter of β-arrestin in recombinant cell systems and this can be overcome by the co-expression of GRK2,...

Overseas investigations have shown that many healthcare institutions are understocked of antidotes to treat these patients. 1–4 Despite a recent study to the contrary, 5 the paper by Fountain and colleagues, published in this issue of the New Zealand Medical Journal, suggests similar problems in New Zealand hospitals with shortcomings in hospital pharmacy stocks and resupply. 6 The paper raises...

Pain is associated with stimulation of some behaviors and depression of others, and μ-opioid receptor agonists are among the most widely used analgesics. This study used parallel assays of pain-stimulated and pain-depressed behavior in male Sprague-Dawley rats to compare antinociception profiles for six μ-agonists that varied in efficacy at μ-opioid receptors (from highest to lowest: methadone,...

The influence of sex in determining responses to opioid analgesics has been well established in rodents and monkeys in assays of short-lasting, phasic pain. The purpose of this investigation was to use a capsaicin model of tonic pain to evaluate sex differences in hyperalgesia and mu-opioid-induced antihyperalgesia in Fischer 344 (F344) rats. Capsaicin injected into the tail produced a dose-dep...

BACKGROUND Opioid analgesics are the most effective drugs for the treatment of moderate to severe pain. However, they also produce several adverse effects that can complicate pain management. The μ opioid (MOP) receptor, a G protein-coupled receptor, is recognized as the opioid receptor type which primarily mediates the pharmacological actions of clinically used opioid agonists. The morphinan c...

Mu-opioid analgesics are a mainstay in the treatment of acute and chronic pain of multiple origins, but their side effects, such as constipation, respiratory depression, and abuse liability, adversely affect patients. The recent demonstration of the up-regulation and membrane targeting of the delta-opioid receptor (DOR) following inflammation and the consequent enhanced therapeutic effect of de...

Pain is associated with stimulation of some behaviors and depression of others, and m-opioid receptor agonists are among the most widely used analgesics. This study used parallel assays of pain-stimulated and pain-depressed behavior in male SpragueDawley rats to compare antinociception profiles for six m-agonists that varied in efficacy at m-opioid receptors (from highest to lowest: methadone, ...