Endogenous morphine-6-glucuronide (M6G) is present in the plasma of patients: validation of a specific anti-M6G antibody for clinical and basic research

Revealing the Kinetic Advantage of a Competitive Small-Molecule Immunoassay by Direct Detection

Small-molecule detection in an immunoassay format generally employs competition or labeling. A novel direct-detection label-free primary immunoassay utilizing second harmonic generation (SHG) has been developed and the utility of the method has been demonstrated for several small-molecule narcotics. Specifically, the binding of morphine, methadone, and cocaine to antimorphine, antimethadone, and anticocaine antibodies was measured by SHG, allowing binding affinities and rates of dissociation to be obtained. The SHG primary immunoassay has provided the first kinetic measurements of small-molecule hapten interactions with a receptor antibody. The kinetics reveal for the first time that competitive immunoassays achieve their selectivity by taking advantage of the kinetics of association and dissociation of the labeled and unlabeled target and nontarget small-molecule to the capture antibody. In particular, the induced fit of the target small-molecule to their antibody pairs prolongs their residence time, while the nontarget small-molecule dissociate rapidly in comparison.

Simultaneous analysis of gemfibrozil, morphine, and its two active metabolites in different mouse brain structures using solid-phase extraction with ultra-high performance liquid chromatography and tandem mass spectrometry with a deuterated internal standard

A rapid and sensitive bioassay was established and validated to simultaneously determine gemfibrozil, morphine, morphine-3β-glucuronide, and morphine-6β-glucuronide in mouse cerebrum, epencephalon, and hippocampus based on ultra-high performance liquid chromatography and tandem mass spectrometry. The deuterated internal standard, M6G-d3, was mixed with the prepared samples at 10 ng/mL as the final concentration. The samples were transferred into the C18 solid-phase extraction columns with gradient elution for solid-phase extraction. The mobile phase consisted of methanol and 0.05% formic acid (pH 3.2). Multiple reaction monitoring has been applied to analyze gemfibrozil (m/z 249.0 → 121.0) in anion mode, and M6G-d3 (m/z 465.1 → 289.1), morphine (m/z 286.0 → 200.9), and M3G and M6G (m/z 462.1 → 286.1) in the positive ion mode. The method has a linear calibration range from 0.05 to 10 ng for gemfibrozil, morphine, and M3G and M6G with correlation coefficients >0.993. The lower limit of quantitation for all four analytes was 0.05 ng/mL, relative standard deviation of intra- and interday precision was less than 10.5%, and the relative error of accuracy was from -8.2 to 8.3% at low, medium, and high concentrations for all the analytes. In conclusion, gemfibrozil can influence the morphine antinociception after coronary heart disease induced chronic angina by the change in one of morphine metabolites', M3G, distribution in mouse brain.

Endogenous opiates and behavior: 2014

This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants). This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants).