A6V polymorphism of the human μ-opioid receptor decreases signalling of morphine and endogenous opioids in vitro.

Background And Purpose: Polymorphisms of the μ opioid receptor (MOPr) may contribute to the variation in responses to opioid drugs in clinical and unregulated situations. The A6V variant of MOPr (MOPr-A6V) is present in up to 20% of individuals in some populations, and may be associated with heightened susceptibility to drug abuse. There are no functional studies examining the acute signalling of MOPr-A6V in vitro, so we investigated potential functional differences between MOPr and MOPr-A6V at several signalling pathways using structurally distinct opioid ligands.

Fluorescence-based, high-throughput assays for μ-opioid receptor activation using a membrane potential-sensitive dye.

The development of new and improved opioid analgesics requires high-throughput screening (HTS) methods to identify potential therapeutics from large libraries of lead compounds. Here we describe two simple, real-time fluorescence-based assays of μ-opioid receptor activation that may be scaled up for HTS. In AtT-20 cells expressing the μ-opioid receptor (MOPr), opioids activate endogenous G protein gated inwardly rectifying K channels (GIRK channels), leading to membrane hyperpolarization.

Buprenorphine signalling is compromised at the N40D polymorphism of the human μ opioid receptor in vitro.

Background And Purpose: There is significant variation in individual response to opioid drugs, which may result in inappropriate opioid therapy. Polymorphisms of the μ opioid receptor (MOP receptor) may contribute to individual variation in opioid response by affecting receptor function, and the effect may be ligand-specific. We sought to determine functional differences in MOP receptor signalling at several signalling pathways using a range of structurally distinct opioid ligands in cells expressing wild-type MOP receptors (MOPr-WT) and the commonly occurring MOP receptor variant, N40D.

Cellular signalling of non-synonymous single-nucleotide polymorphisms of the human μ-opioid receptor (OPRM1).

Unlabelled: There is significant variability in individual responses to opioid drugs, which is likely to have a significant genetic component. A number of non-synonymous single-nucleotide polymorphisms (SNPs) in the coding regions of the μ-opioid receptor gene (OPRM1) have been postulated to contribute to this variability. Although many studies have investigated the clinical influences of these μ-opioid receptor variants, the outcomes are reported in the context of thousands of other genes and environmental factors, and we are no closer to being able to predict individual response to opioids based on genotype.

A real-time, fluorescence-based assay for measuring μ-opioid receptor modulation of adenylyl cyclase activity in Chinese hamster ovary cells.

Inhibition of adenylyl cyclase (AC) activity is frequently used to measure µ-opioid receptor (MOR) activation. We sought to develop a simple, rapid assay of AC activity in whole cells that could be used to study MOR signaling. Chinese hamster ovary cells expressing human MOR (CHO-MOR cells) were grown in 96-well plates and loaded with membrane potential-sensitive fluorescent dye.

A continuous, fluorescence-based assay of μ-opioid receptor activation in AtT-20 cells.

Opioids are widely prescribed analgesics, but their use is limited due to development of tolerance and addiction, as well as high variability in individual response. The development of improved opioid analgesics requires high-throughput functional assays to assess large numbers of potential opioid ligands. In this study, we assessed the ability of a proprietary "no-wash" fluorescent membrane potential dye to act as a reporter of µ-opioid receptor (MOR) activation and desensitization via activation of G-protein-coupled inwardly rectifying potassium channels.

14q12 microdeletions excluding FOXG1 give rise to a congenital variant Rett syndrome-like phenotype.

Rett syndrome is a clinically defined neurodevelopmental disorder almost exclusively affecting females. Usually sporadic, Rett syndrome is caused by mutations in the X-linked MECP2 gene in ∼90-95% of classic cases and 40-60% of individuals with atypical Rett syndrome. Mutations in the CDKL5 gene have been associated with the early-onset seizure variant of Rett syndrome and mutations in FOXG1 have been associated with the congenital Rett syndrome variant.