Detection of single nucleotide polymorphisms of the human mu opioid receptor gene by hybridization or single nucleotide extension on custom oligonucleotide gelpad microchips: Potential in studies of addiction

Abstract

The human mu opioid receptor (MOR) plays a central role in mediating the effects of opioids, both endogenous and exogenous. Epidemiological studies have shown that addiction in general, and especially opiate addiction, has a heritable component. Clinical and laboratory studies suggest that the MOR gene may contribute to the heritable component of vulnerability to develop opiate addiction. Naturally occurring single nucleotide polymorphisms (SNPs) have been identified in the MOR gene by conventional methods. Two coding region SNPs, the A118G and C17T substitutions, occur at high allelic frequencies (10.5% and 6.6%, respectively, in our previous studies). These common SNPs cause amino acid changes in the receptor, and may have implications for differences in individual responses to opioids, as well as decreased or increased vulnerability to opiate addiction. The A118G substitution encodes a variant receptor with binding and signal transduction differences in response to beta-endorphin in cellular assays. Recent innovations in microchip technology offer new potential methods for SNP detection. We report here on the development of two separate approaches using custom oligonucleotide gelpad microarrays for detection of these two common SNPs of the MOR gene in human DNA samples. First, PCR-amplified genomic DNA samples were used to produce target sequences, which were labeled with fluorescent dye and hybridized to custom microchips. Oligonucleotides on these reusable microchips were designed to query nucleotide substitutions at positions 17 and 118 of the MOR gene. Thirty-six human DNA samples were assayed both on these custom microchips and by conventional automated gel sequencing, with highly concordant identification of both heterozygous and homozygous substitutions. A second approach was developed for the C17T SNP utilizing single nucleotide extension on custom microchips. These custom gelpad microchips have potential for the rapid and inexpensive detection of specific SNPs for genetic and genomic studies.

Epigenetic Changes Induced by Exercise

“…Finally Galanter et al [85] reported that patients more oriented toward a spiritual than a formerly religious affiliation toward other 12-step members (a spiritual awakening) associated with lower rates of substance seeking behavior. Evidence continues to emerge regarding our understanding of brain function especially the reward circuitry and all addictive behaviors and clinicians are encouraged to review some of the select molecular neurogenetic literature [86][87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105].…”

Hypothalamic-Pituitary-Adrenocortical (HPA) Axis Response and Biotransformation of Oral Naltrexone Preliminary Examination of Relationship to Family History of Alcoholism

“…It will also be of interest in future studies to determine whether any differences in response to oral naltrexone, such as those alluded to in this report with FHϩ persons, might be related to the presence of a heterozygous or homozygous state with respect to a very common allelic variant of the -opioid receptor gene A118G. This variant has been found by our group, in collaboration with the group of Dr. Lei Yu, to have both significantly greater binding and functional responses to the longest endogenous opioid, ␤-endorphin, than does the prototype or usual gene product (Bond et al 1998;Kreek 2000;LaForge et al 2000).…”

Novel Microarray Design Strategy To Study Complex Bacterial Communities

“…The design of oligonucleotide probes appears to be mandatory for resolving punctual sequence differences compared to PCR products that have been shown to exhibit poor performance for single-nucleotide polymorphism or punctual mutation analysis (19,27,29,38). Moreover, oligonucleotide probes are more flexible and can be tailored to meet critical criteria such as sequence specificity and physicochemical properties.…”