Association of dopamine receptor gene polymorphism and psychological personality traits in liability for opioid addiction

Initial Study on COMT and DRD2 Gene Polymorphisms as Well as the Influence of Temperament and Character Trait on the Severity of Alcohol Craving in Alcohol-Dependent Patients

The main aim of this work was to determine the impact of COMT and DRD2 gene polymorphisms together with temperament and character traits on alcohol craving severity alcohol-dependent persons. The sample comprised of 89 men and 16 women (aged 38±7). For the sake of psychological assessment various analytic methods have been applied like the Short Alcohol Dependence Data Questionnaire (SADD), Penn Alcohol Craving Scale (PACS) or Temperament and Character Inventory (TCI) test. The SNP polymorphism of the analyzed genes was determined by Real Time PCR test. The results showed, that the COMT polymorphismmay have an indirected relationship with the intensity and changes in alcohol craving during abstinence. The DRD2 receptor gene polymorphisms are related with the intensity of alcohol craving. It seems that the character traits like “self-targeting”, including “self-acceptance”, are more closely related to the severity of alcohol craving and polymorphic changes in the DRD2 receptor than temperamental traits. Although this is a pilot study the obtained results appeared to be promising and clearly indicate the link betweengene polymorphisms alcohol craving and its severity.

Behavioral Changes and Neuronal Damage in Rhesus Monkeys after 10 Weeks of Ketamine Administration Involve Prefrontal Cortex Dopamine D2 Receptor and Dopamine Transporter

The dopamine D2 receptor (DRD2) and dopamine transporter (DAT) play a regulatory role in dopaminergic neurotransmission and thus play an important role in drug addiction. The prefrontal cortex (PFC), a critical part of the mesencephalic dopaminergic system, is thought to be involved in the development and maintenance of drug addiction. The addiction to ketamine is thought to induce behavioral effects primarily through actions on the central nervous system. However, the neural mechanism underlying the effects of ketamine addiction remains unclear. In this study, we investigate the involvement of PFC DRD2 and DAT in ketamine addiction effects after ketamine administration for 10 weeks in nonhuman primates. To this end, after administering ketamine to rhesus monkeys for 10 weeks, we assessed changes in body weight and behavior. Additionally, neuronal changes in the PFC were examined by hematoxylin and eosin (HE) staining; the DRD2 and DAT mRNA and protein expression levels in the PFC were determined by real-time PCR and Western blot analysis, respectively. After 10-week ketamine administration, the assessment of the manifestations of toxicity in rhesus monkeys revealed significant changes in body weight and behavior, decreased DRD2 and DAT mRNA and protein expression in the PFC, and histological abnormalities including neuronal eosinophilia, pyknosis and disorderly arrangement of neurons in the PFC. These results suggest that the reduced expression of DRD2 and DAT in PFC could be involved in the behavioral and the neurological changes induced by ketamine administration, which may play an important role in the molecular mechanisms of ketamine addiction.

Association between DRD2/ANKK1 TaqIA polymorphism and common illicit drug dependence: evidence from a meta-analysis

BACKGROUND

Growing evidence indicated conflicting results about the dopamine receptor D2 (DRD2)/kinase domain containing 1 gene (ANKK1) TaqIA single nucleotide polymorphism (rs1800497) and common illicit drug dependence risk including stimulants, opioid and marijuana. We conducted a meta-analysis to evaluate the association between the polymorphism and common illicit drug dependence risk.

METHOD

A total of 25 available studies (26 subgroups) testing the association between the polymorphism and common illicit drug dependence were examined through Oct 2013. Pooled odds ratios (ORs) and 95% confidence intervals (CI) were estimated using fixed- and random-effects models when appropriate. Heterogeneity and publication bias were evaluated.

RESULTS

We found the DRD2/ANKK1 TaqIA polymorphism was significantly associated with increased risk of opioid dependence under homozygote, dominant, and recessive genetic model, respectively (homozygote: OR=1.546, 95%CI=1.279-1.87; dominant: OR=1.265, 95%CI=1.055-1.516; recessive: OR=1.409, 95%CI=1.182-1.680). Subgroup analyses were similar to the results of the total population by ethnicity and quality score. Besides, we also found that Caucasian and low-quality studies were major sources of heterogeneity for opioid dependence. We failed to find any significant association between the polymorphism and stimulants or marijuana neither in total population nor subgroup analyses under any genetic model.

CONCLUSIONS

The current meta-analysis suggested that DRD2/ANKK1 TaqIA polymorphism might be associated with opioid dependence risk, but not associated with stimulants or marijuana dependence.

Endogenous opiates and behavior: 2013

This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 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, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.