Variation of the human mu-opioid receptor (OPRM1) gene predicts vulnerability to frustration

Opioid Receptor Mu 1 Gene (OPRM1) A118G Polymorphism and Emotional Modulation of Pain

Purpose

The A118G polymorphism in the opioid receptor mu 1 gene (OPRM1) is associated with decreased opioid receptor availability, altered emotion, and increased pain. Given that emotions modulate pain (positive emotions inhibit pain, negative emotions enhance pain), we predicted that G allele carriers would experience impaired emotional modulation of pain compared to non-G allele carriers.

Patients and Methods

Emotional pictures (ie, erotica, neutral, attack) from the International Affective Picture System were used by permission from the authors to experimentally manipulate emotions in 64 adult participants while painful electrocutaneous stimulations were delivered in a cross-sectional study. Ratings of arousal and valence/pleasure were made in response to pictures, and pain ratings and a physiological measure of spinal nociception (ie, nociceptive flexion reflex, NFR) were collected in response to painful stimulations. Secondary analyses were conducted to examine the relationship between the A118G polymorphism and emotional modulation of pain/NFR.

Results

Exposure to emotional pictures elicited similar changes in valence, but G-carriers rated erotic pictures as more arousing. In non-carriers, pain was facilitated by attack pictures and pain and NFR were inhibited by erotic pictures relative to neutral pictures. Among G-carriers, pain was facilitated by negative emotional pictures but there was no pain or NFR inhibition by positive emotional pictures.

Conclusion

The altered response to pleasant stimuli further supports the role of opioids in appetitive behavior and describes how the A118G polymorphism may prevent carriers from inhibiting pain during pleasure.

The First Exploratory Personalized Medicine Approach to Improve Bariatric Surgery Outcomes Utilizing Psychosocial and Genetic Risk Assessments: Encouraging Clinical Research

It is predicted that by 2030, globally, an estimated 2.16 billion adults will be overweight, and 1.12 billion will be obese. This study examined genetic data regarding Reward Deficiency Syndrome (RDS) to evaluate their usefulness in counselling patients undergoing bariatric surgery and gathered preliminary data on the potential use in predicting short term (6-month) weight loss outcomes. Methods: Patients undergoing bariatric surgery (n = 34) were examined for Genetic Addiction Risk Severity (GARS) [measures the presence of risk alleles associated with RDS]; as well as their psychosocial traits (questionnaires). BMI changes and sociodemographic data were abstracted from Electronic Health Records. Results: Subjects showed ∆BMI (M = 10.0 ± 1.05 kg/m2) and a mean % excess weight loss (56 ± 13.8%). In addition, 76% of subjects had GARS scores above seven. The homozygote risk alleles for MAO (rs768062321) and DRD1 (rs4532) showed a 38% and 47% prevalence among the subjects. Of the 11 risk alleles identified by GARS, the DRD4 risk allele (rs1800955), was significantly correlated with change in weight and BMI six months post-surgery. We identified correlations with individual risk alleles and psychosocial trait scores. The COMT risk allele (rs4680) showed a negative correlation with EEI scores (r = -0.4983, p < 0.05) and PSQI scores (r = -0.5482, p < 0.05). The GABRB3 risk allele (rs764926719) correlated positively with EEI (r = 0.6161, p < 0.01) and FCQ scores (r = 0.6373, p < 0.01). The OPRM1 risk allele showed a positive correlation with the DERS score (r = 0.5228, p < 0.05). We also identified correlations between DERS and BMI change (r = 0.61; p < 0.01). Conclusions: These data support the potential benefit of a personalized medicinal approach inclusive of genetic testing and psychosocial trait questionnaires when counselling patients with obesity considering bariatric surgery. Future research will explore epigenetic factors that contribute to outcomes of bariatric surgery.

The interplay between parental care and OPRM1 in reward responsiveness

The Reinforcement Sensitivity Theory (RST) explains a variety of reward-motivated behaviors as the result of the activation of biologically-based systems. Inspired by the influences of parental bonding and opioid peptide on reward system, we investigated the contributions of parental bonding and mu-opioid receptor gene (OPRM1) towards motivation systems (i.e., the BAS, BIS-anxiety, and FFFS-fear). Results indicated that (1) parental care was negatively related to FFFS-fear, but parental overprotection was positively related to both FFFS-fear and BIS-anxiety; (2) parental care significantly interacted with OPRM1 rs1799971 in reward responsiveness with diathesis-stress model. Poor parental care reduced reward responsiveness among individuals with the G allele, but not those with the AA genotype. These findings from this study demonstrate a new gene-environment interactive mechanism of the RST.

Endogenous opiates and behavior: 2020

This paper is the forty-third consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2020 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

The Molecular Basis of Resilience: A Narrative Review

Resilience refers to the adaptability of a person - an ability to "bounce-back" from stressors. We question if resilience can be strengthened, potentially to decrease the risk of stress-related disorders. Unfortunately, the molecular origins of resilience are complicated and not yet well understood. In this review, we examine the various physiological biomarkers of resilience, including the associated genes, epigenetic changes, and protein biomarkers associated with resilient phenotypes. In addition to assessing biomarkers that may indicate higher levels of resilience, we also review at length the many biomarkers that confer lower levels of resilience and may lead to disorders of low resilience, such as anxiety and depression. This large and encompassing review may help to identify the possible therapeutic targets of resilience. Hopefully these studies will lead to a future where stress-related disorders can be prevented, rather than treated.