RETN gene polymorphisms interact with alcohol dependence in association with depression.

BACKGROUND: Previous studies suggest that alcohol dependence is associated with increased risk of depression. The occurrence of depressive symptoms is related to polymorphisms in various genetic regions. This study aimed to investigate the interaction of RETN gene polymorphisms (rs1477341, rs3745368) with alcohol dependence on depressive symptoms in adult male during acute alcohol withdrawal. METHODS: A total of 429 male adults were recruited in this study. Alcohol dependence was assessed using the Michigan alcoholism screening test (MAST). Depression was assessed using the 20-item self-rating depression scale (SDS). Hierarchical regression analysis was used to evaluate the interaction between genes and alcohol dependence on depression. Region of significance (ROS) test was used to explain the interaction effect. The strong and weak forms of the differential susceptibility and diathesis models were used to determine which fits the data better. RESULTS: Our results showed that MAST scores were significantly positively associated with SDS scores (r = 0.23, p < 0.01) in alcohol-dependent patients during alcohol withdrawal. The interaction between genotype and alcohol dependence was significant (ß = -0.14, p < 0.05) in a strong diathesis-stress model. Susceptibility for depression symptoms was associated with alcohol dependence in RETN rs1477341 A carriers. Specifically, those that showed more alcohol dependence and the A allele of RETN rs1477341 exhibited more depression symptoms. However, RETN rs3745368 had no significant interaction with alcohol dependence. CONCLUSIONS: The A allele of RETN rs1477341 may correlate with susceptibility to depression symptoms in alcohol-dependent individuals during acute alcohol withdrawal.

Impulsivity and aggression in alcohol withdrawal syndrome is modulated by the interaction of ZNF804A and mTOR polymorphism.

Alcohol withdrawal syndrome (AWS) is a poorly studied phenotype of alcohol use disorder. Understanding the relationship between allelic interactions and AWS-related impulsivity and aggression could have significant implications. This study aimed to investigate the main and interacting effects of ZNF804A and mTOR on impulsivity and aggression during alcohol withdrawal. 446 Chinese Han adult males with alcohol dependence were included in the study. Impulsivity and aggression were assessed, and genomic DNA was genotyped. Single gene analysis showed that ZNF804A rs1344706 (A allele/CC homozygote) and mTOR rs1057079 (C allele/TT homozygote) were strongly associated with AWS-related impulsivity and aggression. In the allelic group, MANOVA revealed a significant gene x gene interaction, suggesting that risk varied systematically depending on both ZNF804A and mTOR alleles. Additionally, a significant interactive effect of ZNF804A rs1344706 and mTOR rs7525957 was found on motor impulsivity and physical aggression, and the ZNF804A rs1344706 gene variant had significant effects on motor impulsivity and physical aggression only in mTOR rs7525957 TT homozygous carriers. The study showed that specific allelic combinations of ZNF804A and mTOR may have protective or risk-enhancing effects on AWS-related impulsivity and aggression.

The involvement of spontaneous brain activity in natural recovery from internet gaming disorder: A resting-state fMRI study.

Objective: Internet gaming disorder (IGD) can seriously impair an individual's physical and mental health. However, unlike the majority of those suffering from substance addiction, individuals with IGD may recover without any professional intervention. Understanding the brain mechanisms of natural recovery from IGD may provide new insight into how to prevent addiction and implement more targeted interventions. Methods: Sixty individuals with IGD were scanned by using a resting-state fMRI to assess brain region changes associated with IGD. After 1 year, 19 individuals with IGD no longer met the IGD criteria and were considered recovered (RE-IGD), 23 individuals still met the IGD criteria (PER-IGD), and 18 individuals left the study. The brain activity in resting state between 19 RE-IGD individuals and 23 PER-IGD individuals was compared by using regional homogeneity (ReHo). Additionally, brain structure and cue-craving functional MRIs were collected to further support the results in the resting-state. Results: The resting-state fMRI results revealed that activity in brain regions responsible for reward and inhibitory control [including the orbitofrontal cortex (OFC), the precuneus and the dorsolateral prefrontal cortex (DLPFC)] was decreased in the PER-IGD individuals compared to RE-IGD individuals. In addition, significant positive correlations were found between mean ReHo values in the precuneus and self-reported craving scores for gaming, whether among the PER-IGD individuals or the RE-IGD individuals. Furthermore, we found similar results in that brain structure and cue-craving differences exist between the PER-IGD individuals and RE-IGD individuals, specifically in the brain regions associated with reward processing and inhibitory control (including the DLPFC, anterior cingulate gyrus, insula, OFC, precuneus, and superior frontal gyrus). Conclusion: These findings indicate that the brain regions responsible for reward processing and inhibitory control are different in PER-IGD individuals, which may have consequences on natural recovery. Our present study provides neuroimaging evidence that spontaneous brain activity may influence natural recovery from IGD.

Acute and chronic ethanol administration: A potential model of behavioral sensitization using wheel-running in male CD1 mice.

RATIONALE: We define behavioral sensitization as an augmented response to subsequent dosing after chronic intermittent administration of a drug. However, the biphasic effects of ethanol (EtOH), first stimulatory followed by depressive, make animal models of behavioral sensitization rare. OBJECTIVES: This study aimed to determine a dose of EtOH that did not depress wheel-running (WR) in CD1 mice and then to develop a model of EtOH-induced behavioral sensitization. METHODS: For the first part of this study, male CD1 mice (n = 24, 6/group) were administered either phosphate buffer saline (PBS), 0.5 g/kg, 1 g/kg, or 2 g/kg EtOH at a volume of 3 ml/kg, intraperitoneally (IP). Mice were divided into equal groups and received the weight-based dose once daily on Days 1, 2, 3, 4, and 5. All mice received a challenge dose of 0.5 g/kg on Day 10. In both parts of the study, mice were habituated to the running wheel for 5 min prior to dosing and wheel running was measured for 10 min after each dose. RESULTS: The acute dose-response of EtOH effects on wheel running determined a significant difference between doses in wheel running (p < 0.05), with a post-hoc analysis establishing that 0.5 g/kg EtOH resulted in significantly more WR compared to 2 g/kg EtOH (p < 0.05). The chronic study demonstrated a significant main effect of Day (1 vs. 5 vs. Challenge, p < 0.001) and an interaction between Day and Treatment, with post-hoc analysis determining the effect to be between PBS and EtOH WR on Day 5 (p < 0.05). In addition, Bonferroni post-hoc analysis determined no differences between Days in the PBS condition, but a significant difference in the EtOH condition between Day 1 and Day 5 (p < 0.001) and that difference from Day 1 persisted when comparing to the Challenge Day (p < 0.01). CONCLUSION: After chronic, intermittent, low dose administration of EtOH, male mice showed an increase in activity as measured by wheel running. Therefore, we laid the groundwork for a potentially useful rodent model for EtOH-induced behavioral sensitization.

The Interaction Between POMC rs2071345 Polymorphism and Alcohol Dependence in Anxiety Symptoms Among Chinese Male Problem Drinkers.

Objective: Alcohol dependence can increase the level of anxiety. A growing body of research has identified a link between anxiety symptoms of problem drinkers and their genetic or environment factors, respectively. However, to date few studies have directly examined gene-environment (G × E) interaction on their anxiety symptoms during the acute alcohol withdrawal. The present study aims to examine the interaction between the proopiomelanocortin (POMC) rs2071345 polymorphism and alcohol dependence on anxiety symptoms of male problem drinkers, and further test the exact form of interaction on two competing models: the diathesis-stress model vs. the differential susceptibility model. Methods: A total of 440 male problem drinkers (M age = 44.5 years, SD = 9.45) were recruited from nine main psychiatric hospitals of northern China during acute alcohol withdrawal. Blood samples were collected for genotyping, self-reported anxiety symptoms, and levels of alcohol dependence were assessed. Results: Results indicated that the POMC rs2071345 polymorphism significantly moderated anxiety symptoms associated with alcohol dependence. A region of significance (RoS) test showed that male problem drinkers with T allele were more likely to experience more anxiety symptoms than those with CC homozygote when the standardized score of concurrent alcohol dependence was above 0.31. Confirmatory model evaluation indicated that the interaction effect involving POMC gene polymorphism conformed to the diathesis-stress model rather than differential-susceptibility model of person × environment interaction. Conclusions: This study suggested that the SNP in POMC rs2071345 was associated with alcohol dependence in anxiety symptoms of male problem drinkers and further provided evidence in support of the diathesis-stress hypothesis of alcohol dependence in terms of anxiety symptoms.

The Interaction Between Genetic Variant ZNF804A rs1344706 and Alcohol Withdrawal on Impulsivity: Evidence for the Diathesis-Stress Model.

Objective: Alcohol use disorder (AUD) is the most common substance use disorder, which may relate to increased impulsivity. A more detailed understanding of the potential moderating factor on association between AUD and impulsivity is likely to have far-reaching effects. This study aims to examine whether the interaction between a genetic variant ZNF804A rs1344706 and alcohol use is related to impulsivity in Chinese Han adult males diagnosed with AUD. Methods: A total of 455 Chinese Han adult males diagnosed with AUD were included in this study. Impulsivity was assessed using Barratt Impulsiveness Scale. Alcohol dependence was measured by Michigan Alcoholism Screening Test. Genomic DNA was extracted from peripheral blood of participants and genotyped. Results: Hierarchical multiple regression yielded a significant interaction between ZNF804A rs1344706 and alcohol use (ß = 0.20, p = 0.0237). Then, A region of significance (RoS) test was performed to interpret the interaction effect. Re-parameterized regression models revealed that the interaction between ZNF804A rs1344706 and alcohol problem severity fit to the weak diathesis-stress model (R 2 = 0.15, p < 0.0010), indicating that the T allele carriers are more susceptible to alcohol problem severity, jointly contributing to impulsivity. Conclusions: This study, which analyzed a specific gene-environment interaction, demonstrated that carriers of the T allele of ZNF804A rs1344706 may be more susceptible to alcohol problem severity, correlated with higher levels of impulsivity during withdrawal.

Trk: a neuromodulator of age-specific behavioral and neurochemical responses to cocaine in mice.

Responses to psychostimulants vary with age, but the molecular etiologies of these differences are largely unknown. The goal of the present research was to identify age-specific behavioral and molecular adaptations to cocaine and to elucidate the mechanisms involved therein. Postweanling, periadolescent, and adult male CD-1 mice were exposed to cocaine (20 mg/kg) for 7 d. The rewarding effects of cocaine were assessed, as were the response to a Trk antagonist and the regulation of dopamine and cAMP-regulated phosphoprotein, 32 kDa (DARPP-32). Cocaine was rewarding in both periadolescent and adult mice using a conditioned place preference procedure. In contrast, postweanling mice failed to demonstrate significant cocaine-induced place preference. Because components of the neurotrophin system including brain-derived neurotrophic factor and TrkB are developmentally regulated, their role in the age-specific effects of cocaine was determined using the Trk receptor antagonist K252a. Postweanling mice that received K252a before daily cocaine showed a significant place preference to the cocaine-paired environment that was not seen in the absence of K252a. DARPP-32 protein levels were significantly upregulated in the lateral region of the caudate-putamen exclusively in postweanling mice after chronic cocaine. Daily pretreatment with K252a attenuated the induction of DARPP-32 in the postweanling striatum. These data indicate that Trk neurotransmission plays a role in age-specific behavioral and molecular responses to cocaine and concurrently modulates DARPP-32 levels.

Exposure to the taste of alcohol elicits activation of the mesocorticolimbic neurocircuitry.

A growing number of imaging studies suggest that alcohol cues, mainly visual, elicit activation in mesocorticolimbic structures. Such findings are consistent with the growing recognition that these structures play an important role in the attribution of incentive salience and the pathophysiology of addiction. The present study investigated whether the presentation of alcohol taste cues can activate brain regions putatively involved in the acquisition and expression of incentive salience. Using functional magnetic resonance imaging, we recorded BOLD activity while delivering alcoholic tastes to 37 heavy drinking but otherwise healthy volunteers. The results yielded a pattern of BOLD activity in mesocorticolimbic structures (ie prefrontal cortex, striatum, ventral tegmental area/substantia nigra) relative to an appetitive control. Further analyses suggested strong connectivity between these structures during cue-elicited urge and demonstrated significant positive correlations with a measure of alcohol use problems (ie the Alcohol Use Disorders Identification Test). Thus, repeated exposure to the taste alcohol in the scanner elicits activation in mesocorticolimbic structures, and this activation is related to measures of urge and severity of alcohol problems.

Age-specific behavioral responses to psychostimulants in mice.

This study investigated the influence of age on the behavioral responses elicited by psychostimulants in male CD-1 mice. Behavioral activity including locomotion and stereotypy was measured following acute or repeated administration of cocaine, methylphenidate, amphetamine or saline to postweanling (24 days old), periadolescent (33 days old) and adult (60 days old) mice. Postweanling mice exhibited less total and ambulatory activity than periadolescent mice following a single acute injection of cocaine (20 or 30 and 30 mg/kg, respectively). Further, postweanling mice showed less total activity than both periadolescent and adult mice at a dose of 10 mg/kg methylphenidate. Less stereotypy was also seen in postweanling mice when compared to adolescent mice after 30 mg/kg amphetamine. Seven daily injections of cocaine resulted in a heightened behavioral response on day 7 as compared to day 1, indicative of behavioral sensitization in adult and periadolescent, but not postweanling mice. Repeated methylphenidate resulted in increased total activity in adult, but not periadolescent or postweanling mice. None of the animals were sensitized to the behavioral activating effects of amphetamine. The magnitude of behavioral response and the development of sensitization were dependent upon the age of the animal and the agent tested.

The distribution of cocaine in mice differs by age and strain.

Few studies have examined the influence of the age and the strain of mouse on the pharmacokinetics of psychostimulants, or the role of pharmacokinetics in age-related differences in drug responses. The present study compared concentrations of cocaine, and its metabolite, benzoylecgonine (BZE), in the blood and brain of early (P35) and later (P42) periadolescent and adult (P63) CD-1 and C57BL/6 male mice 15 min after acute intraperitoneal injection of cocaine (20 mg/kg). Brain levels of cocaine and BZE after seven daily cocaine injections in CD-1 and C57BL/6 mice beginning on P35 and on P63 were also measured. P35 periadolescents of both strains had lower blood cocaine levels than did the adults, but only C57BL/6 periadolescents had lower brain cocaine levels than the adults. C57BL/6 mice of both ages had higher blood cocaine levels than did the corresponding CD-1 mice. Concomitant with lower cocaine levels, periadolescent CD-1 mice had higher blood BZE levels than the adults, suggesting that periadolescents may metabolize cocaine faster. Brain cocaine levels in P42 C57BL/6 mice were similar to those of adults. Cocaine-induced activity did not differ between periadolescent and adult CD-1 mice after a single injection of cocaine, whereas periadolescent C57BL/6 mice had lower activity levels than did the adults after a single cocaine injection. Periadolescent CD-1 mice exhibited higher levels of locomotor activity following cocaine injection than did periadolescent C57BL/6 mice. Following chronic cocaine administration, cocaine and BZE levels in the brains of periadolescent and adult mice did not differ from each other in either strain. However, brain cocaine levels at both ages were lower in CD-1 mice than in C57BL/6 mice. In conclusion, the age and the strain of mouse significantly affect the levels of cocaine obtained in brain and blood following acute administration. Our data are consistent with the notion that CD-1 and C57BL/6 mice metabolize cocaine faster during the early periadolescent period than as adults. Furthermore, potentially important strain differences between CD-1 and C57BL/6 mice were noted in cocaine levels following acute and chronic cocaine administration, and in locomotor activity following acute cocaine administration.

The incentive salience of alcohol: translating the effects of genetic variant in CNR1.

CONTEXT: The gene that codes for cannabinoid receptor 1 (CNR1) represents an important target for investigations designed to elucidate individual differences in the etiology of alcohol dependence. OBJECTIVE: To achieve a better understanding of the role of the CNR1 gene in the etiology and treatment of alcohol dependence. DESIGN: The present investigation spans multiple levels of analysis, including receptor binding in postmortem brain tissue, neuroimaging, human laboratory models, and analyses of treatment outcome data. RESULTS: Findings indicate that the C allele of rs2023239 is associated with greater CB1 binding in the prefrontal cortex, greater alcohol cue-elicited brain activation in the midbrain and prefrontal cortex, greater subjective reward when consuming alcohol, and more positive outcomes after treatment with a medication that targets the mesocorticolimbic neurocircuitry. In addition, there were strong correlations between cue-elicited brain activation and alcohol consumption measures in individuals with the C allele. CONCLUSION: Individuals with the C allele may be more susceptible to changes in the mesocorticolimbic neurocircuitry that is involved in the attribution of incentive salience after repeated exposure to alcohol.

Cocaine alters mu but not delta or kappa opioid receptor-stimulated in situ [35S]GTPgammaS binding in rat brain.

Chronic cocaine administration produces alterations in mu and kappa opioid receptor density as well as striatal and accumbens opioid-regulated adenylyl cyclase activity, suggesting a psychostimulant responsive interaction between opioidergic and dopaminergic systems. Stimulation of G-protein-coupled opioid receptors inhibits adenylyl cyclase production of cyclic AMP. The present study employed in situ [(35)S]GTPgammaS binding to measure opioid receptor-stimulated activation of G-proteins in response to acute and chronic cocaine exposure. Male Fischer rats received acute (1 or 3 days) or chronic (14 days) binge pattern cocaine administration. Three and 14 days of cocaine injections resulted in greater increases in the ability of the mu receptor agonist DAMGO to stimulate [(35)S]GTPgammaS binding in both the core and the shell of the nucleus accumbens, all regions of the caudate putamen and the cingulate cortex compared with saline-matched controls. The greatest increases in DAMGO-stimulated [(35)S]GTPgammaS binding were observed in the dorsal areas of the caudate putamen in animals that received 14 days of cocaine. No significant changes in delta (DPDPE), or kappa (dynorphin A(1-17)) receptor-stimulated [(35)S]GTPgammaS binding were found in any brain region in response to cocaine administration. These results demonstrate that binge pattern cocaine administration induce changes in mu but not delta or kappa opioid receptor-mediated G-protein activity. This study provides support for the hypothesis that the addictive properties of both psychostimulants and opiates may share common neurochemical signaling substrates.