European Neuropsychopharmacology (v.22, #10)

Contents (OBC).

Keywords: Schizophrenia; Neurotransmitter receptors; Mechanisms; Myelination; BDNF; SNCID;

Genetic polymorphisms in the opioid receptor mu1 gene are associated with changes in libido and insomnia in methadone maintenance patients by Sheng-Chang Wang; Hsiao-Hui Tsou; Chia-Hui Chen; Yu-Ting Chen; Ing-Kang Ho; Chin-Fu Hsiao; Sun-Yuan Chou; Yen-Feng Lin; Kai-Chi Fang; Chieh-Liang Huang; Lien-Wen Su; Yung-Chun Fang; Ming-Lun Liu; Hsiao-Yu Wu; Keh-Ming Lin; Shu Chih Liu; Hsiang-Wei Kuo; I-Chen Chiang; Andrew C.H. Chen; Jia-Ni Tian; Yu-Li Liu (695-703).
Methadone, a synthetic racemic opioid that primarily works as a μ-opioid receptor (OPRM1) agonist, is commonly used for the treatment of heroin addiction. Genetic association studies have reported that the OPRM1 gene is involved in the physiology of heroin and alcohol addiction. Our current study is designed to test the hypothesis that genetic polymorphisms in the OPRM1 gene region are associated with methadone dosage, plasma concentrations, treatment responses, adverse reactions and withdrawal symptoms in a methadone maintenance treatment (MMT) cohort from Taiwan. Fifteen OPRM1 single nucleotide polymorphisms (SNPs) were selected and genotyped using DNA samples from 366 MMT patients. The plasma concentrations of methadone and its metabolite were measured by high performance liquid chromatography. The results obtained using dominant model analysis indicate that the OPRM1 SNPs rs1074287, rs6912029, rs12209447, rs510769, rs3798676, rs7748401, rs495491, rs10457090, rs589046, rs3778152, rs563649, and rs2075572 are significantly associated with change-in-libido side effects (adjusted p < 0.042). Using recessive model analysis, these SNPs were also found to be significantly associated with insomnia side effects in this cohort (p < 0.009). The significance of the insomnia findings was mainly contributed by a subgroup of patients who had a positive urine morphine test (p < 0.022), and by individuals who did not use benzodiazepine hypnotics (p < 0.034). Our current data thus suggest that genetic polymorphisms in OPRM1 may influence the change-in-libido and insomnia side effects sometimes found in MMT patients.
Keywords: OPRM1; Methadone; Insomnia; Change-in-libido; TESS;

Alcohol consumption and premotor corpus callosum in older adults by Dimitrios Kapogiannis; Jason Kisser; Christos Davatzikos; Luigi Ferrucci; Jeffrey Metter; Susan M. Resnick (704-710).
Heavy alcohol consumption is toxic to the brain, especially to the frontal white matter (WM), but whether lesser amounts of alcohol negatively impact the brain WM is unclear. In this study, we examined the relationship between self-reported alcohol consumption and regional WM and grey matter (GM) volume in fifty-six men and thirty-seven women (70 + − 7 years) cognitively intact participants of the Baltimore Longitudinal Study of Aging (BLSA) with no history of alcohol abuse. We used regional analysis of volumes examined in normalized space (RAVENS) maps methodology for WM and GM segmentation and normalization followed by voxel based morphometry (VBM) implemented in SPM8 to examine the cross-sectional association between alcohol consumption and regional WM (and, separately, GM) volume controlling for age, sex, smoking, blood pressure and dietary thiamine intake. WM VBM revealed that in men, but not in women, higher alcohol consumption was associated with lower volume in premotor frontal corpus callosum. This finding suggests that even moderate amounts of alcohol may be detrimental to corpus callosum and white matter integrity.
Keywords: Alcohol; corpus callosum; premotor; white matter;

The relationship between prior antidepressant treatment and prefrontal brain functional response to subsequent treatment with antidepressant medication or placebo is unknown. Eighty-nine adults with Major Depressive Disorder (MDD), characterized as antidepressant-experienced or antidepressant-naive, received one week of single-blind placebo treatment prior to eight weeks of randomized treatment with medication (fluoxetine or venlafaxine; n = 47) or placebo (n = 42) in one of three similar placebo-controlled trials. Brain function was assessed at baseline, end of placebo lead-in, and during randomized treatment using quantitative electroencephalography (qEEG). The authors assessed change in prefrontal theta-band cordance (PFC) in antidepressant-experienced vs. antidepressant-naive subjects. Treatment history groups differed significantly on PFC change during the placebo lead-in even when controlling for clinical and demographic variables (F (1,62)  = 4.27, p = .04). As assessed in linear mixed models that examined treatment history (antidepressant-experienced or antidepressant-naive), treatment assignment (medication or placebo), and their interaction as predictors, treatment history also predicted PFC change during the randomized phase of treatment even when controlling for pretreatment clinical and demographic and symptom improvement during treatment (F (1,5o)  = 5.20, p = .03). The interaction was not significant. Post hoc analyses showed that antidepressant-experienced subjects treated with placebo showed PFC changes that did not differ from PFC changes seen in the medication group. Results suggest that prefrontal brain functional changes during treatment for MDD may differ depending upon prior treatment with antidepressant medication.
Keywords: Antidepressants; Prefrontal cortex; Electroencephalography; Placebo effect; Classical conditioning; Pharmacological biomarkers;

A double-blind, randomized, placebo-controlled study with JNJ-37822681, a novel, highly selective, fast dissociating D2 receptor antagonist in the treatment of acute exacerbation of schizophrenia by Mark E. Schmidt; Justine M. Kent; Ella Daly; Luc Janssens; Nancy Van Osselaer; Gitta Hüsken; Ion-George Anghelescu; Luc Van Nueten (721-733).
JNJ-37822681 is a novel, highly selective dopamine D2 receptor antagonist characterized by a rapid dissociation rate from the dopamine D2 receptor. This profile was hypothesized to confer antipsychotic efficacy and improved tolerability. In this 12-week study, the efficacy and safety of JNJ-37822681 were evaluated in patients with an acute exacerbation of schizophrenia, randomly assigned (1:1:1:1:1) to JNJ-37822681 (10-, 20- or 30-mg bid), olanzapine (15 mg once-daily), or placebo (for 6 weeks followed by olanzapine for 6 weeks). Of 498 randomized patients, 298 (60%) completed the study. All JNJ-37822681 dose groups and the olanzapine group showed significantly greater reduction in PANSS total score from baseline to week 6 versus placebo (all p-values < 0.001). Least-squares adjusted mean changes from baseline to week 6 in PANSS total score were: − 6.4 (placebo); − 18.4 (10 mg JNJ-37822681), − 17.7 (20 mg JNJ-37822681), − 20.0 (30 mg JNJ-37822681) and − 22.9 (olanzapine). All JNJ-37822681 groups showed significant improvement versus placebo from baseline to week 6 in the PANSS subscales, Marder factors, Clinical Global Impression of Severity, and in the Subjective Well-Being on Neuroleptics scale (all p-values < 0.05). The most common treatment-emergent adverse events with JNJ-37822681 were insomnia (17%) and akathisia (13%). Incidences of extrapyramidal symptoms were dose-related and were comparable for JNJ-37822681 10 mg bid and olanzapine groups. All JNJ-37822681 dose groups showed lesser weight gain compared with olanzapine. The efficacy and tolerability profile of the JNJ-37822681 10 mg bid was consistent with the study hypothesis.
Keywords: Antipsychotic agents; Dopamine antagonist; JNJ-37822681; Olanzapine; Schizophrenia;

Dexamphetamine reduces auditory P3 delta power and phase-locking while increasing gamma power by Matthew A. Albrecht; Greg Price; Joseph Lee; Rajan Iyyalol; Mathew T. Martin-Iverson (734-746).
Auditory P3 amplitude reduction is one of the most robust and replicated findings in schizophrenia. Recent evidence suggests that these reductions are due to reductions in both power and phase-locking at delta and theta frequencies. We have previously shown that the auditory, but not visual, P3 is reduced in healthy participants given the catecholamine releasing agent dexamphetamine. Our aim was to determine whether the auditory P3 amplitude reduction induced by dexamphetamine has similar power and phase locking characteristics to that seen in schizophrenia. Forty-four healthy participants were given 0.45 mg/kg dexamphetamine and placebo, in a double-blinded, placebo-controlled, cross-over design. The task was a three-stimulus auditory odd-ball task, target stimuli were the major stimuli of interest. Individual target trials underwent wavelet analysis to give power and phase-locking of delta (3 Hz), theta (4–7 Hz), alpha (8–12 Hz), beta (13–30 Hz) and gamma (30–50 Hz) frequencies for a 50 ms time window centred around the peak of the target P3. Delta power around the P3 peak was significantly reduced when participants were given dexamphetamine. Delta phase-locking was also reduced but only when analysis was targeted at the location of the peak P3 amplitude. In contrast, theta power and phase-locking were not affected by dexamphetamine. These findings suggest that increased catecholamine activity may be responsible for the power and phase-locking reductions of the auditory P3 delta component in patients with schizophrenia. Interestingly, dexamphetamine significantly increased gamma power around the P3 peak. We attempt to link this finding with the gamma alterations that have been found in patients with schizophrenia.
Keywords: Dopamine; Noradrenaline; Dexamphetamine; P300; Schizophrenia; Positive symptoms;

DAI-10 is as good as DAI-30 in schizophrenia by René Ernst Nielsen; Eva Lindström; Jimmi Nielsen; Sten Levander (747-750).
Drug attitude inventory (DAI-30) is considered to be the best predictor of poor adherence in first-episode schizophrenia. We compared the short version (DAI-10) with DAI-30 in long-term schizophrenia, documented if DAI was associated with poor insight, PANSS and GAF and constructed DAI-10 percentiles. DAI-30 and DAI-10 were homogenous (r = 0.82 and 0.72, respectively) with good test–retest reliability (0.79). The correlation between the DAI versions was high (0.94). Percentile scores of DAI-10 were computed. DAI is an easy-to-use self-report instrument seemingly assessing a unique clinical dimension relevant to non-adherence. DAI-10 might be preferred for its simplicity and good psychometric properties.
Keywords: Rating scales; Schizophrenia; Cognitive neuroscience; Insight; DAI;

Synergistic antidepressant-like action of gaboxadol and escitalopram by Trine Christensen; Cécile Bétry; Ouissame Mnie-Filali; Adeline Etievant; Bjarke Ebert; Nasser Haddjeri; Ove Wiborg (751-760).
According to current theories on the etiopathogenesis and pathophysiology of depression, both GABAergic and monoaminergic transmitter systems are perturbed. Consequently, the present study addressed the putative antidepressant action of the sedative-hypnotic GABAA receptor agonist, gaboxadol, separately and in combination with the selective serotonin reuptake inhibitor (SSRI) escitalopram. The rat chronic mild stress model was used to test the chronic antidepressant properties of gaboxadol in this depression model. Sucrose intake used as a read-out on anhedonic-like behavior indicated that the drug response rate for gaboxadol (5 mg/kg/day, i.p.) was similar to that measured for escitalopram (5 mg/kg/day, i.p.), however, the rate increased when the two drugs were co-administered, suggesting a synergistic action. Using in vivo electrophysiological recordings in dorsal raphe nucleus (DRN) of anesthetised rats, the present results showed that one week treatment with gaboxadol (5 mg/kg/day, i.p.) or with escitalopram (5 mg/kg/day, i.p.), followed by a 24 h washout period, did not affect DRN 5-HT neuronal firing per se, but in rats treated with both drugs for one week, the firing rate of DRN 5-HT neurons was significantly increased. Immunohistochemical estimations of cell proliferation in the hippocampal dentate gyrus did not reveal any effect of gaboxadol on chronic mild stressed rats, indicating that neurogenesis per se is not systematically associated with recovery from anhedonic-like behavior. Taken together, our data reveal for the first time an antidepressant action of gaboxadol and indicate a synergistic mechanism, regarding rapid onset of action and efficacy, when co-administered with escitalopram.
Keywords: Chronic mild stress; Serotonergic firing rates; Adult neurogenesis; Depression; Antidepressants;

Haloperidol, a dopamine (DA) D2 receptor-preferring antagonist, produces catalepsy whereby animals maintain awkward posture for a period of time. Sub-threshold doses of haloperidol fail to produce catalepsy initially, however, when the drug is given repeatedly in the same test environment, gradual day-to-day increases in catalepsy are observed. More importantly, if sensitized rats are injected with saline instead of haloperidol they continue to be cataleptic in the test environment suggesting that environment-drug associations may play a role. DA D3 receptors have been implicated in a number of conditioned behaviors. We were interested if DA D3 receptors contribute to catalepsy sensitization and conditioning in rats. We tested this hypothesis using the DA D3 receptor-selective antagonist NGB 2904 (0.5, 1.8 mg/kg) and the DA D3 receptor-preferring antagonist nafadotride (0.1, 0.5 mg/kg). For 10 consecutive conditioning days rats were treated with one of the D3 receptor antagonists alone or in combination with haloperidol (0.25 mg/kg) and tested for catalepsy, quantified by the time a rat remained with its forepaws on a horizontal bar. On test day (day 11), rats were injected with saline or the D3 receptor antagonist and tested for conditioned catalepsy in the previously drug-paired environment. Rats treated with NGB 2904 or nafadotride alone did not develop catalepsy. Rats treated with haloperidol or haloperidol plus NGB 2904 or nafadotride developed catalepsy sensitization with repeated conditioning. When injected with saline they continued to exhibit catalepsy in the test environment — now conditioned. On the other hand, NGB 2904 (1.8 mg/kg) or nafadotride (0.5 mg/kg) given on the test day (after sensitization to haloperidol) significantly attenuated the expression of conditioned catalepsy. Our data suggest that the D3 receptor antagonist NGB 2904 (1.8 mg/kg) and nafadotride (0.5 mg/kg) significantly attenuate conditioned catalepsy in rats when given in test but not when given during sensitization. Results implicate DA D3 receptors in regulating the expression of conditioned catalepsy.
Keywords: Context-dependency; Catalepsy; Sensitization; Dopamine D3 receptors; Conditioned catalepsy; Motivation;