Molecular Psychiatry

Le Hellard, S; Mühleisen, T W; Djurovic, S; Fernø, J; Ouriaghi, Z; Mattheisen, M; Vasilescu, C; Raeder, M B; Hansen, T; Strohmaier, J; Georgi, A; Brockschmidt, F F; Melle, I; Nenadic, I; Sauer, H; Rietschel, M; Nöthen, M M; Werge, T; Andreassen, O A; Cichon, S; Steen, V M

doi: 10.1038/mp.2008.110pmid: 18936756

Several studies have reported structural brain abnormalities, decreased myelination and oligodendrocyte dysfunction in schizophrenia. In the central nervous system, glia-derived de novo synthesized cholesterol is essential for both myelination and synaptogenesis. Previously, we demonstrated in glial cell lines that antipsychotic drugs induce the expression of genes involved in cholesterol and fatty acids biosynthesis through activation of the sterol regulatory element binding protein (SREBP) transcription factors, encoded by the sterol regulatory element binding transcription factor 1 (SREBF1) and sterol regulatory element binding transcription factor 2 (SREBF2) genes. Considering the importance of these factors in the lipid biosynthesis and their possible involvement in antipsychotic drug effects, we hypothesized that genetic variants of SREBF1 and/or SREBF2 could affect schizophrenia susceptibility. We therefore conducted a HapMap-based association study in a large German sample, and identified association between schizophrenia and five markers in SREBF1 and five markers in SREBF2. Follow-up studies in two independent samples of Danish and Norwegian origin (part of the Scandinavian collaboration of psychiatric etiology study, SCOPE) replicated the association for the five SREBF1 markers and for two markers in SREBF2. A combined analysis of all samples resulted in highly significant genotypic P-values of 9 × 10−4 for SREBF1 (rs11868035, odd ration (OR)=1.26, 95% confidence interval (CI) (1.09–1.45)) and 4 × 10−5 for SREBF2 (rs1057217, OR=1.39, 95% CI (1.19–1.63)). This finding strengthens the hypothesis that SREBP-controlled cholesterol biosynthesis is involved in the etiology of schizophrenia.

Kato, M; Serretti, A

doi: 10.1038/mp.2008.116pmid: 18982004

This systematic review summarizes pharmacogenetic studies on antidepressant response and side effects. Out of the 17 genes we reviewed, 8 genes were entered into the meta-analysis (SLC6A4, HTR1A, HTR2A, TPH1, gene encoding the β-3 subunit, brain-derived neurotrophic factor (BDNF), HTR3A and HTR3B). TPH1 218C/C genotype (7 studies, 754 subjects) was significantly associated with a better response (odds ratio, OR=1.62; P=0.005) with no heterogeneity between ethnicities. A better response was also observed in subjects with the Met variant within the BDNF 66Val/Met polymorphism (4 studies, 490 subjects; OR=1.63, P=0.02). Variable number of tandem repeats polymorphism within intron 2 (STin2) 12/12 genotype showed a trend toward a better response in Asians (STin2: 5 studies, 686 subjects; OR=3.89, P=0.03). As for side effects, pooled ORs of serotonin transporter gene promoter polymorphism (5-HTTLPR) l (9 studies, 2642 subjects) and HTR2A −1438G/G (7 studies, 801 subjects) were associated with a significant risk modulation (OR=0.64, P=0.0005) and (OR=1.91, P=0.0006), respectively. Interestingly, this significance became more robust when analyzed with side effect induced by selective serotonin reuptake inhibitors only (5-HTTLPR: P=0.0001, HTR2A: P<0.0001). No significant result could be observed for the other variants. These results were not corrected for multiple testing in each variant, phenotype and subcategory. This would have required a Bonferroni significance level of P<0.0023. Although some heterogeneity was present across studies, our finding suggests that 5-HTTLPR, STin2, HTR1A, HTR2A, TPH1 and BDNF may modulate antidepressant response.

Banasr, M; Chowdhury, G M I; Terwilliger, R; Newton, S S; Duman, R S; Behar, K L; Sanacora, G

doi: 10.1038/mp.2008.106pmid: 18825147

Growing evidence indicates that glia pathology and amino-acid neurotransmitter system abnormalities contribute to the pathophysiology and possibly the pathogenesis of major depressive disorder. This study investigates changes in glial function occurring in the rat prefrontal cortex (PFC) after chronic unpredictable stress (CUS), a rodent model of depression. Furthermore, we analyzed the effects of riluzole, a Food and Drug Administration-approved drug for the treatment of amyotrophic laterosclerosis, known to modulate glutamate release and facilate glutamate uptake, on CUS-induced glial dysfunction and depressive-like behaviors. We provide the first experimental evidence that chronic stress impairs cortical glial function. Animals exposed to CUS and showing behavioral deficits in sucrose preference and active avoidance exhibited significant decreases in 13C-acetate metabolism reflecting glial cell metabolism, and glial fibrillary associated protein (GFAP) mRNA expression in the PFC. The cellular, metabolic and behavioral alterations induced by CUS were reversed and/or blocked by chronic treatment with the glutamate-modulating drug riluzole. The beneficial effects of riluzole on CUS-induced anhedonia and helplessness demonstrate the antidepressant action of riluzole in rodents. Riluzole treatment also reversed CUS-induced reductions in glial metabolism and GFAP mRNA expression. Our results are consistent with recent open-label clinical trials showing the drug's effect in mood and anxiety disorders. This study provides further validation of hypothesis that glial dysfunction and disrupted amino-acid neurotransmission contribute to the pathophysiology of depression and that modulation of glutamate metabolism, uptake and/or release represent viable targets for antidepressant drug development.

Raison, C L; Borisov, A S; Woolwine, B J; Massung, Breanne; Vogt, G; Miller, A H

doi: 10.1038/mp.2008.58pmid: 18521089

Interferon (IFN)-α has been used to investigate pathways by which innate immune cytokines influence the brain and behavior. Accordingly, the impact of IFN-α on diurnal secretion of hypothalamic–pituitary–adrenal (HPA) axis hormones was assessed in 33 patients eligible for treatment with IFN-α plus ribavirin for hepatitis C. In addition, the relationship between IFN-α-induced HPA axis changes and proinflammatory cytokines and behavior was examined. Plasma ACTH and cortisol as well as tumor necrosis factor (TNF)-α, interleukin-6 and their soluble receptors, were measured hourly between 0900 and 2100 hours at baseline and following approximately 12 weeks of either no treatment (n=13) or treatment with IFN-α/ribavirin (n=20). Plasma IFN-α was also measured at each visit. Depression and fatigue were assessed using the Montgomery–Asberg depression rating scale and the multidimensional fatigue inventory. Compared to no treatment, IFN-α/ribavirin administration was associated with significant flattening of the diurnal ACTH and cortisol slope and increased evening plasma ACTH and cortisol concentrations. Flattening of the cortisol slope and increases in evening cortisol were correlated with increases in depression (r=0.38, P<0.05 and r=0.36, P<0.05, respectively) and fatigue (r=0.43, P<0.05 and r=0.49, P<0.01, respectively). No relationship was found between immune and HPA axis measures, although increases in plasma IFN-α, TNF-α and soluble TNF-α receptor2 were independently correlated with behavioral endpoints. These data indicate that chronic exposure to innate immune cytokines may contribute to the altered diurnal HPA axis activity and behavior found in medically ill individuals. However, given the lack of correlation between HPA axis and immune measures, the mechanism by which chronic cytokine exposure influences HPA axis function remains to be determined.

Lee, S S; Chronis-Tuscano, A; Keenan, K; Pelham, W E; Loney, J; Van Hulle, C A; Cook, E H; Lahey, B B

doi: 10.1038/mp.2008.102pmid: 18779819

Although maternal parenting is central to child development, little is known about the interplay between molecular genetic and environmental factors that influence parenting. We tested the association of the 40-bp variable number tandem repeat polymorphism of the dopamine transporter (DAT1; SLC6A3) gene with three dimensions of observed maternal parenting behavior (positive parenting, negative parenting and total maternal commands). A significant nonadditive association was found between maternal DAT1 genotype and both negative parenting and total commands during a structured mother–child interaction task, even after controlling demographic factors, maternal psychopathology and disruptive child behavior during the task. Furthermore, the association between maternal DAT1 genotype and negative parenting was significantly stronger among mothers whose children were highly disruptive during the mother–child interaction task, suggesting a gene–environment interaction.