1Pharmacogenet. Genomics 2011 Apr 21: 206-16
TitleGlutamatergic gene variants impact the clinical profile of efficacy and side effects of haloperidol.
AbstractThe glutamatergic system may be relevant to the pathophysiology of psychosis and to the effects of antipsychotic treatments.
We investigated a set of 62 SNPs located in genes coding for subunits of glutamatergic receptors (GAD1, GRIA1, GRIA3, GRIA4, GRID2, GRIK1, GRIK2, GRIK3, GRIK4, GRIN2B, GRM1 and GRM4), and the transporter of glycine (SLC6A5), as modulators of the effects of haloperidol.
We studied a sample of 101 acutely ill psychotic patients. We then validated our result in two independent samples from Slovenia (n=71 and n=118) of schizophrenic patients treated with antipsychotics. We both investigated the antipsychotic effect (Positive and Negative Syndrome Scale) and motor side effect (Extrapyramidal Symptom Rating Scale) at baseline and days 3, 7, 14, 21 and 28. SLC6A5 variant (rs2298826) was found to be associated with a rapid rise of motor side effects at the beginning of the treatment (repeated measures of analysis of variance, P=0.0002), followed by a subsequent adaptation, probably dependent on haloperidol doses down titration. A specific effect was noted for dyskinetic symptoms. Haplotype analysis strengthened the relevance of SLC6A5: the C-A-C haplotype (rs1443548, rs883377, rs1945771) was found to be associated with higher Extrapyramidal symptom rating scale scores (overall P=0.01, haplotype P=0.000001). We successfully replicated this finding in the two independent samples from Slovenia.
This result further stresses the relevance of the glutamatergic system in modulating the effects of haloperidol treatment, especially with regards to motor side effects.
SCZ Keywordsschizophrenia, schizophrenic
2Psychopharmacology (Berl.) 2012 Dec 224: 349-62
TitleFronto-temporal-mesolimbic gene expression and heritable differences in amphetamine-disrupted sensorimotor gating in rats.
AbstractDifferences in sensitivity to the prepulse inhibition (PPI)-disruptive effects of D2-family agonists in Sprague-Dawley (SD) vs. Long Evans (LE) rats are heritable, reflect differential activation of DA signaling in the nucleus accumbens (NAC), and are associated with differences in expression of specific NAC genes. These differences may inform us about the biology of PPI deficits in disorders such as schizophrenia.
After confirming these strain-based PPI differences, we measured expression of four genes in NAC and other regions that regulate PPI: medial prefrontal cortex and ventral hippocampus (VH).
Startle and PPI were assessed in SD and LE rats administered D-amphetamine (0 vs. 4.5 mg/kg, sc). Two weeks later, brain tissue was processed for comt, nrg1, GRID2, and csnk1e expression; blood comt expression was also tested.
Data confirmed expected PPI phenotypes. Gene expression levels differed across strains, sexes, and brain regions, with LE > SD expression in most genes and regions, and female > male expression for all NAC genes. Within any brain region, expression of the four genes was highly inter-correlated; across regions, correlations were less robust, reflecting distinct strain- or sex-based subgroups. PPI amphetamine sensitivity at 120 ms correlated significantly with NAC nrg1 expression, while amphetamine sensitivity for 30 ms PPI and startle magnitude correlated significantly with VH nrg1 and blood comt expression.
Rat strains differing in a schizophrenia-linked phenotype also differ in expression levels of genes associated both with that phenotype, and with schizophrenia, within brain regions associated with that phenotype and schizophrenia.
SCZ Keywordsschizophrenia, schizophrenic
3Behav. Brain Res. 2013 Nov 257: 118-28
TitleForebrain gene expression predicts deficits in sensorimotor gating after isolation rearing in male rats.
AbstractCompared to socially housed (SH) rats, adult isolation-reared (IR) rats exhibit phenotypes relevant to schizophrenia (SZ), including reduced prepulse inhibition (PPI) of startle. PPI is normally regulated by the medial prefrontal cortex (mPFC) and nucleus accumbens (NAC). We assessed PPI, auditory-evoked local field potentials (LFPs) and expression of seven PPI- and SZ-related genes in the mPFC and NAC, in IR and SH rats. Buffalo (BUF) rats were raised in same-sex groups of 2-3 (SH) or in isolation (IR). PPI was measured early (d53) and later in adulthood (d74); LFPs were measured approximately on d66. Brains were processed for RT-PCR measures of mPFC and NAC expression of Comt, Erbb4, GRID2, Ncam1, Slc1a2, Nrg1 and Reln. Male IR rats exhibited PPI deficits, most pronounced at d53; male and female IR rats had significantly elevated startle magnitude on both test days. Gene expression levels were not significantly altered by IR. PPI levels (d53) were positively correlated with mPFC expression of several genes, and negatively correlated with NAC expression of several genes, in male IR but not SH rats. Late (P90) LFP amplitudes correlated significantly with expression levels of 6/7 mPFC genes in male rats, independent of rearing. After IR that disrupts early adult PPI in male BUF rats, expression levels of PPI- and SZ-associated genes in the mPFC correlate positively with PPI, and levels in the NAC correlate negatively with PPI. These results support the model that specific gene-behavior relationships moderate the impact of early-life experience on SZ-linked behavioral and neurophysiological markers.
SCZ Keywordsschizophrenia, schizophrenic
4Neuropharmacology 2013 Dec 75: 38-46
TitleCoupling of gene expression in medial prefrontal cortex and nucleus accumbens after neonatal ventral hippocampal lesions accompanies deficits in sensorimotor gating and auditory processing in rats.
AbstractAfter neonatal ventral hippocampal lesions (NVHLs), adult rats exhibit evidence of neural processing deficits relevant to schizophrenia, including reduced prepulse inhibition (PPI) of acoustic startle and impaired sensory processing. In intact rats, the regulation of PPI by the ventral hippocampus (VH) is mediated via interactions with medial prefrontal cortex (mPFC) and nucleus accumbens (NAC). We assessed PPI, auditory-evoked responses and expression of 7 schizophrenia-related genes in mPFC and NAC, in adult rats after sham- or real NVHLs.
Male inbred Buffalo (BUF) rat pups (d7; n=36) received either vehicle or ibotenic acid infusion into the VH. PPI and auditory-evoked dentate gyrus local field potentials (LFPs) were measured on d56 and d66, respectively. Brains were processed for RT-PCR measures of mPFC and NAC Comt, Erbb4, GRID2, Ncam1, Slc1a2, Nrg1 and Reln.
NVHL rats exhibited significant deficits in PPI (p=0.005) and LFPs (p<0.015) proportional to lesion size. Sham vs. NVHL rats did not differ in gene expression levels in mPFC or NAC. As we previously reported, multiple gene expression levels were highly correlated within- (mean r's?0.5), but not across-brain regions (mean r's?0). However, for three genes--Comt, Slc1a2 and Ncam1--after NVHLs, expression levels became significantly correlated, or "coupled," across the mPFC and NAC (p's<0.03, 0.002 and 0.05, respectively), and the degree of "coupling" increased with VH lesion size.
After NVHLs that disrupt PPI and auditory processing, specific gene expression levels suggest an abnormal functional coupling of the mPFC and NAC. This model of VH-mPFC-NAC network dysfunction after NVHLs may have implications for understanding the neural basis for PPI- and related sensory processing deficits in schizophrenia patients.
SCZ Keywordsschizophrenia, schizophrenic
5Schizophr. Res. 2016 Jan 170: 30-40
TitleGenetic assessment of additional endophenotypes from the Consortium on the Genetics of Schizophrenia Family Study.
AbstractThe Consortium on the Genetics of schizophrenia Family Study (COGS-1) has previously reported our efforts to characterize the genetic architecture of 12 primary endophenotypes for schizophrenia. We now report the characterization of 13 additional measures derived from the same endophenotype test paradigms in the COGS-1 families. Nine of the measures were found to discriminate between schizophrenia patients and controls, were significantly heritable (31 to 62%), and were sufficiently independent of previously assessed endophenotypes, demonstrating utility as additional endophenotypes. Genotyping via a custom array of 1536 SNPs from 94 candidate genes identified associations for CTNNA2, ERBB4, GRID1, GRID2, GRIK3, GRIK4, GRIN2B, NOS1AP, NRG1, and RELN across multiple endophenotypes. An experiment-wide p value of 0.003 suggested that the associations across all SNPs and endophenotypes collectively exceeded chance. Linkage analyses performed using a genome-wide SNP array further identified significant or suggestive linkage for six of the candidate endophenotypes, with several genes of interest located beneath the linkage peaks (e.g., CSMD1, DISC1, DLGAP2, GRIK2, GRIN3A, and SLC6A3). While the partial convergence of the association and linkage likely reflects differences in density of gene coverage provided by the distinct genotyping platforms, it is also likely an indication of the differential contribution of rare and common variants for some genes and methodological differences in detection ability. Still, many of the genes implicated by COGS through endophenotypes have been identified by independent studies of common, rare, and de novo variation in schizophrenia, all converging on a functional genetic network related to glutamatergic neurotransmission that warrants further investigation.
SCZ Keywordsschizophrenia, schizophrenic
6Transl Psychiatry 2016 -1 6: e739
TitleAntipsychotic pharmacogenomics in first episode psychosis: a role for glutamate genes.
AbstractGenetic factors may underlie beneficial and adverse responses to antipsychotic treatment. These relationships may be easier to identify among patients early in the course of disease who have limited exposure to antipsychotic drugs. We examined 86 first episode patients (schizophrenia, psychotic bipolar disorder and major depressive disorder with psychotic features) who had minimal to no prior antipsychotic exposure in a 6-week pharmacogenomic study of antipsychotic treatment response. Response was measured by change in Brief Psychiatric Rating Scale total score. Risperidone monotherapy was the primary antipsychotic treatment. Pharmacogenomic association studies were completed to (1) examine candidate single-nucleotide polymorphisms (SNPs) in genes known to be involved with glutamate signaling, and (2) conduct an exploratory genome-wide association study of symptom response to identify potential novel associations for future investigation. Two SNPs in GRM7 (rs2069062 and rs2014195) were significantly associated with antipsychotic response in candidate gene analysis, as were two SNPs in the human glutamate receptor delta 2 (GRID2) gene (rs9307122 and rs1875705) in genome-wide association analysis. Further examination of these findings with those from a separate risperidone-treated study sample demonstrated that top SNPs in both studies were overrepresented in glutamate genes and that there were similarities in neurodevelopmental gene categories associated with drug response from both study samples. These associations indicate a role for gene variants related to glutamate signaling and antipsychotic response with more broad association patterns indicating the potential importance of genes involved in neuronal development.
SCZ Keywordsschizophrenia, schizophrenic