Gene expression of neuregulin-1 isoforms in different brain regions of elderly schizophrenia patients

One important risk gene in schizophrenia is neuregulin-1 (NRG1), which is expressed in different isoforms in the brain. To determine if alterations of NRG1 are present in schizophrenia, we measured gene expression of NRG1 and its main isoforms as well as the impact of genetic variation of NRG1 in an exploratory study examining three brain regions instead of only one as published so far. In all, we examined post-mortem samples from 11 schizophrenia patients and eight normal subjects. We investigated gene expression of total NRG1 and isoforms I, II and III by real-time PCR in the prefrontal cortex (Brodmann areas 9 and 10) and right hippocampal tissue. For the genetic study, we genotyped the NRG1 polymorphism SNP8NRG221533, which is within the core haplotype of the original publication. Compared to controls, gene expression of the NRG1 isoform I was decreased and isoform II increased in the prefrontal cortex (BA10) of schizophrenia patients. There were no statistically significant differences between individuals carrying at least one C allele of SNP8NRG221533 compared to individuals homozygous for the T allele. The decreased expression of NRG1 isoform I and overexpression of isoform II may be related to deficits in receptor function as well as abnormal migration and myelination. However, our study sample was small and results of this exploratory study should be verified in a larger sample.