1. We examined dysbindin-1 mRNA in the hippocampal formation of and found reduced expression in dendate granule and polymorph cell and in hippocampus. There were positive correlations between dysbindin-1 mRNA and expression of synaptic markers known to be reduced in schizophrenics (SCZ). Our results indicate that previously reported dysbindin-1 protein reductions may be due in part to decreased dysbindin-1 mRNA and that reduced dysbindin-1 may contribute to hippocampal formation synaptic pathology in SCZ.? ? NRG1 and its receptor ErbB4, have been implicated in SCZ at both gene and transcript levels. Prefrontal cortex cytoplasmic NRG1 protein levels were significantly increased (20%) in SCZ relative to each of the other subject groups. We also detected diagnostic effects on prefrontal cortex cytoplasmic full-length ErbB4 protein levels and revealed that these quantities were significantly increased (30%) in SCZ relative to normals and depressed subjects. ? ? 2. Studies of the effects of allelic variations have shown that NRG1 regulates alpha-7 nicotinic acetylcholine receptor expression. We suspect that NRG1 SCZ-associated variations are related with changes in alpha-7 receptor levels. Consistent with mRNA findings, we found a decrease in receptor binding in subjects having both risk alleles as compared with those having only 1 risk allele.? ? We examined the effects of high-risk mutations in CNP and OLIG2 on mRNA levels in these genes and found the high-risk mutations in CNP and OLIG2, previously associated with SCZ, predicted low expression of these genes. We also found that MOBP mRNA levels were increased in the DLPFC white matter in SCZ with a history of substance abuse, MOBP and CNP protein in white matter was not altered. ? ? We studied genetic variation in GRM3 which has been associated with SCZ, but the mechanism by which it confers risk is unknown. This present study determined whether the expression of this splice variant is altered in SCZ and whether it is affected by a risk allele. Expression data of GRM3 mRNA in the DLPFC were inconsistent. GRM3 was increased in the CBDB/NIMH collection but not in the Stanley Array Collection. An exon 3 SNP associated with SCZ predicted increased expression on the GRM3 splice variant. Our results suggest that a mutation or neighboring linked mutation may contribute to risk for SCZ by modulating GRM3 splicing.? ? Hormones such as estrogen, modifies human emotion and cognition and impacts symptoms for SCZ. We hypothesized that the variation in ESR1 gene and cortical ESR1 mRNA are associated with SCZ. Schizophrenics with the """"""""at risk"""""""" PvuII genotype had lower ESR1 mRNA levels in the PFC. We detected 18 ESR1 splice variants and decreased wild-type ESR1 mRNA in SCZ. Thus, the variation in the ESR1 gene is associated with SCZ and the mechanism of this association may involve alternative gene regulation and mRNA transcript processing. In another study of estrogen, we compared the distribution of estrogen receptor (ER) alpha in human DLPFC with that of monkey DLPFC and rat medial PFC. We showed ER alpha positive cells throughout all layers of the PFC, in pyramidal and non-pyramidal neurons, in both the nucleus and cytoplasm. The present study provides evidence that ER alpha protein exists in neurons in mammalian PFC and that ER alpha is anatomically well-positioned to directly mediate estrogen action in these neurons.? ? HER4/ErbB4 is a receptor tyrosine kinase whose transcript undergoes alternative splicing in the brain. Disease-related variants in the ErbB4 gene implicate altered splicing of the gene. We examined ErbB4 splice-variant gene expression in the hippocampus and DLPFC in SCZ and investigated whether expression levels are associated with previously reported genomic risk variants in ErbB4 in a large cohort of human brains. In the DLPFC, we confirmed previous observations that mRNA for ErbB4 splice isoforms containing exon 16 (JM-a) and exon 26 (CYT-1) are significantly elevated in patients with SCZ. We provide a direct link between disease-related genetic variation and ErbB4 splice-variant mRNA expression levels in the human brain. ? ? 3. Our studies of SCZ susceptibility genes used custom DNA microarrays to examine the expression of 31 genes in the prefrontal cortex (PFC) of 72 postmortem normal brains from ages 18-67. NRG1, ERBB3 and NGFR show expression changes during the at risk years for the development of SCZ. Expression of FEZ1, GAD1, and RGS4 showed especially high correlation with one another, in addition to the strongest mean levels of absolute correlation with all other genes studied here.? ? 4. Substance use changes brain function both acutely and chronically. Human postmortem brain provides the only direct means to examine the cellular neurobiology associated with human substance use disorders, but such studies have a particular set of diagnostic challenges. Several diagnostic tools have been validated to assess substance use, abuse and dependence in living subjects but none address retrospective assessments of ante-mortem substance use in postmortem cases. It is current practice to establish a case history using all available sources of information. Our study examined the diagnostic challenges of identifying ante-mortem illicit substance use in human postmortem cases. Substance use, assessed by clinical case history reviews, next-of-kin interviews, toxicology of blood, urine/brain test, and scalp hair testing, identified 33 cocaine, 29 cannabis, 10 phencyclidine, and 9 opioid cases. Identifying ante-mortem substance use in human postmortem cases are key considerations in case diagnosis and for characterization of disorder-specific changes in neurobiology. The sensitivity and specificity of substance use assessments increased when medical examiner case history was supplemented with structured next-of-kin interviews to establish a detailed lifetime substance use history, while comprehensive toxicology and hair testing in particular increased detection of recent illicit substance use. ? ? 5. It has been proposed that a neonatal ventral hippocampal lesion (NVHL) induces behavioral and physiological anomalies mimicking pathophysiological changes of SCZ. We explored whether these changes are due to an altered dopamine modulation of pyramidal neurons. Whole cell recordings were used to examine the effects of dopamine and glutamate agonists on cell excitability. We found NMDA, AMPA, and D1 agonist increased excitability of deep layer pyramidal neurons. Cell excitability was significantly higher in brain slices from NVHL animals treated with NMDA and a D1 agonist. There were differences observed in slices from pre-pubertal rats which suggest the PFC DA and glutamine system become altered after puberty in NVHL rats. A disruption of PFC dopamine-glutamine interactions could contribute to the manifestation of SCZ-like symptoms in NVHL rats, a model proposed to mimic some of the cortical deficits observed in schizophrenia.
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