Post-mortem Brain Tissue Of Patients Research Articles

Polyunsaturated Fatty Acids and their Related Enzymes in Postmortem Brain Tissues of Patients with Psychiatric Disorders

The first study on fatty acid composition of the postmortem brains of patients with psychiatric disorders was performed by Horrobin et al. in 1991, who found abnormalities in polyunsaturated fatty acids (PUFAs) in patients with schizophrenia. About a decade later, research in this field was re-started by Yao et al., followed by a number of other research groups. The results seem to show that the PUFA changes in psychiatric disorders may be specific to certain brain regions, but the underlying mechanisms remain unclear. Here we review these case-control studies of postmortem brain composition. Keywords: polyunsaturated fatty acids, case-control study, schizophrenia, bipolar disorder, major depressive disorder, postmortem brain

Polyunsaturated Fatty Acids and their Related Enzymes in Postmortem Brain Tissues of Patients with Psychiatric Disorders

Polyunsaturated Fatty Acids and their Related Enzymes in Postmortem Brain Tissues of Patients with Psychiatric Disorders

Epigenetics Links Nature and Nurture

Epigenetics Links Nature and Nurture

Increased xanthine oxidase in the thalamus and putamen in depression

A growing body of literature suggests persistent and selective structural changes in the cortico-limbic-thalamic-striatal system in patients with recurrent depressive disorder (DD). Oxidative stress is thought to play a key role in these processes. So far, the main scientific focus has been on antioxidant enzymes in this context. For the first time, this proof of concept study examines the activity of the free radicals producing the enzyme, xanthine oxidase (XO), directly in the cortico-limbic-thalamic-striatal system of patients with recurrent depression. The activity of XO was ascertained in the cortico-limbic-thalamic-striatal regions in post-mortem brain tissue of patients with recurrent depressive episodes and individuals without any neurological or psychiatric history (7/7). We measured the XO activity in following brain areas: hippocampus, regio entorhinalis, thalamus, putamen and caudate nucleus. In this study, we report a significant increase of XO activity in the thalamus and the putamen of patients with depression. Our findings contribute to the growing body of evidence suggesting that oxidative stress plays a pivotal role in certain brain areas in recurrent depressive disorder.

Inflammasome signaling at the heart of central nervous system pathology

Neuroinflammation is a complex innate response of neural tissue against harmful effects of diverse stimuli viz., pathogens, damaged cells and irritants within the Central Nervous System (CNS). Studies show that multiple inflammatory mediators including cytokines, chemokines and prostaglandins are elevated in the Cerebrospinal Fluid (CSF) and in post-mortem brain tissues of patients with history of neuroinflammatory conditions as well as neurodegenerative disorders like Alzheimer's disease, Parkinson's disease and Multiple Sclerosis. The innate immunity mediators in the brain, namely microglia and astrocytes, express certain Pattern Recognition Receptors (PRRs), which are always on 'high-alert' for pathogens or other inflammatory triggers and participate in the assembly and activation of the inflammasome. The inflammasome orchestrates the activation of the precursors of proinflammatory caspases, which in turn, cleave the precursor forms of interleukin-1beta, IL-18 and IL-33 into their active forms; the secretion of which leads to a potent inflammatory response, and/or influences the release of toxins from glial and endothelial cells. Altered expression of inflammasome mediators can either promote or inhibit neurodegenerative processes. Therefore, modulating the inflammasome machinery seems a better combat strategy than summarily suppressing all inflammation in most neuroinflammatory conditions. In the current review we have surveyed the identified triggers and pathways of inflammasome activation and the following events which ultimately accomplish the innate inflammatory response in the CNS, with a goal to provide an analytical insight into disease pathogenesis that might provide cues for devising novel therapeutic strategies.

Cyanobacterial neurotoxin BMAA in ALS and Alzheimer’s disease

The aim of this study was to screen for and quantify the neurotoxic amino acid beta-N-methylamino-L-alanine (BMAA) in a cohort of autopsy specimens taken from Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and non-neurological controls. BMAA is produced by cyanobacteria found in a variety of freshwater, marine, and terrestrial habitats. The possibility of geographically broad human exposure to BMAA had been suggested by the discovery of BMAA in brain tissues of Chamorro patients with ALS/Parkinsonism dementia complex from Guam and more recently in AD patients from North America. These observations warranted an independent study of possible BMAA exposures outside of the Guam ecosystem. Postmortem brain specimens were taken from neuropathologically confirmed cases of 13 ALS, 12 AD, 8 HD patients, and 12 age-matched non-neurological controls. BMAA was quantified using a validated fluorescent HPLC method previously used to detect BMAA in patients from Guam. Tandem mass spectrometric (MS) analysis was carried out to confirm the identification of BMAA in neurological specimens. We detected and quantified BMAA in neuroproteins from postmortem brain tissue of patients from the United States who died with sporadic AD and ALS but not HD. Incidental detections observed in two out of the 24 regions were analyzed from the controls. The concentrations of BMAA were below what had been reported previously in Chamarro ALS/ Parkinsonism dementia complex patients, but demonstrated a twofold range across disease and regional brain area comparisons. The presence of BMAA in these patients was confirmed by triple quadrupole liquid chromatography/mass spectrometry/mass spectrometry. The occurrence of BMAA in North American ALS and AD patients suggests the possibility of a gene/environment interaction, with BMAA triggering neurodegeneration in vulnerable individuals.

S29-03 How hormones influence gene expression: Implications to the pathophysiology of schizophrenia

Schizophrenia is a complex genetic disorder. The lack of concordance on disease manifestation in monozygotic twins provides clear evidence that environmental factors are key determinants in disease aetiology. In accordance, various environmental modulators such as hormones and vitamins may well contribute to the altered expression pattern of several genes identified in post-mortem brain tissue of patients. We constructed a microarray platform containing 1,808 human genes, where 142 belong to vitamin A, thyroid hormone and estrogens’ metabolic pathways, to specifically address whether these could contribute to a molecular signature of schizophrenia in peripheral lymphocytes. We found that the genes encoding for PLP1, UGT1A6, NTRK1, THRAP1, ESR2, TRIP13, MAPK8, TGFB2, IGFBP4 are differentially expressed in lymphocytes of patients under treatment with clozapine, risperdal or haloperidol. Some of these genes have been previously reported by others to be altered in brain regions of schizophrenic patients, and all are implicated in pathways suggested to be involved in the disease. These observations further support that:1.studies in peripheral blood lymphocytes may contribute to reveal candidate genes in schizophrenia;2.transcription modulation of several genes may occur through the mediation of vitamin and hormones, therefore linking genes and environment in schizophrenia.In order to understand the involvement of these genes in schizophrenia, future studies should investigate whether some of the observed changes are replicated in animal models of the disease, and how antipsychotic treatment interferes with their expression.

Profiles of matrix metalloproteinases and their inhibitors in plasma of patients with dementia

Matrix metalloproteinases (MMPs) are elevated in the brain tissue of patients with dementia and may play a role in the pathophysiology of dementia. MMP-9 and tissue inhibitors of MMPs (TIMPs) are elevated in postmortem brain tissue of patients with Alzheimer's disease (AD). In a previous study we showed that circulating levels of MMP-9 are elevated in AD patients. The aim of the present study was to examine circulating levels of MMP-1, MMP-2, MMP-9, TIMP-1 and TIMP-2 in the plasma of patients with mild cognitive impairment (MCI), AD, vascular dementia (VaD), dementia with Lewy bodies (DLB) and frontotemporal dementia (FTD), to determine, whether plasma profiles of MMPs and TIMPs differ in various types of dementia. Gelatinolytic activity (MMP-2 and MMP-9) was measured in all plasma samples by zymography. Levels of MMP-2, MMP-9, MMP-1 as well as TIMP-1 and TIMP-2 were measured by ELISA. We found constitutive expression of MMP-1, -2 and -9 as well as TIMP-1 and -2 in all the samples investigated. As shown previously, MMP-9 was significantly elevated in the plasma of AD patients (p = 0.004) as compared to controls and MCI patients. Plasma levels of TIMP-1 were significantly lower in VD samples as compared to all other groups. Levels of TIMP-2 were significantly lower in patients with FTD as compared to AD, VaD and MCI patients. There were no significant changes of MMP-1 and MMP-2 levels in the samples. These findings suggest that circulating levels of MMP-9, TIMP-1 and TIMP-2 and changes in the MMP/TIMP balance in plasma differ in various types of dementia.

Binding of two potential imaging agents targeting amyloid plaques in postmortem brain tissues of patients with Alzheimer's disease

In vivo imaging of amyloid plaques may be useful for evaluation and diagnosis of Alzheimer's disease (AD) patients. Towards that end, we have developed 6-iodo-2-(4′-dimethylamino-)phenyl-imidazo[1,2]pyridine (IMPY), and 4- N-methylamino-4′-hydroxystilbene (SB-13) as ligands for specifically targeting amyloid plaques. These ligands can be readily radiolabeled with I-123 or C-11, for in vivo imaging using single photon emission computerized tomography (SPECT) or positron emission tomography (PET), respectively. However, in order to be useful in vivo, probes must show selective high affinity binding to a sufficiently abundant binding site on amyloid plaques. Therefore, as a prelude to in vivo imaging studies, we evaluated the binding properties of these two potential imaging agents to amyloid plaques present in human brain tissues. In vitro binding studies were carried out with [ 125I]IMPY and [ 3H]SB-13 in homogenates prepared from postmortem samples of affected cortex and cerebellum of pathologically confirmed AD patients and age-matched controls. Binding parameters such as K d and B max were estimated. Competition study was designed to evaluate the amyloid plaque binding specificity using human brain tissues. Plaque binding was confirmed by thioflavin-S staining. Specific [ 125I]IMPY or [ 3H]SB-13 binding can be clearly measured in the cortical gray matter, but not in the white matter of AD cases. There was a very low specific binding in cortical tissue homogenates of control brains. Cerebellar homogenates prepared from either AD or control brains did not show any specific [ 125I]IMPY or [ 3H]SB-13 binding. The K d values of AD cortical homogenates were 5.3±1.0 and 2.4±0.2 nM for [ 125I]IMPY and [ 3H]SB-13, respectively. High binding capacity and comparable values were observed for both ligands (14–45 pmol/mg protein). The location and density of specific signal detected by [ 125I]IMPY or [ 3H]SB-13 correlated with the distribution of amyloid plaques in these brain specimens, as confirmed by thioflavin-S staining. Competition profiles of known ligands suggest that the binding is highly selective and comparable to that reported by using preformed Aβ peptide aggregates. [ 125I]IMPY and [ 3H]SB-13 show an abundant binding capacity with high binding affinities for amyloid plaques in affected cortical regions of AD brains. These properties suggest that when labeled with I-123 or C-11, these two ligands may be useful to quantitate amyloid plaque burdens in the living AD patients.

Behavioral and regulatory abnormalities in mice deficient in the NPAS1 and NPAS3 transcription factors.

Laboratory mice bearing inactivating mutations in the genes encoding the NPAS1 and NPAS3 transcription factors have been shown to exhibit a spectrum of behavioral and neurochemical abnormalities. Behavioral abnormalities included diminished startle response, as measured by prepulse inhibition, and impaired social recognition. NPAS1/NPAS3-deficient mice also exhibited stereotypic darting behavior at weaning and increased locomotor activity. Immunohistochemical staining assays showed that the NPAS1 and NPAS3 proteins are expressed in inhibitory interneurons and that the viability and anatomical distribution of these neurons are unaffected by the absence of either transcription factor. Adult brain tissues from NPAS3- and NPAS1/NPAS3-deficient mice exhibited a distinct reduction in reelin, a large, secreted protein whose expression has been reported to be attenuated in the postmortem brain tissue of patients with schizophrenia. These observations raise the possibility that a regulatory program controlled in inhibitory interneurons by the NPAS1 and NPAS3 transcription factors may be either substantively or tangentially relevant to psychosis.

Is Chlamydia pneumoniae present in brain lesions of patients with multiple sclerosis?

We investigated the presence of Chlamydia pneumoniae in 81 normal and pathological specimens obtained from postmortem brain tissues of patients with multiple sclerosis and with other neurological or nonneurological diseases. The assays used included PCR amplification of all DNA samples in the initial study. Culture and a second PCR amplification of the organism in a subset of 19 brain specimens were also performed in two separate laboratories. All results were negative. Thus, this study on a large number of brain tissues suggests that C. pneumoniae is not involved in inflammatory demyelination.

Serotonin Stimulation and Platelet Calcium Uptake in Depressed Patients

Platelets and post-mortem brain tissue of patients with major depression have shown increased numbers of 5HT2 receptors. In addition, previous studies have suggested that activation of the 5HT2 receptor results in calcium influx. This finding is …

Phenotypic down-regulation of glutamate receptor subunit GluR1 in Alzheimer’s disease☆

Glutamate receptors play crucial roles in cognition and memory. We have quantitated the protein levels of α-amino-isoxazolepropionic acid (AMPA)-type (GluR1) and N-methyl-d-aspartate-type (NMDAR1) glutamate receptors in postmortem brain tissues of patients with Alzheimer’s disease and age-matched controls using western blotting. The bolts carrying fully denatured proteins were probed with antibodies specific to their carboxyl terminus of these receptors. In Alzheimer’s disease, GluR1 levels were significantly decreased in the entorhinal cortex and dentate gyrus, but not in the motor cortex. In contrast, levels of NMDAR1 were not altered in the dentate gyrus, suggesting that GluR1 expression was specifically diminished in this structure that is known to be preserved histologically in patients. However, the results of immunocytochemical examination confirmed a previous controversial report: GluR1-immunoreactive structures were labeled rather intensely in the molecular layer of the dentate gyrus of Alzheimer’s patients. Interestingly, levels of a postsynaptic density protein named SAP97, which recognizes and potentially masks the epitope region of GluR1, was positively correlated with those of GluR1 protein in the control group, but not in the patient group. Thus, the enhanced GluR1-like staining in Alzheimer’s disease might be ascribed to the hampered interaction between SAP97 and GluR1 leading to epitope unmasking of GluR1 on tissue sections. These findings indicate that abnormal expressions of the AMPA receptor and its interacting PSD molecule are associated with Alzheimer’s disease and implicated in pathophysiology of this disease.

Nuclear factor-κB/Rel proteins: A point of convergence of signalling pathways relevant in neuronal function and dysfunction

Nuclear factor-κB (NF-κB)/Rel designates a family of transcription factors participating in the activation of a wide range of genes crucially involved in immune and inflammatory function. NF-κB/Rel proteins have been demonstrated recently in primary neurons and in several brain areas. Functional significance of these proteins is still not understood completely, but since certain subsets of neurons appear to contain constitutively active DNA-binding activity, it seems likely that they may participate in normal brain function. A growing body of evidence is accumulating for a specific activation of NF-κB/Rel proteins in the CNS, and in particular in neuronal cells, during neurodegenerative processes associated to etiologically unrelated conditions. Whether NF-κB activation is part of the neurodegenerative process or of protective mechanisms is a matter of debate. This issue will be reviewed here with particular attention to the available reports on the activity of NF-κB/Rel proteins in both experimental paradigms of neurodegeneration and post-mortem brain tissue of patients affected by various neurological diseases. We hypothesize that NF-κB/Rel proteins may represent the point of convergence of several signalling pathways relevant for initiating or accelerating the process of neuronal dysfunction and degeneration in many neurological diseases, including Parkinson’s disease, Alzheimer’s disease, CNS viral infections, and possibly others. If NF-κB/Rel proteins represent an integrating point of several pathways potentially contributing to neuronal degeneration, molecules that finely modulate their activity could represent a novel pharmacological approach to several neurological diseases.

Single-laser three-color immunolabeling of a histological section by laser scanning microscopy: application to senile plaque-related structures in post-mortem human brain tissue.

We describe a method for observing three-color immunofluorescence simultaneously in a histological section under a confocal laser scanning microscope. In this study we investigated the spatial relationship of blood vessels, reactive microglia, and amyloid beta-protein (A beta) deposits in post-mortem brain tissue of patients with Alzheimer's disease. HLA-DR was employed as a marker for activated microglia and von Willebrand factor (vWF) as a marker for vascular endothelial cells. HLA-DR was labeled with R-phycoerythrin (R-PE) and vWF with fluorescein isothiocyanate. A beta-protein was immunostained with the tandem conjugate of R-PE and cyanin 5. Three images were obtained serially by scanning a tissue section with a 488-nm laser beam in combination with an appropriate emission filter for each fluorochrome. Overlaying of these three images permitted simultaneous observation of three distinct structures: activated microglia, blood vessels, and A beta deposits. This technique provides an improved way to study the localization of three different antigens in a single tissue section.

Quinolinic acid and kynurenine pathway metabolism in inflammatory and non-inflammatory neurological disease.

Neurological dysfunction, seizures and brain atrophy occur in a broad spectrum of acute and chronic neurological diseases. In certain instances, over-stimulation of N-methyl-D-aspartate receptors has been implicated. Quinolinic acid (QUIN) is an endogenous N-methyl-D-aspartate receptor agonist synthesized from L-tryptophan via the kynurenine pathway and thereby has the potential of mediating N-methyl-D-aspartate neuronal damage and dysfunction. Conversely, the related metabolite, kynurenic acid, is an antagonist of N-methyl-D-aspartate receptors and could modulate the neurotoxic effects of QUIN as well as disrupt excitatory amino acid neurotransmission. In the present study, markedly increased concentrations of QUIN were found in both lumbar cerebrospinal fluid (CSF) and post-mortem brain tissue of patients with inflammatory diseases (bacterial, viral, fungal and parasitic infections, meningitis, autoimmune diseases and septicaemia) independent of breakdown of the blood-brain barrier. The concentrations of kynurenic acid were also increased, but generally to a lesser degree than the increases in QUIN. In contrast, no increases in CSF QUIN were found in chronic neurodegenerative disorders, depression or myoclonic seizure disorders, while CSF kynurenic acid concentrations were significantly lower in Huntington's disease and Alzheimer's disease. In inflammatory disease patients, proportional increases in CSF L-kynurenine and reduced L-tryptophan accompanied the increases in CSF QUIN and kynurenic acid. These responses are consistent with induction of indoleamine-2,3-dioxygenase, the first enzyme of the kynurenine pathway which converts L-tryptophan to kynurenic acid and QUIN. Indeed, increases in both indoleamine-2,3-dioxygenase activity and QUIN concentrations were observed in the cerebral cortex of macaques infected with retrovirus, particularly those with local inflammatory lesions. Correlations between CSF QUIN, kynurenic acid and L-kynurenine with markers of immune stimulation (neopterin, white blood cell counts and IgG levels) indicate a relationship between accelerated kynurenine pathway metabolism and the degree of intracerebral immune stimulation. We conclude that inflammatory diseases are associated with accumulation of QUIN, kynurenic acid and L-kynurenine within the central nervous system, but that the available data do not support a role for QUIN in the aetiology of Huntington's disease or Alzheimer's disease. In conjunction with our previous reports that CSF QUIN concentrations are correlated to objective measures of neuropsychological deficits in HIV-1-infected patients, we hypothesize that QUIN and kynurenic acid are mediators of neuronal dysfunction and nerve cell death in inflammatory diseases. Therefore, strategies to attenuate the neurological effects of kynurenine pathway metabolites or attenuate the rate of their synthesis offer new approaches to therapy.

CCK receptors and human neurological disease

Cholecystokinin (CCK) receptor binding was measured in postmortem brain tissue of patients with Alzheimer's dementia, Huntington's chorea, and neurologically healthy matched controls. CCK binding was significantly reduced in the basal ganglia and cerebral cortex of Huntington's patients, but was normal in the temporal and cingulate cortex of patients with Alzheimer's disease. These findings indicate that CCK receptor loss is unique to specific neurodegenerative disease(s), and that CCK may be involved in the symptoms of Huntington's disease but is not implicated in the neuropathology of Alzheimer's dementia.