Increased density of GAD65/67 immunoreactive neurons in the posterior subiculum and parahippocampal gyrus in treated patients with chronic schizophrenia.

OBJECTIVES: Alterations of glutamic acid decarboxylase (GAD) play a crucial role in schizophrenic pathology. While GAD has been studied in several brain regions, its expression in the posterior hippocampus formation has not been investigated in schizophrenia. METHODS: We studied the brains of 17 patients with chronic schizophrenia and 15 controls. Using the optical dissector method we counted GAD65/67 immunoreactive neurons and pyramidal cells in the posterior hippocampus, subiculum, and parahippocampal gyrus, and measured the cortical thickness in posterior subiculum and parahippocampal gyrus. Patients had received typical neuroleptics for the mean of 20.8 years. RESULTS: In the patients we observed a significant increase of GAD immunoreactive neurons in the subiculum (left/right P = 0.004) and the parahippocampal gyrus (left P = 0.001, right P = 0.006). The hippocampus showed no or only subtle trends towards higher GAD densities. The density of pyramidal neurons and cortical thickness did not differ between the groups. A significant association between GAD density and the duration of illness was found in women with schizophrenia. CONCLUSIONS: The current data on GAD65/67 indicates a dysregulation of the GABAergic system in schizophrenia patients that may be associated with cognitive decline. However, a long term effect of neuroleptics on the GABAergic system cannot be excluded.

A morphometric analysis of the septal nuclei in schizophrenia and affective disorders: reduced neuronal density in the lateral septal nucleus in bipolar disorder.

The septal nuclei are assumed to play a significant role in the pathophysiology of schizophrenia and affective disorders. The aim of this study was to morphometrically characterize the septal nuclei in patients with schizophrenia, bipolar disorder, and major depressive disorder, when compared with healthy control subjects. We analyzed the septal nuclei by determining the density and size of the neurons in postmortem brains in 17 patients with schizophrenia, 8 patients with bipolar disorder, 7 patients with major depressive disorder, and 14 control subjects matched for age and gender. There was a significant reduction in the neuronal density, but not in the mean cross-sectional area, in the lateral septal nucleus (P = 0.013) in patients with bipolar disorder when compared with control subjects. There were no significant changes in the neuronal density of the septal nuclei of the medial and lateral cell groups in patients with schizophrenia and major depressive disorder when compared with control subjects. There was a significant negative correlation between neuronal density in the lateral septal nucleus and disease duration in patients with major depressive disorder (P = 0.037, r = -0.9). The histopathological abnormality of the decreased neuronal density in the lateral septal nucleus, which is an important limbic region involved in emotions, might be a neuropathological correlate of bipolar disorder.

Reduced neuronal expression of insulin-degrading enzyme in the dorsolateral prefrontal cortex of patients with haloperidol-treated, chronic schizophrenia.

Insulin-degrading enzyme (IDE) is a neutral thiol metalloprotease, which cleaves insulin with high specificity. Additionally, IDE hydrolyzes Abeta, glucagon, IGF I and II, and beta-endorphin. We studied the expression of IDE protein in postmortem brains of patients with schizophrenia and controls because: (1) the gene encoding IDE is located on chromosome 10q23-q25, a gene locus linked to schizophrenia; (2) insulin resistance with brain insulin receptor deficits/receptor dysfunction was reported in schizophrenia; (3) the enzyme cleaves IGF-I and IGF-II which are implicated in the pathophysiology of the disease; and (4) brain gamma-endorphin levels, liberated from beta-endorphin exclusively by IDE, have been reported to be altered in schizophrenia. We counted the number of IDE immunoreactive neurons in the dorsolateral prefrontal cortex, the hypothalamic paraventricular and supraoptic nuclei, and the basal nucleus of Meynert of 14 patients with schizophrenia and 14 matched control cases. Patients had long-term haloperidol treatment. In addition, relative concentrations of IDE protein in the dorsolateral prefrontal cortex were estimated by Western blot analysis. There was a significantly reduced number of IDE expressing neurons and IDE protein content in the left and right dorsolateral prefrontal cortex in schizophrenia compared with controls, but not in other brain areas investigated. Results of our studies on the influence of haloperidol on IDE mRNA expression in SHSY5Y neuroblastoma cells, as well as the effect of long-term treatment with haloperidol on the number of IDE immunoreactive neurons in rat brain, indicate that haloperidol per se, is not responsible for the decreased neuronal expression of the enzyme in schizophrenics. Haloperidol however, might exert some effect on IDE, through changes of the expression levels of its substrates IGF-I and II, insulin and beta-endorphin. Reduced cortical IDE expression might be part of the disturbed insulin signaling cascades found in schizophrenia. Furthermore, it might contribute to the altered metabolism of certain neuropeptides (IGF-I and IGF-II, beta-endorphin), in schizophrenia.

Dopamine-glutamate abnormalities in the frontal cortex associated with the catechol-O-methyltransferase (COMT) in schizophrenia.

Catechol-O-methyltransferase (COMT) plays an important role in brain catecholamine metabolism. Several studies point to the involvement of COMT in schizophrenia. We applied COMT immunohistochemistry to paraffin-embedded brain sections and assessed the cell density of COMT expressing glial cells and COMT expressing neurons in the gray matter of the frontal cortex of patients with schizophrenia compared with control subjects. We found a significantly increased cell density of COMT expressing glial cells (p=0.003), but an unchanged cell density of COMT expressing neurons (p=0.778) in the gray matter of the frontal cortex of patients with schizophrenia compared with control subjects. Our study demonstrates that schizophrenia might involve increased COMT expression in glial cells in the frontal cortex, which might be associated with a neuronal-glial abnormality and a disturbed dopamine-glutamate interaction.

The volumes of the fornix in schizophrenia and affective disorders: a post-mortem study.

Structural and functional pathology of limbic structures including the hippocampus are frequently replicated in schizophrenia. Although the fornix is the main afferent system of the hippocampus to the septal nuclei and the hypothalamus (especially the mammillary bodies), relatively few studies have investigated structural changes of the fornix in schizophrenia. We measured the volume of the fornix in post-mortem brains in 19 patients with schizophrenia, 9 patients with bipolar disorder, 7 patients with unipolar depression, and 14 control subjects by planimetry of serial sections. The volumes, the mean cross-sectional areas, and the anterior to posterior distances of the fornix did not differ among patients with schizophrenia, bipolar disorder, unipolar depression, and control subjects. No lateralization existed between the right and the left fornices in among patients in the diagnostic groups and the control subjects. The fornix does not show morphometrical abnormalities in patients with schizophrenia, bipolar disorder and unipolar depression compared with control subjects, which might indicate that the fornix is not a primary focus of structural changes in these diseases.

Beacon-like/ubiquitin-5-like immunoreactivity is highly expressed in human hypothalamus and increased in haloperidol-treated schizophrenics and a rat model of schizophrenia.

The beacon gene is involved in the regulation of energy metabolism, food intake, and obesity. We localized its gene product, beacon-/ubiquitin 5-like immunoreactivity in brains of normal-weight, non-psychotic individuals, adipose (BMI over 32), non-psychotic individuals, and haloperidol-treated schizophrenics. The protein was found to be highly expressed in many neurons of the paraventricular and supraoptic hypothalamic nuclei. Besides, it was detected in neurons of other hypothalamic areas (suprachiasmatic, arcuate, and ventromedial nuclei) as well as outside the hypothalamus (Nuc. basalis Meynert, thalamus, hippocampus, and some neocortical areas). A morphometric analysis of beacon-immunoreactive hypothalamic and neocortical neurons revealed that compared to normal-weight controls in haloperidol-treated schizophrenics, there was a significant increase of protein-expressing supraoptic, paraventricular, and orbitofrontal neurons. However, a significant increase in beacon-expressing supraoptic neurons was also seen in adipose, non-psychotic individuals in comparison with normal-weight controls. Haloperidol at different doses has no effect on beacon expression in SHSY5Y neuroblastoma cells, which makes the assumption unlikely that haloperidol per se is responsible for the increased neuronal expression of the peptide in schizophrenics. In rats with a neonatal lesion of the ventral hippocampus (a widely used animal model of schizophrenia), we found an increased neuronal expression of beacon in the paraventricular and supraoptic nuclei. We suppose that elevated hypothalamic expression of beacon-like protein in non-obese schizophrenics is not primarily related to metabolic alterations, but to a certain role in schizophrenia, which is possibly unrelated to aspects of weight gain and obesity. The latter assumption finds some support by data obtained in rats with ventral hippocampus lesion.

Regional and cellular distribution patterns of insulin-degrading enzyme in the adult human brain and pituitary.

The regional distribution and cellular localization of insulin-degrading enzyme (IDE) was studied in adult human brain and pituitary by means of immunhistochemistry. We show that the enzyme is widely but unevenly distributed in human brain, with hypothalamic neurons showing the strongest immunoreaction. Strong to moderate immunostaining for the enzyme was observed in multiple cortical areas, hippocampus, cerebellum, and brain stem. Cellularly, IDE was mainly confined to neurons, but it was also present in oligodendrocytes, choroid plexus, and some blood vessel endothelial cells. A strong immunoreaction was seen in a subset of adenohypophysial cells. Some immunolabeling was also present in the neurohypophysis. The putative importance of the distribution of the enzyme in brain and pituitary is discussed in relation to its main known substrates, insulin, Abeta, and beta-endorphin.

Strongly reduced number of parvalbumin-immunoreactive projection neurons in the mammillary bodies in schizophrenia: further evidence for limbic neuropathology.

The mammillary bodies (MB) are important relay nuclei within limbic and extralimbic connections. They are known to play important roles in memory formation and are affected in alcoholism and vitamin B1 deficiency. Their strategic position linking temporo-limbic to cortico-thalamic brain structures make the MB a candidate brain structure for alterations in schizophrenia. We studied 15 postmortem brains of schizophrenics and 15 matched control brains. Brain sections were stained either with Heidenhain-Woelcke, glutamic acid decarboxylase (GAD), calretinin, or parvalbumin. We determined the volumes of the MB and performed cell countings using stereological principles and a computerized image analysis system. The volumes of MB do not differ between schizophrenics and controls. However, in schizophrenia the number of neurons as well as the resulting neuronal densities was significantly reduced on both sides (on left side by 38.9%, on right side by 22%). No changes were seen in the number of GAD-expressing or calretinin-containing neurons, whereas the number of parvalbumin-immunoreactive MB neurons was reduced by more than 50% in schizophrenia. This cell loss (as a result of developmental malformation and/or neurodegeneration) points to a prominent involvement of the MB in the pathomorphology of schizophrenia. Parvalbumin-immunoreactive GABAergic interneurons have been reported to be diminished in schizophrenia. However, in the MB parvalbumin labels a subpopulation of glutamate/aspartate-containing neurons projecting mainly to the anterior thalamus. Thus, our data provide new evidence for impaired limbic circuits in schizophrenia.

Volumetric analysis of septal region in schizophrenia and affective disorder.

MRI and post-mortem studies indicate an increased prevalence of cavum septi pellucidi (CSP) in schizophrenia and affective disorder. The aim of this study was to characterize the CSP and the septal tissue among patients with schizophrenia, patients with affective disorder, and control subjects. The volumes of CSP and septal tissue were measured in post-mortem brains in 42 patients with schizophrenia, 14 patients with affective disorder, and 17 normal control cases by planimetry of serial sections. Enlargements of CSP (>100 mm(3)) were found in eight of the 42 (19%) patients with schizophrenia. There were no significant differences in CSP volumes between patients with affective disorder and controls. Enlarged CSP in schizophrenia were not associated with reduced septal tissue volumes. By contrast, a significant positive correlation between volumes of CSP and septal tissue volumes in patients with schizophrenia (P = 0.03) and in control cases (P < 0.01) was found, but not in patients with affective disorder (P = 0.53). The finding of enlarged CSP in schizophrenia strongly supports the hypothesis of an early developmental abnormality in this key structure of the limbic system.

Localization of neuregulin-1alpha (heregulin-alpha) and one of its receptors, ErbB-4 tyrosine kinase, in developing and adult human brain.

Using immunohistochemistry, Western blot analysis, and RT-polymerase chain reaction, we studied the distribution of neuregulin-1 splice variant alpha (NRG-1alpha) and one of its putative receptors, ErbB-4 tyrosine kinase, in human brain. In the pre- and perinatal human brain immunoreactivity was confined to numerous neurons, with the highest cell density found in cortical gray matter, hypothalamus and cerebellum. In the adult brain, single cortical gray and white matter neurons showed NRG-1alpha immunoreactivity. Occasionally, immunoreactive oligodendrocytes were observed. NRG-1alpha-expressing neurons were also found in the hypothalamus, hippocampus, basal ganglia and brain stem. Application of two antibodies recognizing alpha and beta isoforms revealed a different distribution pattern in that many cortical and hippocampal pyramidal neurons were labeled. ErbB-4 immunoreactivity was expressed in both neurons and oligodendrocytes. Our data show that NRG-1alpha expression is lower in the adult human brain than in the developing brain, and, therefore, support a role for NRG-1alpha in brain development.

Volume and neuron number of the mediodorsal thalamic nucleus in schizophrenia: a replication study.

Previous neuropathological studies on the mediodorsal thalamic nucleus (MD) in schizophrenia have yielded conflicting results. While some studies suggested that patients with schizophrenia have a pronounced reduction of the volume and neuron number in the MD, more recent data have not found anatomical alterations in this thalamic nucleus. However, most studies have considerable methodological shortcomings. In the present study, we investigated the volume, neuron density and neuron number in the left and right MD in patients with schizophrenia (n=20) and normal control subjects without neuropsychiatric disorders (n=18). Patients with schizophrenia showed no significant difference in neuron density and total neuron number in the MD. Compared with the control group, patients with schizophrenia had a smaller MD volume in both hemispheres, a difference that approached significance in the left MD (-7.3%) when the whole brain volume was included as a covariate. No significant main group effect of diagnosis was found for the right MD volume. There were no significant correlations between MD volume, neuron density, total neuron number and the duration of illness or the age of the patients. Taken together, the present results suggest that schizophrenia is associated with a moderate volume reduction in the left mediodorsal thalamic nucleus, while the neuron density and the total neuron number are unchanged.

Volume deficits of subcortical nuclei in mood disorders A postmortem study.

Structural changes in subcortical nuclei may underlie clinical symptoms of mood disorders. The goal was to determine whether macrostructural changes exist in brain areas assumed to be involved in regulation of mood and whether such changes differ between major depressive disorder and bipolar disorder. A case-control design was used to compare volumes of all major subcortical nuclei. Brains of patients with major depressive disorder (n = 9) or bipolar disorder (n = 11) or of individuals without a neuropsychiatric disorder (n = 22) were included. Exclusion criteria were a history of substance abuse or histological signs of neurodegenerative disorders. Volumes of the striato-pallidal nuclei, of the hypothalamus, thalamus, amygdala, hippocampus and basal limbic forebrain were determined in the right and left hemisphere by planimetry of 20 mum whole brain serial paraffin sections. Comparisons between patients with bipolar disorder, major depressive disorder and controls showed a significant (Lambda = 0.35, F(20,56) = 1.93, P = 0.028) overall difference in volumes of all investigated regions with strong effect sizes ( f > 0.40) contributed by the hypothalamus, external pallidum, putamen and thalamus. As compared to controls, a strong effect size (f > 0.40) was found in the bipolar group for smaller volumes of the hypothalamus, external pallidum, putamen and thalamus,whereas in patients with major depressive disorder a strong effect size was only found for a smaller volume of the external pallidum. In conclusion our data suggest that pathways presumably involved in mood regulation have structural pathology in affective disorders with more pronounced abnormalities in bipolar disorder.

Volumes of association thalamic nuclei in schizophrenia: a postmortem study.

The major association thalamic nuclei, the mediodorsal nucleus (MD) and the medial pulvinar nucleus (PUM) are regarded as important parts of the circuits among association cortical regions. Association cortical regions of the frontal, parietal and temporal lobes have been repeatedly implicated in the neuropathology of schizophrenia. Thus, the aim of the present postmortem study was to investigate the volumes of association thalamic nuclei in this disease. The volumes of the whole thalamus (THAL), MD and PUM were measured in each hemisphere of brains of 12 patients with schizophrenia and 13 age-matched and gender-matched normal control subjects without neuropsychiatric disorders. Patients with schizophrenia exhibited significant volume reductions in both the MD and the PUM, the reductions being more pronounced in the PUM. The volume of the PUM in the left (-19.7%, P=0.02) and right (-22.1%, P=0.01) hemispheres was significantly reduced in the schizophrenia group. The volume of the MD was reduced in both hemispheres in the schizophrenia group. However, the volume reduction was only significant in the left hemisphere (-9.3%, P=0.03). Patients with schizophrenia also exhibited a decreased volume of the THAL in the left (-16.4%, P=0.003) and right (-15.2%, P=0.006) hemispheres. There were no significant correlations between thalamic volumes and duration of illness or age of the patients. In conclusion, the present data indicate volume reductions of association thalamic nuclei in schizophrenia. These anatomical findings are consistent with the view that schizophrenia may be associated with disturbances of association cortical networks. However, the findings of a substantial volume reduction of the THAL suggest that the volumes of additional thalamic nuclei may be also reduced in schizophrenia.

The ventral lateral posterior nucleus of the thalamus in schizophrenia: a post-mortem study.

The ventral lateral posterior thalamic nucleus (VLp) is an integral part of both the cerebello-thalamocortical and the basal ganglia-thalamocortical circuit. Although both circuits are thought to be involved in the pathophysiology of schizophrenia, the VLp has not yet been examined in schizophrenia. Using stereological techniques in the brains of eight patients with schizophrenia and in eight age- and sex-matched controls, we measured the nuclear volume of the VLp and obtained estimates of the total number of neurons in this nucleus. Whole brain volume did not differ between the schizophrenia group and the control group and was not correlated to the volume of the right VLp or left VLp. The volume (minus sign25%) and the total neuron number (minus sign27%) of the left VLp were significantly reduced in the schizophrenia group. There were no significant differences in the nuclear volume, neuron density and total neuron number in the right VLp between the schizophrenia group and the control group. There were no significant correlations between length of illness and the nuclear volume, neuron density and total neuron number of the left and right VLp. The present results suggest that the total neuron number of the left VLp is reduced in the schizophrenia group, which may reflect disturbed cerebello-thalamocortical and basal ganglia-thalamocortical circuits in this disease.