Different distribution patterns of lymphocytes and microglia in the hippocampus of patients with residual versus paranoid schizophrenia: further evidence for disease course-related immune alterations?

Certain cytokines have been identified in the peripheral blood as trait markers of schizophrenia, while others are considered relapse-related state markers. Furthermore, data from peripheral blood, cerebrospinal fluid (CSF) and nuclear imaging studies suggest that (1) blood-brain barrier (BBB) dysfunction (e.g., immigration of lymphocytes into brain tissue and intrathecal antibody production) correlates with the development of negative symptoms, while (2) the brain's mononuclear phagocyte system (microglial cells) is activated during acute psychosis. Based on these neuroinflammatory hypotheses, we have quantified the numerical density of immunostained CD3+ T-lymphocytes, CD20+ B-lymphocytes, and HLA-DR+ microglial cells in the posterior hippocampus of 17 schizophrenia patients and 11 matched controls. Disease course-related immune alterations were considered by a separate analysis of residual (prevailing negative symptoms, n=7) and paranoid (prominent positive symptoms, n=10) schizophrenia cases. Higher densities of CD3+ and CD20+ lymphocytes were observed in residual versus paranoid schizophrenia (CD 3: left: P=0.047, right: P=0.038; CD20: left: P=0.020, right: P=0.010) and controls (CD3: left: P=0.057, right: P=0.069; CD20: left: P=0.008, right: P=0.006). In contrast, HLA-DR+ microglia were increased in paranoid schizophrenia versus residual schizophrenia (left: P=0.030, right: P=0.012). A similar trend emerged when this group was compared to controls (left: P=0.090, right: P=0.090). BBB impairment and infiltration of T cells and B cells may contribute to the pathophysiology of residual schizophrenia, while microglial activation seems to play a role in paranoid schizophrenia. The identification of diverse immune endophenotypes may facilitate the development of distinct anti-inflammatory schizophrenia therapies to normalize BBB function, (auto)antibody production or microglial activity.

A postmortem assessment of mammillary body volume, neuronal number and densities, and fornix volume in subjects with mood disorders.

Mammillary bodies are relay nuclei within limbic and extralimbic connections. Whereas other subcortical brain structures have been found to be altered in depression, no current information exists regarding the pathomorphology of mammillary bodies in affective disorders. We studied the postmortem brains of 19 human subjects with mood disorders (9 with major depressive disorder and 10 with bipolar I disorder) and 20 control individuals and assessed the mammillary body and fornix volumes, number of neurons and neuronal densities. We found that male control subjects have significantly larger mammillary bodies compared with females. In addition, control subjects of both sexes with the diagnosis/cause of death of "heart failure/insufficiency" had significantly smaller mammillary body volumes compared with non-psychiatric patients who died from other causes. When estimating the mammillary bodies volumes of patients with depression compared with control subjects, a significant reduction of the left mammillary body volume was found in patients with bipolar disorder, but not in patients with major depression. However, significant depression-associated mammillary body volume reductions were found between the control subjects who did not die of heart failure and patients with major depression and bipolar disorder. Moreover, the MB volumes of control subjects who died of heart failure were in the range exhibited by subjects with depression. There was no significant influence of suicidal behavior on mammillary volumes observed. Moreover, no significant group differences in the total neuronal number or neuronal density were found between the controls, subjects with major depression and subjects with bipolar disorder. Furthermore, the fornix volumes were significantly reduced only in the control subjects with heart failure. Taken together, these results show that the mammillary bodies are compromised in depression.

Reduced density of hypothalamic VGF-immunoreactive neurons in schizophrenia: a potential link to impaired growth factor signaling and energy homeostasis.

Protein expression of VGF (nonacronymic) is induced by nerve/brain-derived growth factor, neurotrophin 3, and insulin. VGF is synthesized by neurons in the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus. After enzymatic processing, smaller VGF-derived peptides are secreted into the cerebrospinal fluid (CSF) or blood. These peptides play important roles by improving synaptic plasticity, neurogenesis, and energy homeostasis, which are impaired in schizophrenia. Based on previous observations of neuroendocrine and hypothalamic deficits in schizophrenia and to determine whether increased levels of the VGF fragment 23-62 in CSF, which have been described in a recent study, were related to changes in hypothalamic VGF expression, an immunohistochemical study was performed in 20 patients with schizophrenia and 19 matched control subjects. N- (D-20) and C-terminal (R-15) VGF antibodies yielded similar results and immunolabeled a vast majority of PVN and SON neurons. Additionally, D20-VGF immunohistochemistry revealed immunostained fibers in the pituitary stalk and neurohypophysis that ended at vessel walls, suggesting axonal transport and VGF secretion. The cell density of D20-VGF-immunoreactive neurons was reduced in the left PVN (P = 0.002) and SON (P = 0.008) of patients with schizophrenia. This study provides the first evidence for diminished hypothalamic VGF levels in schizophrenia, which might suggest increased protein secretion. Our finding was particularly significant in subjects without metabolic syndrome (patients with a body mass index ≤28.7 kg/m(2)). In conclusion, apart from beneficial effects on synaptic plasticity and neurogenesis, VGF may be linked to schizophrenia-related alterations in energy homeostasis.

Differences between unipolar and bipolar I depression in the quantitative analysis of glutamic acid decarboxylase-immunoreactive neuropil.

Alterations in GABAergic neurotransmission are assumed to play a crucial role in the pathophysiology of mood disorders. Glutamic acid decarboxylase (GAD) is the key enzyme in GABA synthesis. This study aimed to differentiate between unipolar and bipolar I depression using quantitative evaluation of GAD-immunoreactive (GAD-ir) neuropil in several brain regions known to be involved in the pathophysiology of mood disorders. Immunohistochemical staining of GAD 65/67 was performed in the orbitofrontal, anterior cingulate and dorsolateral prefrontal cortex (DLPFC), the entorhinal cortex, the hippocampal formation and the medial dorsal and lateral dorsal (LD) thalamic nuclei, with a quantitative densitometric analysis of GAD-ir neuropil. The study was performed on paraffin-embedded brains from 9 unipolar and 12 bipolar I depressed patients (8 and 6 suicidal patients, respectively) and 18 matched controls. In unipolar patients, compared with controls, only the increased relative density of GAD-ir neuropil in the right LD was different from the previous results in depressed suicides from the same cohort (Gos et al. in J Affect Disord 113:45-55, 2009). On the other hand, the left DLPFC was the only area where a significant decrease was observed, specific for bipolar I depression. Significant differences between both diagnostic groups were found in these regions. By revealing abnormalities in the relative density of GAD-ir neuropil in brain structures, our study suggests a diathesis of the GABAergic system in mood disorders, which may differentiate the pathophysiology of unipolar from that of bipolar I depression.

Severe depression is associated with increased microglial quinolinic acid in subregions of the anterior cingulate gyrus: evidence for an immune-modulated glutamatergic neurotransmission?

BACKGROUND: Immune dysfunction, including monocytosis and increased blood levels of interleukin-1, interleukin-6 and tumour necrosis factor α has been observed during acute episodes of major depression. These peripheral immune processes may be accompanied by microglial activation in subregions of the anterior cingulate cortex where depression-associated alterations of glutamatergic neurotransmission have been described. METHODS: Microglial immunoreactivity of the N-methyl-D-aspartate (NMDA) glutamate receptor agonist quinolinic acid (QUIN) in the subgenual anterior cingulate cortex (sACC), anterior midcingulate cortex (aMCC) and pregenual anterior cingulate cortex (pACC) of 12 acutely depressed suicidal patients (major depressive disorder/MDD, n = 7; bipolar disorder/BD, n = 5) was analyzed using immunohistochemistry and compared with its expression in 10 healthy control subjects. RESULTS: Depressed patients had a significantly increased density of QUIN-positive cells in the sACC (P = 0.003) and the aMCC (P = 0.015) compared to controls. In contrast, counts of QUIN-positive cells in the pACC did not differ between the groups (P = 0.558). Post-hoc tests showed that significant findings were attributed to MDD and were absent in BD. CONCLUSIONS: These results add a novel link to the immune hypothesis of depression by providing evidence for an upregulation of microglial QUIN in brain regions known to be responsive to infusion of NMDA antagonists such as ketamine. Further work in this area could lead to a greater understanding of the pathophysiology of depressive disorders and pave the way for novel NMDA receptor therapies or immune-modulating strategies.

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.

Suicide and depression in the quantitative analysis of glutamic acid decarboxylase-Immunoreactive neuropil.

BACKGROUND: Alterations of GABAergic neurotransmission are assumed to play a crucial role in the pathophysiology of mood disorders. Glutamic acid decarboxylase (GAD) is the key enzyme of GABA synthesis. METHODS: Immunohistochemical staining of GAD 65/67 was performed in the orbitofrontal, anterior cingulate and dorsolateral prefrontal cortex (DLC), the entorhinal cortex (EC), the hippocampal formation, and the medial dorsal and lateral dorsal thalamic nuclei, with consecutive determination of GAD-immunoreactive (-ir) neuropil relative density. The study was performed on paraffin-embedded brains from 21 depressed patients (14 of whom had committed suicide) and 18 matched controls. The data were tested using Kruskal-Wallis, Mann-Whitney (U) and Spearman statistical procedures. RESULTS: As shown by post-hoc U-tests, an increase in the relative density of GAD-ir neuropil was present in the hippocampal formation, specific for suicidal patients. The EC was the only area where non-suicidal patients also revealed an increase compared with controls. On the contrary, the DLC was the only area where a significant decrease existed, specific for non-suicidal patients. Numerous negative correlations were found between the investigated parameter and psychotropic medication. LIMITATIONS: A major limitation of this study is the relatively small case number. A further limitation is given by the lack of data on drug exposure across the whole life span. The possible impact of unipolar-bipolar dichotomy of mood disorders on the obtained results should also be considered. CONCLUSION: The study, revealing predominantly an increased relative density of GAD-ir neuropil, suggests the diathesis of GABAergic system specific for depressed suicidal patients.

Immunological aspects in the neurobiology of suicide: elevated microglial density in schizophrenia and depression is associated with suicide.

OBJECTIVES: Suicide has a high prevalence in patients with schizophrenia and affective disorder. Our recent postmortem study [Steiner J, Mawrin C, Ziegeler A, Bielau H, Ullrich O, Bernstein HG, Bogerts B. Distribution of HLA-DR-positive microglia in schizophrenia reflects impaired cerebral lateralization. Acta Neuropathologica (Berl) 2006;112:305-16.] revealed increased microglial densities in two schizophrenic patients who had committed suicide. Therefore, the hypothesis of microglial activation during acute psychosis was proposed. Alternatively, "suicide" could be a diagnosis-independent factor leading to microgliosis. METHODS: To clarify this question, microglial HLA-DR expression was analyzed by immunohistochemistry in the dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), mediodorsal thalamus (MD) and hippocampus of 16 schizophrenics, 14 depressed patients with affective disorder and 10 matched controls. A subgroup of six schizophrenics and seven patients with affective disorder who committed suicide was included. RESULTS: ANOVA revealed no effect of diagnosis on microglial density (DLPFC: P=0.469; ACC: P=0.349; MD: P=0.569; hippocampus: P=0.497). However, significant microgliosis was observed in the DLPFC (P=0.004), ACC (P=0.012) and MD (P=0.004) of suicide patients. A similar trend was seen in the hippocampus (P=0.057). CONCLUSION: In conclusion, immunological factors may play a hitherto underestimated role in suicide. First, microglial activation might be interpreted as a consequence of presuicidal stress. Second, one might speculate a causal link between microglial activation and suicidal behaviour, such as neuroendocrine factors, cytokines, and nitric oxide, which are released from microglial cells and are known to modulate noradrenergic or serotonergic neurotransmission and thus may trigger suicidality.

S100B-immunopositive glia is elevated in paranoid as compared to residual schizophrenia: a morphometric study.

OBJECTIVE: Several studies have revealed increased S100B levels in peripheral blood and cerebrospinal fluid (CSF) of patients with schizophrenia. In this context, it was postulated that elevated levels of S100B may indicate changes of pathophysiological significance to brain tissue in general and astrocytes in particular. However, no histological study has been published on the cellular distribution of S100B in the brain of individuals with schizophrenia to clarify this hypothesis. METHODS: The cell-density of S100B-immunopositive glia was analyzed in the anterior cingulate, dorsolateral prefrontal (DLPF), orbitofrontal, and superior temporal cortices/adjacent white matter, pyramidal layer/alveus of the hippocampus, and the mediodorsal thalamic nucleus of 18 patients with schizophrenia and 16 matched control subjects. RESULTS: Cortical brain regions contained more S100B-immunopositive glia in the schizophrenia group relative to controls (P=0.046). This effect was caused by the paranoid schizophrenia subgroup (P=0.018). Separate analysis of white matter revealed no diagnostic main group effect (P=0.846). However, the white matter of patients with paranoid schizophrenia contained more (mainly oligodendrocytic) S100B-positive glia as compared to residual schizophrenia (P=0.021). These effects were particularly pronounced in the DLPF brain area. CONCLUSION: Our study reveals distinct histological patterns of S100B immunoeactive glia in two schizophrenia subtypes. This may be indicative of a heterogenic pathophysiology or distinct compensatory abilities: Astro-/oligodendroglial activation may result in increased cellular S100B in paranoid schizophrenia. On the contrary, residual schizophrenia may be caused by white matter oligodendroglial damage or dysfunction, associated with a release of S100B into body fluids.

Demonstration of decreased activity of dorsal raphe nucleus neurons in depressed suicidal patients by the AgNOR staining method.

BACKGROUND: Suicide and depression are closely related yet distinct phenomena. In both these phenomena, research has focused on central serotonergic system disturbances. The dorsal raphe nucleus (DRN) is the main source of serotonergic innervation of limbic structures crucial for the regulation of emotionally influenced behaviour. METHODS: The study was carried out on paraffin-embedded brains from 23 depressed patients (12 suicides and 11 non-suicides) and 26 matched controls without mental disorders. The karyometric parameters of DRN neurons were evaluated by the AgNOR silver staining method. RESULTS: The significant effect of suicide on the nuclear area was found in the cumulative analysis of all DRN subnuclei (ANOVA, P=0.032). A decreased mean value of this parameter was observed in the suicides group versus controls (t-test, P=0.032). This effect was especially pronounced in the violent suicide victims (t-test, P=0.001), who also demonstrated a decreased AgNOR area versus controls (t-test, P=0.007). No significant effect of depression or polarity on AgNOR parameters was found. LIMITATIONS: A major limitation of this study is relatively small case number. A further limitation is given by the lack of data on drug exposure across the whole life span. CONCLUSION: Our findings suggest that hypoactivity of DRN neurons is a distinct phenomenon in depression, specific only for suicidal subgroup of depressed patients.

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.

Tyrosine hydroxylase immunoreactivity in the locus coeruleus is elevated in violent suicidal depressive patients.

Our postmortem study aimed to determine the impact of suicide on the number of noradrenergic neurons of the locus coeruleus (LC) in suicidal depressive patients. Noradrenergic neurons were shown by immunostaining tyrosine hydroxylase in the LC of 22 non-elderly patients with mood disorders compared to 21 age- and sex-matched normal controls. Eleven patients were suicide victims and the other eleven died of natural causes. Seven violent suicide victims revealed an increased number of tyrosine hydroxylase immunoreactive (TH-ir) neurons compared with non-violent suicide victims and controls. No difference was found between the number of TH-ir neurons in all suicidal patients and controls and between non-suicidal patients and controls. The differences of TH-immunoreactivity could neither be attributed to medication nor to the polarity of depressive disorder (unipolar/bipolar). The numbers of TH-ir neurons in suicidal patients correlated negatively with the mean doses of antidepressants. The study suggested a presynaptic noradrenergic dysregulation in the LC related to the level of self-aggression. Traditional antidepressants may, therefore, regulate noradrenergic activity of the LC in suicide patients, however, without demonstrating the suicide-preventing effect.

Evidence for a wide extra-astrocytic distribution of S100B in human brain.

BACKGROUND: S100B is considered an astrocytic in-situ marker and protein levels in cerebrospinal fluid (CSF) or serum are often used as biomarker for astrocytic damage or dysfunction. However, studies on S100B in the human brain are rare. Thus, the distribution of S100B was studied by immunohistochemistry in adult human brains to evaluate its cell-type specificity. RESULTS: Contrary to glial fibrillary acidic protein (GFAP), which selectively labels astrocytes and shows only faint ependymal immunopositivity, a less uniform staining pattern was seen in the case of S100B. Cells with astrocytic morphology were primarily stained by S100B in the human cortex, while only 20% (14-30%) or 14% (7-35%) of all immunopositive cells showed oligodendrocytic morphology in the dorsolateral prefrontal and temporal cortices, respectively. In the white matter, however, most immunostained cells resembled oligodendrocytes [frontal: 75% (57-85%); temporal: 73% (59-87%); parietal: 79% (62-89%); corpus callosum: 93% (86-97%)]. S100B was also found in ependymal cells, the choroid plexus epithelium, vascular endothelial cells, lymphocytes, and several neurones. Anti-myelin basic protein (MBP) immunolabelling showed an association of S100B with myelinated fibres, whereas GFAP double staining revealed a distinct subpopulation of cells with astrocytic morphology, which solely expressed S100B but not GFAP. Some of these cells showed co-localization of S100B and A2B5 and may be characterized as O2A glial progenitor cells. However, S100B was not detected in microglial cells, as revealed by double-immunolabelling with HLA-DR. CONCLUSION: S100B is localized in many neural cell-types and is less astrocyte-specific than GFAP. These are important results in order to avoid misinterpretation in the identification of normal and pathological cell types in situ and in clinical studies since S100B is continuously used as an astrocytic marker in animal models and various human diseases.

Immunohistochemical evidence for impaired neuregulin-1 signaling in the prefrontal cortex in schizophrenia and in unipolar depression.

In the central nervous system (CNS), neuregulin-1 (NRG-1) proteins function in neuronal migration, differentiation, and survival of oligodendrocytes. The NRG-1 gene codes for at least 15 different isoforms, which may be classified on the basis of their molecular structure. At least two different haplotypes of the NRG-1 gene may be associated with schizophrenia. An abnormal expression pattern of NRG-1 mRNA was found in the prefrontal cortex of schizophrenic patients in comparison to controls. We here show that the NRG-1alpha isoform is significantly reduced in white matter of the prefrontal cortex in schizophrenia but not in affective disorder. In the prefrontal gray matter, the density of NRG-1alpha expressing neurons was reduced in individuals with schizophrenia and in unipolar patients. We studied brains of 22 schizophrenics, 12 patients with affective disorders (7 unipolar and 5 bipolar), and 22 matched controls. NRG-1alpha immunoreactive material was detected with a polyclonal antiserum against the synthetic peptide from alpha-type EGF-like domain of human NRG. The demonstrated decreased number of NRG-1 immunoreactive neurons in the brains of schizophrenics and patients with unipolar depression points to an important role of this NRG-1alpha splice variant in neuropsychiatric disorders. Reduced NRG-1alpha protein concentrations were found in brains of schizophrenics after Western blot analysis. The diminished expression of NRG-1alpha strongly supports an early neurodevelopmental component to schizophrenia.

Dysregulation of GABAergic neurotransmission in mood disorders: a postmortem study.

Alterations of GABAergic neurotransmission are assumed to play a crucial role in the pathophysiology of mood disorders. Gamma-aminobutyric acid (GABA) acts via binding to A and B receptors, whereas the B receptor is G protein-coupled. Glutamic acid decarboxylase (GAD) is the key enzyme of GABA synthesis. Immunohistochemical staining of GAD 65/67-immunoreactive neurons was performed in dorsolateral prefrontal cortex, orbitofrontal cortex, anterior cingulate cortex, superior temporal cortex, hippocampus formation, and mediodorsal thalamus with consecutive determination of neuronal density in 20 brains of patients with mood disorders (P) and 19 controls (C). In the patients' group were 11 patients with bipolar disorder (BD) and 9 patients with major depressive disorder (MDD). The data were tested statistically using analysis of variance (ANOVA) and post hoc Tukey tests. ANOVA revealed significant differences among the groups (C, BD, MDD) in dorsolateral prefrontal cortex, orbitofrontal cortex, superior temporal cortex, and hippocampus. Post hoc tests demonstrated higher neuronal densities in unipolar patients compared with bipolar patients and controls in dorsolateral prefrontal cortex, superior temporal cortex, and hippocampus. In the orbitofrontal cortex, a higher neuronal density was found in bipolar and unipolar patients compared with controls. In mood disorder patients, dose equivalents of antidepressants given prior to death correlated positively with the neuronal density in superior temporal cortex and hippocampus. The current data on GAD 65/67 point to a dysregulation of the GABAergic system in mood disorders. Possibly, existing deficits of GABAergic neurotransmission will be compensated or overcompensated by antidepressants. Additionally, albeit speculative, an imbalance between GABA production and transport might be of relevance.

The changes of AgNOR parameters of anterior cingulate pyramidal neurons are region-specific in suicidal and non-suicidal depressive patients.

The anterior cingulate cortex (AC) is consistently implicated in the pathophysiology of depression. While suicide has been shown in previous reports to be closely related to depression, it is still a distinct phenomenon. The aim to differentiate between depression and suicide was approached by the karyometric analysis of AC pyramidal neurons. The study was performed on paraffin-embedded brains from 20 depressive patients (10 of whom had committed suicide) and 24 matched controls. The karyometric parameters of the layer III and V pyramidal neurons of the dorsal and ventral AC were evaluated bilaterally by Argyrophilic Nucleolar Organiser (AgNOR) silver staining method. Control-specific was the increased nuclear area in ontogenetically younger pyramidal neurons layer III in the left dorsal compared with ventral AC (Wilcoxon test, P<0.01). The decreased AgNOR number per nucleus in these cells in the right ventral AC was depression-specific compared with controls (t-test, P=0.047). On the other hand, the diffuse decrease in AgNOR ratio throughout pyramidal neurons on the left side was specific for suicidal depressive patients compared with non-suicidal patients and controls (ANOVA, P=0.028). The results suggest that regionally differentiated depression- and suicide-specific disturbed function of the most important AC output cells exists in depressive patients.

The changes in AgNOR parameters of dorsal raphe nucleus neurons are related to suicide.

Depression has been established as the main cause of suicide and the research has concentrated on disturbed central serotonergic system in both disorders. The dorsal raphe nucleus (DRN) of brain stem is the main source of serotonergic innervation of limbic structures fundamental in the regulation of emotionally influenced behavior. The study was carried out on paraffin-embedded brains from 10 depressive patients, among them 5 suicides and 5 non-suicides and 13 matched mentally healthy controls. The karyometric parameters of DRN neurons were evaluated by AgNOR (Argyrophilic Nucleolar Organizer) silver staining method. The significant effect of suicide on nuclear area and AgNOR-ratio found in the cumulative analysis of all DRN subnuclei could be relevant for forensic diagnostic. The results suggest DRN neurons hypoactivity specific for suicide. Whether observed phenomenon is a "common trait" existing also in other diagnostic groups of mental disorders remains an open question.

Differences in activation of the dorsal raphe nucleus depending on performance of suicide.

The serotonergic system has been implicated in the pathogenesis of mood disorders as well as in suicidal behavior. It is unknown, however, whether raphe neurons, which are mostly serotonergic, show altered activity in patients with mood disorders who complete suicide as compared to those without suicidal behavior. In order to measure cellular markers of serotonergic activity in the dorsal raphe nucleus in brains of 12 people with mood disorders and of 12 controls (C), stereological measurements were carried out of nucleolar organizer regions (AgNORs) and of serotonergic neuron numbers. Six patients died from suicide (S) and the other six patients died from natural causes (NS). Results were assessed using ANOVA and post hoc Tukey-HSD tests looking for effects of diagnostic group (S, NS, C). Results show that in the rostral subnuclei of the dorsal raphe there was a significant effect of diagnostic group on the ratios of the nucleolar organizer regions to nuclear area (NOR ratio) and a nearly significant effect on numbers of serotonergic neurons. Post hoc tests revealed larger values for those dependent variables in S compared to NS. Dose equivalents of antidepressants correlated positively with NOR ratios and numbers of serotonergic neurons in the rostral part of the dorsal raphe. In conclusion, the present data suggest that there are functional differences in the dorsal raphe of patients with mood disorders depending on suicidal behavior. Antidepressants appear to contribute to cellular activation in the rostral part of the dorsal raphe.

Calretinin and parvalbumin in schizophrenia and affective disorders: a mini-review, a perspective on the evolutionary role of calretinin in schizophrenia, and a preliminary post-mortem study of calretinin in the septal nuclei.

OBJECTIVE: The septal nuclei are important limbic regions that are involved in emotional behavior and connect to various brain regions such as the habenular complex. Both the septal nuclei and the habenular complex are involved in the pathology of schizophrenia and affective disorders. METHODS: We characterized the number and density of calretinin-immunoreactive neurons in the lateral, medial, and dorsal subregions of the septal nuclei in three groups of subjects: healthy control subjects (N = 6), patients with schizophrenia (N = 10), and patients with affective disorders (N = 6). RESULTS: Our mini-review of the combined role of calretinin and parvalbumin in schizophrenia and affective disorders summarizes 23 studies. We did not observe significant differences in the numbers of calretinin-immunoreactive neurons or neuronal densities in the lateral, medial, and dorsal septal nuclei of patients with schizophrenia or patients with affective disorders compared to healthy control subjects. CONCLUSIONS: Most post-mortem investigations of patients with schizophrenia have indicated significant abnormalities of parvalbumin-immunoreactive neurons in various brain regions including the hippocampus, the anterior cingulate cortex, and the prefrontal cortex in schizophrenia. This study also provides an explanation from an evolutionary perspective for why calretinin is affected in schizophrenia.

Increased densities of nitric oxide synthase expressing neurons in the temporal cortex and the hypothalamic paraventricular nucleus of polytoxicomanic heroin overdose victims: possible implications for heroin neurotoxicity.

Heroin is one of the most dangerous drugs of abuse, which may exert various neurotoxic actions on the brain (such as gray matter loss, neuronal apoptosis, mitochondrial dysfunction, synaptic defects, depression of adult neurogenensis, as well as development of spongiform leucoencephalopathy). Some of these toxic effects are probably mediated by the gas nitric oxide (NO). We studied by morphometric analysis the numerical density of neurons expressing neuronal nitric oxide synthase (nNOS) in cortical and hypothalamic areas of eight heroin overdose victims and nine matched controls. Heroin addicts showed significantly increased numerical densities of nNOS immunoreactive cells in the right temporal cortex and the left paraventricular nucleus. Remarkably, in heroin abusers, but not in controls, we observed not only immunostained interneurons, but also cortical pyramidal cells. Given that increased cellular expression of nNOS was accompanied by elevated NO generation in brains of heroin addicts, these elevated levels of NO might have contributed to some of the known toxic effects of heroin (for example, reduced adult neurogenesis, mitochondrial pathology or disturbances in synaptic functioning).