The present study aimed at characterizing the anatomical and subcellular localization of cytoglobin (Cygb) and neuroglobin (Ngb) in the mouse brain by use of in situ hybridisation, immunohistochemistry and immunoelectron microscopy. Cygb and Ngb were only found in distinct brain areas and often in the same areas. We found intense staining in the piriform cortex, amygdala, hypothalamus (medial preoptic area, supra chiasmatic nucleus, lateral hypothalamus (LH), ventromedial hypothalamic nucleus, and the arcuate nucleus, habenular nuclei, laterodorsal tegmental nucleus (LDTg), pedunculopontine tegmental nucleus (PPTg), locus coeruleus, nucleus of the solitary tract and the spinal trigeminal nucleus. In addition Cygb is found in the hippocampus, the reticular thalamic nucleus, and the dorsal raphe nucleus; Ngb is found in the sub parabrachial nucleus. Co-localization of Cygb and Ngb is mainly observed in the LDTg and PPTg. Cygb and Ngb were found in cytoplasm, along neurotubuli, in mitochondria and in the nucleus by use of immunoelectron microscopy. Most neuronal nitric oxide synthase (nNOS)-positive neurons were found to co-localize Cygb, although not all nNOS neurones contain Cygb. Ngb co-localize with almost all orexin neurons in the LH. In conclusion the distribution of Cygb and Ngb seems much more restricted and coherent than previously reported. We believe other functions than pure oxygen buffers and neuroprotectants should be considered. The anatomical data indicate a role in NO signalling for Cygb and involvement in sleep-wake cycling for Cygb and Ngb.

Many studies suggest that the hippocampus is involved in the pathophysiology of psychiatric disorders, especially major depressive disorder (MDD) and schizophrenia. Especially, in vivo imaging studies indicate that the volume of hippocampus may be reduced in both disorders. Moreover, suicide may have a unique neurobiology. The aim of the present study is to investigate if depression, schizophrenia or suicide is associated with reduced postmortem volume of the hippocampal formation and/or changes in the numbers of neurons and/or glial cells in the different subregions of the hippocampus. We studied postmortem brain samples from 10 subjects with schizophrenia, 8 subjects with major depression, 11 suicide subjects with a history of depressive disorder, and 10 control subjects with no history of psychiatric or neurological diseases. The total volume and numbers of neurons and glial cells were estimated for the main hippocampal subregions using design-unbiased stereological techniques. We found the total volume and total numbers of neurons and glial cells similarly reduced by approximately 20% to 35% in depression and schizophrenia subjects relative to control subjects across all hippocampal regions. In suicide subjects, we only found increased neuron number in CA2/3 subregion. The volume and number of cells are reduced in depression and schizophrenia subjects relative to control subjects across all hippocampal regions. Our findings imply that the hippocampus may be a common site of pathophysiology in depression and schizophrenia. Community living suicide subjects seem to differ in hippocampal neurobiology compared to hospitalized subjects dying with MDD without suicide.

Prolonged stress has been associated with altered synaptic plasticity but little is known about the molecular components and mechanisms involved in the stress response. In this study, we examined the effect of chronic restraint stress (CRS) on the expression of genes associated with synaptic vesicle exocytosis in rat prefrontal cortex and hippocampus. Rats were stressed daily using a 21day restraint stress paradigm, with durations of half an hour or 6h. RNA and protein were extracted from the same tissue sample and used for real-time quantitative polymerase chain reaction (real-time qPCR) and immunoblotting, respectively. Focusing on the SNARE complex, we investigated the expression of the SNARE core components syntaxin 1A, SNAP-25, and VAMP2 at both transcriptional and protein levels. In addition, the expression of 10 SNARE regulatory proteins was investigated at the transcriptional level. Overall, the prefrontal cortex was more sensitive to CRS compared to the hippocampus. In prefrontal cortex, CRS induced increased mRNA levels of VAMP2, VAMP1, syntaxin 1A, snapin, synaptotagmins I and III, and synapsins I and II, whereas SNAP-25 was down-regulated after CRS. Immunoblotting demonstrated equivalent changes in protein levels of VAMP2, syntaxin 1A, and SNAP-25. In hippocampus, we found increased mRNA levels of VAMP2 and SNAP-29 and a decrease in VAMP1 levels. Immunoblotting revealed decreased VAMP2 protein levels despite increased mRNA levels. Changes in the expression of synaptic proteins may accompany or contribute to the morphological, functional, and behavioral changes observed in experimental models of stress and may have relevance to the pathophysiology of stress-related disorders.