BMP10 expression in the adult rat central nervous system.

Bone morphogenetic protein 10 (BMP10), is a member of the transforming growth factor ß (TGFß) superfamily. Although BMP10 plays pivotal roles during development, including vascular development and cardiogenesis, little information is available for BMP10 expression in the central nervous system (CNS). We, thus, investigated BMP10 expression in the adult rat CNS using immunohistochemistry. BMP10 was intensely expressed in most neurons and their axons. Furthermore, we found that astrocytes and ependymal cells also express BMP10 protein. These data indicate that BMP10 is widely expressed throughout the adult CNS, and this abundant expression strongly supports the idea that BMP10 also plays important roles in the adult CNS.

BMP9 expression in the adult rat brain.

Bone morphogenetic protein 9 (BMP9), also known as growth differentiation factor 2 (GDF2), is a member of the transforming growth factor ß (TGF ß) superfamily. Although BMP9 plays pivotal roles during development, including angiogenesis, hematopoiesis, hepatogenesis, osteogenesis, and glucose metabolism, little information is available for BMP9 expression in the central nervous system (CNS). We, thus, investigated BMP9 expression in the adult rat CNS using immunohistochemistry. BMP9 was intensely expressed in most neurons and their axons. Furthermore, we found that oligodendrocytes and ependymal cells also express BMP9 protein. These data indicate that BMP9 is widely expressed throughout the adult CNS, and this abundant expression strongly supports the idea that BMP9 also plays important roles in the adult brain.

Decreased Proliferation in the Neurogenic Niche, Disorganized Neuroblast Migration, and Increased Oligodendrogenesis in Adult Netrin-5-Deficient Mice.

In the adult mouse brain, neurogenesis occurs mainly in the ventricular-subventricular zone (V-SVZ) and the subgranular zone of the hippocampal dentate gyrus. Neuroblasts generated in the V-SVZ migrate to the olfactory bulb via the rostral migratory stream (RMS) in response to guidance molecules, such as netrin-1. We previously showed that the related netrin-5 (NTN5) is expressed in Mash1-positive transit-amplifying cells and doublecortin-positive neuroblasts in the granule cell layer of the olfactory bulb, the RMS, and the subgranular zone of the adult mouse brain. However, the precise role of NTN5 in adult neurogenesis has not been investigated. In this study, we show that proliferation in the neurogenic niche is impaired in NTN5 knockout mice. The number of proliferating (EdU-labeled) cells in NTN5 KO mice was significantly lower in the V-SVZ, whereas the number of Ki67-positive proliferating cells was unchanged, suggesting a longer cell cycle and decreased cell division in NTN5 KO mice. The number of EdU-labeled cells in the RMS and olfactory bulb was unchanged. By contrast, the numbers of EdU-labeled cells in the cortex, basal ganglia/lateral septal nucleus, and corpus callosum/anterior commissure were increased, which largely represented oligodendrocyte lineage cells. Lastly, we found that chain migration in the RMS of NTN5 KO mice was disorganized. These findings suggest that NTN5 may play important roles in promoting proliferation in the V-SVZ niche, organizing proper chain migration in the RMS, and suppressing oligodendrogenesis in the brain.

Follistatin expression in the central nervous system of the adult rat.

Follistatin was initially cloned as a monomeric polypeptide that inhibits the release of follicle-stimulating hormone. Although follistatin also plays pivotal roles in skeletal muscle hypertrophy and immunoregulation in the epididymis, little information is available regarding follistatin function in the adult central nervous system (CNS). Hence, we investigated follistatin expression in the adult rat CNS using immunohistochemistry. Follistatin was intensely expressed in most neurons and their axons. Furthermore, oligodendrocytes, ependymal cells, and some astrocytes also expressed follistatin protein. These data indicate that follistatin is widely expressed throughout the adult CNS. The abundant expression of follistatin in the adult brain suggests that this protein plays important roles in the CNS.

BMP6 expression in the adult rat central nervous system.

BMP6, a member of the TGF-ß superfamily, is known to be involved in many diseases, such as Alzheimer's disease, suggesting that BMP6 plays pivotal roles in the central nervous system (CNS), however, there's no information about the distribution of BMP6 in the adult CNS. Therefore, we investigated BMP6 expression in the CNS using immunohistochemistry. BMP6 was intensely expressed in most neurons and their axons. Furthermore, we found that oligodendrocytes, astrocytes and ependymal cells also express BMP6 protein. These data indicate that BMP6 is widely expressed throughout the adult CNS, and its abundant expression in the adult brain strongly supports the idea that BMP6 plays important roles in the adult brain.

Myostatin expression in the adult rat central nervous system.

Myostatin (also called as growth and differentiation factor 8 or GDF8), a member of the transforming growth factor ß (TGF-ß) superfamily of secreted differentiation and growth factors, is a potent inhibitor of skeletal muscle mass in mammals. Although myostatin also plays pivotal roles in cardiac growth and metabolism, postnatal glucose metabolism and adipogenesis, little information is available for myostatin function in the adult central nervous system (CNS). We, thus, investigated myostatin expression in the adult rat CNS using immunohistochemistry. Myostatin was intensely expressed in most neurons and their axons. Furthermore, we found that oligodendrocytes, astrocytes and ependymal cells also express myostatin protein. These data indicate that myostatin is widely expressed throughout the adult CNS, and its abundant expression in the adult brain suggests the idea that myostatin plays important roles in the CNS.

GDF11 expression in the adult rat central nervous system.

Growth differentiation factor 11 (GDF11), also known as bone morphogenetic protein 11 (BMP11), is a member of the transforming growth factor ß (TGF-ß) superfamily. Although GDF11 plays pivotal roles during development, including anterior/posterior patterning, formation of the kidney, stomach, spleen and endocrine pancreas, little information is available for GDF11 expression in the adult central nervous system (CNS). We, thus, investigated GDF11 expression in the adult rat CNS using immunohistochemistry. GDF11 was intensely expressed in most neurons and their axons. Furthermore, we found that astrocytes and ependymal cells also express GDF11 protein. These data indicate that GDF11 is widely expressed throughout the adult CNS, and its abundant expression in the adult brain strongly supports the idea that GDF11 plays important roles in the adult brain.

Bone morphogenetic protein-4 and bone morphogenetic protein receptors expressions in the adult rat eye.

We investigated the expressions of bone morphogenetic protein-4 (BMP4) and its receptors, bone morphogenetic protein receptor IA (BMPRIA), bone morphogenetic protein receptor IB (BMPRIB) and bone morphogenetic protein receptor II (BMPRII) in the adult rat eye. Interesting differences in expression profile were observed between BMPRIA and BMPRIB in the retina. BMPRIA-like immunoreactivity (IR) was very intensely seen in the photoreceptor layer, while BMPRIB-IR was mainly observed in the other layers. In the cornea, BMP4, BMPRIA, BMPRIB and BMPRII-IRs were abundantly seen in the cell body of basal cells in the corneal epithelium, and endothelium. In the lens, BMP4, BMPRIA, BMPRIB and BMPRII-IRs were observed in epithelial cells, lens cortical fiber cells, however they were not seen in the capsule and the central region of the lens. In the iris and ciliary body, strong BMP4 and BMPRIB-IRs were observed in nonpigmented epithelium. These results suggest that different kinds of BMP signaling should be needed in different areas in the adult eye to keep the shapes, differentiation levels, and functions of various cells.

BMP7 expression in the adult rat brain.

Bone morphogenetic protein-7 (BMP7), a member of the transforming growth factor-ß (TGF-ß) superfamily, has various effects in many biological events. However, there is little information on BMP7 expression in the adult central nervous system (CNS). Therefore, we investigated BMP7 levels in the adult rat CNS using immunohistochemistry. Abundant BMP7 expression was seen in astrocytes throughout the CNS and strong BMP7 expression was also observed in neuropils of the gray matter. Furthermore, BMP7 expression was observed in several kinds of neurons, including oxytocin, dopaminergic and noradrenergic neurons. These data suggest that BMP7 is widely expressed throughout the adult CNS, and support the idea that BMP7 plays pivotal roles in the adult brain, as well as in the developing brain.

Chordin and noggin expression in the adult rat trigeminal nuclei.

Bone morphogenetic proteins (BMP) exert its biological functions by interacting with membrane bound receptors. However, functions of BMPs are also regulated in the extracellular space by secreted antagonistic regulators, such as chordin and noggin. Although the deep involvement of BMP signaling in the development and functions of the trigeminal nuclei has been postulated, little information is available for its expression in the trigeminal nuclei. We, thus, investigated chordin and noggin expression in the adult rat trigeminal nuclei using immunohistochemistry. Chordin and noggin were intensely expressed throughout the trigeminal nuclei. In addition, interesting differences are observed between chordin expression and noggin expression. For example, chordin prefers dendritic expression than noggin, suggesting that chordin is involved in the regulation of dendritic morphology and synaptic homeostasis. Furthermore, chordin and noggin were differentially expressed in the neuropil of the trigeminal nuclei. Since BMP signaling is known to play a pivotal role to make precise neural network, theses differences might be important to keep precise interneuronal connections by regulating local BMP signaling intensity in each region. Interestingly, we also detected chordin and noggin expression in axons of the trigeminal nerves. These data indicate that chordin and noggin play pivotal roles also in the adult trigeminal system.

BMP3 expression in the adult rat CNS.

Bone morphogenetic protein-3 (BMP3) is a very unique member of the TGF-ß superfamily, because it functions as an antagonist to both the canonical BMP and activin pathways and plays important roles in multiple biological events. Although BMP3 expression has been described in the early development of the kidney, intestine and bone, little information is available for BMP3 expression in the central nervous system (CNS). We, thus, investigated BMP3 expression in the adult rat CNS using immunohistochemistry. BMP3 was intensely expressed in most neurons and their axons. Furthermore, we found that astrocytes and ependymal cells also express BMP3 protein. These data indicate that BMP3 is widely expressed throughout the adult CNS, and its abundant expression in the adult brain strongly supports the idea that BMP3 plays important roles in the adult brain.

BMP2 expression in the adult rat brain.

Bone morphogenetic protein-2 (BMP2) is a member of the transforming growth factor-ß (TGF-ß) superfamily and plays important roles in multiple biological events. Although BMP2 expression has been well described in the early development of the central nervous system (CNS), little information is available on its expression in the adult CNS. We thus investigated BMP2 expression in the adult rat CNS by using immunohistochemistry. Here we show that BMP2 is widely expressed throughout the adult CNS. In addition, besides intense BMP2 expression in almost all neurons, we found BMP2 expression in astrocytes and ependymal cells. Interestingly, we found that the axons of olfactory sensory neurons express BMP2. In addition, in the glomerular layer, BMP2 was very strongly expressed in some glomeruli, whereas the other glomeruli were weakly stained, suggesting that the variations in BMP2 expression level in each glomerus might be cues for each axon to find its adequate target and to keep its identity. Furthermore, we compared the expression patterns of BMP2 and BMP4. Interestingly, BMP4 was preferentially expressed in the dendrites of several neurons, whereas BMP2 was basically not expressed in the dendrites; however, it was detected in the axons. This means that in a single neuron the localizations of BMP2 and BMP4 are differentially regulated. These data indicate that BMP2 is more widely expressed throughout the adult CNS than previously reported, and its continued abundant expression in the adult brain strongly supports the idea that BMP2 also plays pivotal roles in the adult brain.

Imaging of phosphatidylcholines in the adult rat brain using MALDI-TOF MS.

Phosphatidylcholines (PCs) are the most abundant constituents of lipid in the brain. PCs function as major structural components of cell membranes and as important sources for signaling molecules. In the brain, three kinds of PCs, dipalmitoyl PC, palmitoyloleoyl PC, and stearoyloleoyl PC have been reported to be major species. They have different chemical and biological characteristics depending on the length of alkyl chains and the degree of saturation, suggesting that the abundance of PCs might be important to keep specialized membrane structures in the brain, such as myelin and synaptic membranes. However, detailed imaging of PCs in the total rat brain has not done yet. Thus, using imaging technology by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), we investigated the total distribution of PC32:0, PC34:1, and PC36:1 in the rat brain. PC32:0 and PC34:1 were more abundantly observed in the gray matter areas than in the white matter areas throughout the central nervous system (CNS), while PC36:1 was evenly seen at low levels in both areas. In addition, we found that PC32:0 and PC34:1 were detected at very high levels in the granular layer of the olfactory bulb, piriform cortex, insular cortex, and molecular layer of the cerebellum, which are known for areas showing high neuronal plasticity. The present imaging data clearly show that various PCs are differentially distributed throughout the rat CNS, and suggest that these differential distributions of various PCs are necessary to keep normal brain functions.

Irradiation in adulthood as a new model of schizophrenia.

BACKGROUND: Epidemiological studies suggest that radiation exposure may be a potential risk factor for schizophrenia in adult humans. Here, we investigated whether adult irradiation in rats caused behavioral abnormalities relevant to schizophrenia. METHODOLOGY/PRINCIPAL FINDINGS: A total dose of 15-Gy irradiation in six fractionations during 3 weeks was exposed to the forebrain including the subventricular zone (SVZ) and subgranular zone (SGZ) with male rats in the prone position. Behavioral, immunohistochemical, and neurochemical studies were performed three months after fractionated ionizing irradiation. Three months after fractionated ionizing irradiation, the total numbers of BrdU-positive cells in both the SVZ and SGZ zones of irradiated rats were significantly lower than those of control (sham-irradiated) rats. Hyperactivity after administration of the dopaminergic agonist methamphetamine, but not the N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine, was significantly enhanced in the irradiated rats although spontaneous locomotion in the irradiated rats was significantly lower than that of controls. Behavioral abnormalities including auditory sensory gating deficits, social interaction deficits, and working memory deficits were observed in the irradiated rats. CONCLUSION/SIGNIFICANCE: The present study suggests that irradiation in adulthood caused behavioral abnormalities relevant to schizophrenia, and that reduction of adult neurogenesis by irradiation may be associated with schizophrenia-like behaviors in rats.

BMP4 expression in the developing rat retina.

We investigated the expression of bone morphogenetic protein-4 (BMP4) in the developing retina. At E19, we found very intense BMP4 immunoreactivity (IR) in the nerve fiber layer. At P1, the inner plexiform layer exhibited very strong BMP4-IR. Thereafter, abundant BMP4 expression was kept to the adult period. These results suggest that BMP4 plays pivotal roles in the retina not only in the early embryonic period but also in the late embryonic and postnatal periods, and even in the adult.

Bone morphogenetic protein-4 expression in the adult rat brain.

Bone morphogenetic protein-4 (BMP4) is a member of the transforming growth factor-beta (TGF-beta) superfamily and plays important roles in multiple biological events. Although BMP4 expression has been well described in the early development of the central nervous system (CNS), little information is available on its expression in the adult CNS. Therefore, we investigated BMP4 expression in the adult rat CNS by using immunohistochemistry. BMP4 is intensely expressed in most neurons and their dendrites. In addition, intense BMP4 expression was also observed in the neuropil of the gray matters where high plasticity is reported, such as the molecular layer of the cerebellum and the superficial layer of the superior colliculus. Furthermore, we found that astrocytes also express BMP4 protein. These data indicate that BMP4 is more widely expressed throughout the adult CNS than previously reported, and its continued abundant expression in the adult brain strongly supports the idea that BMP4 plays pivotal roles also in the adult brain.

Glycine cleavage system in neurogenic regions.

The glycine cleavage system (GCS) is the essential enzyme complex for degrading glycine and supplying 5,10-methylenetetrahydrofolate for DNA synthesis. Inherited deficiency of this system causes nonketotic hyperglycinemia, characterized by severe neurological symptoms and frequent association of brain malformations. Although high levels of glycine have been considered to cause the above-mentioned problems, the detailed pathogenesis of this disease is still unknown. Here we show that GCS is abundantly expressed in rat embryonic neural stem/progenitor cells in the neuroepithelium, and this expression is transmitted to the radial glia-astrocyte lineage, with prominence in postnatal neurogenic regions. These data indicate that GCS plays important roles in neurogenesis, and suggest that disturbance of neurogenesis induced by deficiency of GCS may be the main pathogenesis of nonketotic hyperglycinemia.

Essential role of endogenous tissue plasminogen activator through matrix metalloproteinase 9 induction and expression on heparin-produced cerebral hemorrhage after cerebral ischemia in mice.

Cerebral hemorrhage associated with antithrombotic and thrombolytic therapy in acute stroke continues to present a major clinical problem. Rupture of the cerebral microvasculature involves the degradation and remodeling of extracellular matrix. Here we demonstrated that the delayed administration of heparin 3 hours after photothrombotic middle cerebral artery occlusion (MCAO) caused cerebral hemorrhage in wild-type (WT) mice but not in tissue plasminogen activator (tPA)-deficient knockout (KO) mice. Heparin administration increased tPA activity and its mRNA expression at 6 and 12 hours after MCAO in the ischemic hemispheres of WT mice. The expression of tPA was enhanced in microglial cells in the ischemic border zone. We also observed an exacerbation of matrix metalloproteinase (MMP) 9 expression at the mRNA level and its conversion to an active form after heparin administration in the ischemic hemisphere in WT mice but not in tPA KO mice. The increased MMP 9 expression was localized in microglial cells and endothelial cells. These findings suggest that endogenous tPA, through the enhancement of MMP 9 expression and proteolytic activation, plays an essential role in the pathogenesis of heparin-produced cerebral hemorrhage. Targeting tPA, MMP 9, or both may provide a new approach for preventing cerebral hemorrhage associated with antithrombotic therapy for stroke in humans.

A novel secretory factor, Neurogenesin-1, provides neurogenic environmental cues for neural stem cells in the adult hippocampus.

Neurogenesis occurs in restricted regions in the adult mammalian brain, among which the neurogenesis in the hippocampal dentate gyrus plays the crucial role in learning and memory. To date, little is known about neurogenic cues, which result in the neuronal fate adoption of neural stem cells residing in neurogenic regions, especially neurogenic cues in adult hippocampal neurogenesis. In the present study, we show that hippocampal astrocytes and also dentate granule cells adjacent to neural stem cells secrete a newly cloned novel secretory factor, Neurogenesin-1. This protein contains three cysteine-rich domains and a unique sequence and contributes to neuronal differentiation of neural stem cells in the adult brain by preventing the adoption of a glial fate. Furthermore, the neurogenic activity detected in the hippocampal culture medium was markedly suppressed by the administration of an anti-Neurogenesin-1 antibody. These findings suggest endogenous mechanisms that induce adult hippocampal neurogenesis and propose an innovative treatment for the neurodegenerative diseases that cause loss of hippocampal neurons.

New role of delta2-glutamate receptors in AMPA receptor trafficking and cerebellar function.

Previous gene knockout studies have shown that the orphan glutamate receptor delta2 (GluRdelta2) is critically involved in synaptogenesis between parallel fibers and Purkinje cells during development. However, the precise function of GluRdelta2 and whether it is functional in the mature cerebellum remain unclear. To address these issues, we developed an antibody specific for the putative ligand-binding region of GluRdelta2, and application of this antibody to cultured Purkinje cells induced AMPA receptor endocytosis, attenuated synaptic transmission and abrogated long-term depression. Moreover, injection of this antibody into the subarachnoidal supracerebellar space of adult mice caused transient cerebellar dysfunction, such as ataxic gait and poor performance in the rotorod test. These results indicate that GluRdelta2 is involved in AMPA receptor trafficking and cerebellar function in adult mice.