Kaori Tano

HYPOXIA-INDUCED ASTROCYTES PROMOTE THE MIGRATION OF NEURAL PROGENITOR CELLS VIA VASCULAR ENDOTHELIAL FACTOR, STEM CELL FACTOR, STROMAL-DERIVED FACTOR-1α AND MONOCYTE CHEMOATTRACTANT PROTEIN-1 UPREGULATION IN VITRO

1 The aim of the present study was to examine if and how rat hypoxia‐induced astrocytes affect the migration of neural progenitor cells (NPC) and to investigate the expression patterns of some chemokines, such as vascular endothelial growth factor (VEGF), stem cell factor (SCF), stromal‐derived factor‐1α (SDF‐1α), fractalkine and monocyte chemoattractant protein‐1 (MCP‐1) in hypoxia‐induced astrocytes and their contribution to NPC migration in vitro. 2 Costar Transwell inserts were used for the chemotaxis assay and quantified changes in the chemokines mRNA for between 0 h and 24 h posthypoxia were tested using real‐time quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) analysis. The results showed that the chemotaxis of astrocyte cells exposed to hypoxia for 18 h reached a peak value, whereas the chemotaxis of astrocytes exposed to hypoxia for 24 h began to decrease compared with those exposed to hypoxia for 18 h. Hypoxia upregulated chemokine VEGF, SCF, SDF‐1α and MCP‐1 expression in a time‐dependent manner but downregulated fractalkine expression in astrocytes. In addition, the time points of the peak expressions for VEGF, SCF, SDF‐1α and MCP‐1 were similar to the time point of maximum NPC migration. 3 Specific inhibitors that block the binding of specific chemokines to its receptors were used for analysing the contribution of the chemokine to NPC migration. When VEGF, SCF, SDF‐1α and MCP‐1 were each inhibited independently, NPC migration was reduced. When they were inhibited together, NPC migration was obviously inhibited compared with both the control and single‐block cultures, which implies that the migratory effect of hypoxia‐induced astrocytes was synergetic by several chemokines. 4 In conclusion, we demonstrated the time‐dependent manner of NPC migration promotion by hypoxia‐induced astrocytes. We also provide evidence that soluble factors, such as VEGF, SCF, SDF‐1α and MCP‐1, released from astrocytes, direct the migration of NPC under hypoxic circumstances. Given that astrocytes were activated to all hypoxia–ischaemia diseases, these results indicate an important role for astrocytes in directing NPC replacement therapy in the central nervous system.

Nonexploratory movement and behavioral alterations in a thalidomide or valproic acid-induced autism model rat

Autism is a behaviorally characterized disorder with impairments in social interactions, as well as stereotyped, repetitive patterns of behaviors and interests. Exposure of rat fetuses to thalidomide (THAL) or valproic acid (VPA) on the ninth day of gestation has been reported as a useful model for human autism. We have shown that early serotonergic neural development is disrupted in these rats. In the current study, we used a radial maze and open field experimental paradigm to investigate whether these rats present behavioral and/or learning aberrations. THAL (500mg/kg), VPA (800mg/kg), or vehicle was administered orally to E9 pregnant rats at 7-10 weeks of age. Although the mean number of correct and incorrect arm choices in the initial eight arm choices did not differ between control and teratogen-exposed groups, achievement of learning (seven or eight consecutive correct choices for 3 consecutive days for individual rats) seemed to be impaired in teratogen-exposed groups. Interestingly, average time to explore the maze task was shorter in the teratogen-exposed groups, indicating that correct choice might be due to mere coincidence (i.e., nonexploratory movement). Unexpectedly, no significant differences were observed in social interaction in these rats. These results indicate that prenatal exposure to THAL and VPA might alter behavior in a manner that is, in part, consistent with human autism.

Manserin, a secretogranin II-derived peptide, distributes in the rat endocrine pancreas colocalized with islet-cell specific manner

Manserin is a recently characterized 40-amino acid neuropeptide derived from secretogranin II, a protein belonging to the chromogranin family. Although the physiological roles of manserin have not been elucidated to date, manserin has been shown to distribute in not only the brain but also the endocrine system such as the pituitary and adrenal glands, suggesting its role in the endocrine system. The present study aimed to explore the occurrence and distribution of manserin in the rat pancreas using an immunohistochemical technique with a polyclonal antibody against rat manserin. Immunoreactivity for manserin was readily detected in almost whole islets of Langerhans whereas not at all in the exocrine pancreas. Manserin-expressing cells were not colocalized with the glucagon-secreting cells (α cells), whereas they colocalized with insulin-secreting cells (β cells) and somatostatin-secreting cells (δ cells), although their intracellular distribution was different. These results indicate that manserin, occurring in the endocrine pancreas, may have a potential role in the endocrine system.

Immunohistochemical Localization of Manserin, a Novel Neuropeptide Derived from Secretogranin II, in Rat Adrenal Gland, and its Upregulation by Physical Stress

We recently identified a novel 40-amino acid neuropeptide designated manserin from the rat brain (Yajima in NeuroReport 15: 1755–1759, 2004). Manserin is highly expressed in pituitary and hypothalamic nuclei, which suggests that it plays a role in the endocrine system. In this study, we employed immunohistochemical methods to investigate the presence of manserin in rat adrenal glands, as well as its regulation by physical stress. Immunohistochemical analysis using anti-manserin antibody showed that manserin is present in the rat adrenal medulla but not in the cortex. When the colocalization of manserin and phenylethanolamine N-methyltransferase (PNMT), an epinephrine-synthesizing enzyme, was examined, virtually all PNMT-positive cells expressed manserin. Interestingly, the immunoreactivity of manserin was significantly increased when the rats were exposed to water-immersion restraint stress. These results demonstrate for the first time that adrenal manserin, a novel neuropeptide, may have a potential physiological role under stress-inducing conditions.

Positron Emission Tomography Analysis of the Analgesic Effects of Acupuncture in Rhesus Monkeys

The purpose of this study was to examine whether pain-induced brain activation was suppressed by acupuncture analgesia. We investigated the suppression of the pain-induced neuronal activation in specific brain areas of three male rhesus monkeys (aged four years old) using positron emission tomography (PET), in which changes in the regional cerebral blood flow (rCBF) were examined as an index of the neuronal activation. The brain areas such as the thalamus, insula and anterior cingulate cortex were activated by heating the tail of monkeys in 47 degrees C water compared to the heating at 37 degrees C. Those activations were suppressed by electroacupuncture (EA) with a 2 sec alteration of the frequency of 4 Hz/60 Hz at the right ST36 (the upper anterior tibial muscle) and the right LI4 (the back palm between the first and second metacarpal) acupoints. Meanwhile, this EA analgesic effect was confirmed by prolonging the tail withdrawal latencies from hot water in the temperature range from 45 to 50 degrees C.These brain areas were corresponded to the pain-related areas as reported in previous studies. In conclusion, we were able to visualize the acupuncture analgesia in the CNS. We also detected the brain areas activated or inactivated by acupuncture. The areas that responded to acupuncture stimulation at 47 degrees C water were different from the regions at 37 degrees C. We consider that this difference in the response to acupuncture may support the variation of the clinical efficacy of acupuncture in patients bearing pain or other disorders.

Secretogranin II and its Derivative Peptide, Manserin, are Differentially Localized in Purkinje Cells and Unipolar Brush Cells in the Rat Cerebellum

The cerebellum has long been recognized as the primary center of motor coordination in the central nervous system. Cerebellar neuropeptides have been postulated to be involved in such motor coordination, though this role is not fully understood. We herein investigated the localization of novel neuropeptide, “manserin” in the adult rat cerebellum. Punctate signals of manserin immunoreactivity were observed in the granular layer of the rat cerebellum. Manserin signals were also observed in the fibers and fiber terminals in the granular layer as well as the molecular layer. Manserin did not localize in Purkinje cells. Interestingly, cerebellar manserin was preferentially colocalized with unipolar brush cells, a class of excitatory granular layer interneuron, which are known to be involved in vestibullocerebellar functions. These results indicate that manserin plays pivotal roles in the cerebellar functions.