Roles of cytokines and trophic factors on the plastic changes of dendritic morphology

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1.Effects of endogenous lectin and immunosuppressant FK506 on sensory neurons1)Galectin-1(Gal-1) is involved in a variety of functions, including neurite outgrowth. About 20% of DRG neurons showed intense Gal-1-immunoreactivity, and most of them were c-Ret-positive. Intrathecal administration of anti-rhGal-1 antibody significantly attenuated the mechanical hypersensitivity induced by peripheral nerve injury, suggesting that endogenous Gal-1 potentiates neuropathic pain.2)FK506 shows multiple actions on neurons, although precise mechanisms are obscure. We addressed if FK506 directly activates sensory neurons or not. Ca^<2+> on cultured rat DRG neurons revealed FK506-induced increase in intracellular Ca^<2+> in a subpopulation of small DRG neurons (3.1%). When DRGs from inflamed rats were used, the incidence increased to 7.4%. FK506 sensitive neurons also responded to capsaicin and bradykinin. In the nerve-skin preparation, FK506 enhanced neuronal discharges of single C-fibers that are r … More esponsive to heat and bradykinin, indicating that FK506 activates nociceptive C-fibers (submitted to a journal).2.Factors that regulate dendritic morphology of hippocampal neurons in chronically stressed animalsRepetitive restrain stress for 3 weeks was shown to induce dendritic atrophy of pyramical cells in the hippocampus. We investigated BDNF mRNA levels in the hippocampus, together with plasma glucocorliocid (CC) levels, GC receptors in the hippocampus/hypothalamus and 5-HT synthesis in the raphe nuclei, in these animals, and suggested that CC-and 5-HT-induced down regulation of BDNF synthesis in the hippocampus plays a pivotal role in the regulation of dendritic morphology (submitted to a journal).3.Roles of a new member of TNF receptor superfamily TROY on the development of nervous systemWe investigated the expression pattern of TROY mRNA in the developing mice brain. TROYmRNA was strongly expressed in the ventiicular zone and subventiicular zone, which contain neuronal and glial precursors during embryogenesis, indicating that TROY plays important roles in the development of nervous system. Less