| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2006: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2005: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2004: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
1) Effects of CGRP on cytoplasmic Ca^<2+> mobilization and membrane potential
In human osteoblastic MG63 cells, CGRP (1-100 nM) induced a transient Ca^<2+> spike and a subsequent slow increment in cytoplasmic free Ca^<2+> concentrations ([Ca^<2+>]_i). The second phase was not observed in rat osteoblastic UMR106 cells. CGRP also induced plasma membrane hyperpolarization. This action was attenuated only approximately 50% by an antagonist of CGRP subtype I receptor (CGRP-R1), CGRP_<8-37>. These findings suggest that These CGRP actions are not solely mediated by known CGRP-R1 but also by other non-subtype I receptors.
2) Schild plot analysis of CGRP-induced cellular responses
In MG63 cells, the CGRP-induced cellular responses, such as cAMP production, p38-MAPK phosphorylation, and CREB phosphorylation, were identified to be mediated by the same single CGRP receptor subtype, probably CGRP-R1. In contrast, CGRP-induced ERK dephosphorylation was suggested to be mediated either by a single unknown subtype of CGRP receptor or by a combination of CGRP-R1 and a unknown receptor subtype(s).
3) Effects of adrenomedullin, calcitonin, and their specific antagonists on intracellular signaling pathways
In addition to MG63 cells, human periodontal ligament cells were employed here. Both adrenomedullin (ADM) and calcitonin (CT) at higher concentrations (1 μM) mimicked CGRP action, but their specific antagonists, such as ADM_<22-52> and CT_<8-32>, failed to significantly block CGRP action. These findings suggest that CGRP actions we have observed are not mediated either by ADM receptor or CT receptor, but by several CGRP-specific receptor subtypes.
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