| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2000: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1999: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Research Abstract |
Recently, we found a novel subtype of prostaglandin I_2 (PGI_2) receptor expressed in the central nervous system. (15R)-16m-Tolyl-17, 18, 19, 20-tetranorisocarbacyclin (15R-TIC) and 15-deoxy-TIC (150-TIC) are synthesized and demonstrated to be specific for this CNS-type PGI_2 receptor which we referred to as IP_2. These compounds show a quite low affinity to the pheripheral type of cloned PGI_2 receptor, and therefore have little effects on circulatory parameters. In the present study, we attempted to clarify the molecular nature and function of this IP_2. Quantitative autoradiographic mapping of IP_2 in the rat brain has been performed using tritiated 15R-TIC and 15D-TIC, and as a result IP_2 is distributed in a variety of brain regions, mostly in the gray matter (Watanabe et al., J.Neurochem., 1999). For the study on the molecular properties of IP_2, we developed several ligands for a photo-affinity labelling. By using tritiated fluoro-azido derivatives of 15R-TIC, the photo-affinity labelling was succeeded and the molecular mass of photo-affinity-labelled protein was around 30 kD.In the separate study, we succeeded to purify the binding protein (IP_2) after solubilization from the plasma membrane and a few steps of column chromatography including the affinity column. We then found the neuroprotective effect of these compounds in vitro in primary cultured hippocampal neurons, and their effects on in vivo model, i.e., a transient ischemic model of gerbils and the middle cerebral artery occlusion (MCAO)-reperfusion models of rats and crab-eating
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