Visualization of the change in pain by the autoradiography and calcium imaging in the brain and spinal cord

PSPA-4是一种丙烯酸（acroa）类似物，在低剂量时可减弱丙烯酸引起的异位性疼痛，在高剂量时可诱导异位性疼痛。体外放射自显影显示[11C] ppa -4特异性结合大鼠脑和脊髓，且这种结合被kainic酸明显取代。PSPA-4增加了对谷氨酸反应的培养背根神经节神经元细胞内Ca2+浓度，其浓度远高于盐酸盐。综上所述，PSPA-4通过不同于已知盐酸盐拮抗剂的结合位点在低剂量时减轻异位性疼痛，在高剂量时诱导异位性疼痛。为了可视化疼痛的变化，需要一种新的具有较强放射性的放射自显影类似物。PSPA-4的开发将使我们不仅对acroa的作用机制，而且对外周和中枢神经系统疼痛传递的认识有突破性的突破。

PSPA-4, an acromelic acid (Acro-A) analogue, attenuated the Acro-A-induced allodynia at low doses and induced allodynia at high doses. In vitro autoradiography, [11C]PSPA-4 was specifically bound to the rat brain and spinal cord, and the binding was significantly displaced by kainic acid. And, PSPA-4 increased intracellular Ca2+ concentration of cultured dorsal root ganglion neurons responding to glutamate, much higher than kainate in of them. Taken together, that PSPA-4 attenuated allodynia at low doses and induced allodynia at high doses via a binding site different from known kainate antagonists. In order to visualize the change of pain, a new analogue which has stronger radioactivity is necessary for in vitro autoradiography.The development of PSPA-4 will enable us to make a break through in the understanding of the action mechanism not only of Acro-A, but also of pain transmission in the periphery and central nervous system.