下行性の筋緊張制御における脊髄のセロトニン1Aおよび2受容体の役割

来源于中缝核的血清素能下降神经元支配脊髓运动神经元，控制肌肉张力和运动。然而，血清素受体的亚型和具体的作用机制尚不清楚。在本研究中，我们通过测量成年大鼠的脊髓反射电位和5-羟色胺释放来研究以下内容。1.8- oh - dpat被广泛用作5-HT1A受体的激动剂。在这项研究中，我们发现R-和s -异构体通过不同类型的受体促进脊髓运动活动。在脊髓水平，r -异构体通过5- ht1a - 2以外的受体抑制单突触反射。我们发现环苯扎林和环苯扎林的类似物阿米替林和环庚啶阻断脊髓中的5-HT2受体，从而抑制单突触反射。5-HT2受体参与了血清素能系统的运动刺激作用。采用脊髓蛛网膜下腔灌注法测定血清素能神经元下降末端释放的血清素。阻断脊髓5-HT2受体的阿米替林没有增加血清素。从这个结果来看，阿米替林对5-羟色胺的摄取抑制作用被认为弱于5-HT2受体阻断作用。安定具有肌肉松弛作用，能减少血清素的释放。这些结果表明，脊髓运动系统是由下降的血清素能系统促进，特别是通过5-HT2受体。另一方面，提示除5-HT1A外，5-HT受体对脊髓运动系统有抑制作用。

Descending serotonergic neurons originated from the Raphe nuclei innervate spinal motoneurons, and control muscle tone and locomotion. However, the subtypes of the serotonergic receptors and the detailed mechanisms of action are still unclear. In the present study, we studied the followings using the measurement of spinal reflex potentials and serotonin release from the spinal cord in adult rats.1.8-OH-DPAT is widely used as an agonist for 5-HT1A receptor. In this study, we showed that the R- and S-isomers facilitate the spinal motor activity via different types of receptors. At the spinal cord level, the R-isomer depressed the monosynaptic reflex via receptors other than 5-HT1A.2.We showed that cyclobenzaprine, and amitriptyline and cyproheptadine, analogs of cyclobenzaprine blocked the 5-HT2 receptors in the spinal cord, and consequently depressed the monosynaptic reflexes. Involvement of 5-HT2 receptors in motor stimulatory role of serotonergic systems was elucidated.3.Serotonin released from the terminals of descending serotonergic neurons was measured using spinal subarachnoid space perfusion methods. Amitriptyline which blocks 5-HT2 receptors in the spinal cord did not increase serotonin. From this result, uptake inhibitory action of amitriptyline to serotonin was considered to be weaker than 5-HT2 receptor blocking action. Diazepam, which has muscle relaxant action, reduced the release of serotonin.These results suggest that spinal motor systems are facilitated by descending serotonergic systems, especially via 5-HT2 receptors. On the other hand, it was suggested that 5-HT receptors other than 5-HT1A inhibited spinal motor systems.