Signal cording and target net work of spatial disorientation in the brain

以异食癖作为大鼠运动病的行为学指标，建立了大鼠运动病动物模型。老鼠不能呕吐，但异食癖，即摄入非营养物质，如高岭土（水合硅酸铝），是一种疾病反应行为，类似于呕吐。在2小时的2g超重力负荷后，大鼠吃了大量的高岭土，表明它们患有运动病。超重力诱导的高岭土摄入量被抑制美托咪胺，一种H1拮抗剂，但不是由zolantizine，一种H2拮抗剂。通过在体脑微透析测量，2小时2g超重负荷也短暂增加了大鼠下丘脑组胺的释放。结果表明，超重后中枢组胺能神经元系统的激活可能通过H1受体（H1R）诱导运动病的发生。2g超重力作用2h后，大鼠下丘脑H1R mRNA表达显著增加，提示超重力可诱导H1R表达上调。与先前的研究结果表明，超重力后组胺能神经元激活，本研究结果进一步表明，在运动病的发展中，H1传递放大。H1R的上调可能与运动病症状的形成有关，运动病症状先逐渐发展，然后迅速发展。

We have developed an animal model of motion sickness, using pica as a behavioral index of motion sickness in rats. Rats cannot vomit, but pica, the ingestion of non-nutritive substances such as kaolin (hydrated aluminum silicate), is an illness-response behavior, which is analogous to vomiting. After 2-hours load of 2g hypergravity, rats ate a significant amount of kaolin, indicating that they suffered from motion sickness. The hypergravity-induced kaolin intake was suppressed by mepyramine, an H1 antagonist, but not by zolantizine, an H2 antagonist. A 2-h load of 2g hypergravity also transiently increased the release of histamine in the rat hypothalamus measured by in vivo brain microdialysis. These findings suggested that the activation of the central histaminergic neuron systems after hypergravity induces motion sickness via H1 receptors (H1R).Then, to investigate changes in post-synaptic events in the development of motion sickness, gene expression of H1R in the rat hypothalamus was examined using a real-time PCR method after hypergravity. The expression of H1R mRNA in the rat hypothalamus was significantly increased after 2g hypergravity for 2 hours, indicating an up-regulation of H1R induced by hypergravity. Taken together with the previous finding demonstrating an activation of the histaminergic neurons after hypergravity, the present finding further indicate an amplification of the H1 transmission in the development of motion sickness,. The up-regulation of H1R may contribute to the built up characteristic of motion sickness symptoms, which developed gradually at first and then progressed rapidly.