Brain serotonin and angiotensin II systems in migraine

描述(由申请人提供) 长期目标。脑内5-羟色胺(5-HT)系统在脑血管和神经内分泌调控中起着重要作用。这些系统被认为与偏头痛有关。偏头痛是一种低5-羟色胺综合征，发作可能是由作用于致敏受体的大量5-羟色胺释放引发的。这一建议将阐明5-羟色胺神经传递减少的现象与脑血管和神经内分泌反应改变之间的关系。重点将放在最近涉及偏头痛发病机制和/或预防治疗的5-羟色胺受体(5-HT1a、5-HTT、5-HT2s和5-HT2C)上。作为下丘脑-垂体-肾上腺(HPA)轴的关键激活剂，脑血管紧张素II(Ang II)系统的作用将被讨论。该提案旨在阐明偏头痛的病理生理机制，以及偏头痛预防性药物5-羟色胺和血管紧张素II的作用机制。明确的目标。以下假设将受到挑战：1)脑中5-羟色胺传递的减少将导致脑血管和HPA轴中5-羟色胺受体亚型的敏化和/或上调；以这些受体为靶点的偏头痛预防化合物的治疗将恢复5-羟色胺受体的功能和/或表达。这可能是偏头痛预防药物筛选的有用动物模型。2)对应激的反应，包括脑血管紧张素II和HPA系统的顺序激活，将导致脑组织5-羟色胺水平下降，5-羟色胺受体上调，和/或对5-羟色胺受体激活的神经内分泌和脑血管反应增强；用血管紧张素II合成抑制剂治疗将恢复5-羟色胺能功能。设计。1)5-羟色胺激动剂对Wistar大鼠的脑血管和神经内分泌反应，以及5-羟色胺受体在脑血管和HPA轴中的表达，将在对照组和5-羟色胺耗竭的Wistar大鼠中进行测定。偏头痛预防性5-羟色胺拮抗剂的长期治疗是否能恢复5-羟色胺受体的功能和/或表达将被确定。2)测定对照组和应激(急、慢性隔离束缚)Wistar大鼠脑内5-羟色胺含量、HPA轴5-羟色胺受体的表达以及神经内分泌和脑血管反应。通过血管紧张素转换酶抑制剂赖诺普利(一种偏头痛预防药物)的慢性治疗，将试图逆转应激诱导的这些变量的变化。体内脑血管反应性将通过激光多普勒血流仪(皮质血流量)和4-碘-[N-甲基-14C]-安替比林法(局部脑血流量)进行评估。体外脑血管反应性将用动脉造影室系统进行分析。激素反应(ACTH、皮质酮和催乳素)将通过放射免疫法测定血样，5-羟色胺受体的表达将通过定量受体放射自显影在组织切片中测定。脑匀浆中5-羟色胺的含量将用高效液相色谱法测定。

DESCRIPTION (provided by applicant) Long-term objectives. The brain serotonin (5-HT) system plays an important role in cerebrovascular and neuroendocrine control. These systems have been implicated in migraine. Migraine is a low 5-HT syndrome and attacks may be triggered by a massive release of 5-HT acting on sensitized receptors. This proposal will elucidate the association between the phenomena of decreased 5-HT neurotransmission and altered cerebrovascular and neuroendocrine responsiveness. Focus will be on 5-HT receptors recently implicated in migraine pathogenesis and/or prophylactic treatment (5-HT1A, 5-HTT, 5-HT2s and 5-HT2c). As a key activator of the hypothalamic-pituitary-adrenal (HPA) axis, the role of the brain angiotensin II (Ang II) system will be addressed. The proposal intends to shed light into the pathophysiological mechanisms of migraine, and the mechanism of action of migraine prophylactic 5-HT and Ang II drugs. Specific aims. The following hypotheses will be challenged: 1) A decreased 5-HT transmission in the brain will cause sensitization and/or up-regulation of 5-HT receptor subtypes in the cerebral vasculature and the HPA axis; treatment with a migraine prophylactic compound that target these receptors will restore 5-HT receptor function and/or expression. This may be a useful animal model for drug screening in migraine prophylaxis. 2) The response to stress, which involves sequential activation of the brain Ang II and the HPA systems, will lead to decreased brain 5-HT levels, up-regulation of 5-HT receptors, and/or amplified neuroendocrine and cerebrovascular responses to 5-HT receptor activation; treatment with an inhibitor of Ang II synthesis will restore serotonergic function. Design. 1) Cerebrovascular and neuroendocrine responses to 5-HT agonists, and expression of 5-HT receptors in the cerebral vasculature and the HPA axis, will be determined in control and 5-HT-depleted Wistar rats. It will be determined whether chronic treatment with a migraine prophylactic 5-HT antagonist restore 5-HT receptor function and/or expression. 2) Brain 5-HT content, expression of 5-HT receptors in the HPA axis, and neuroendocrine and cerebrovascular responses will be determined in control and stressed (acute and chronic isolation and restraint) Wistar rats. Reversal of stress-induced changes in these variables will be attempted by chronic treatment with the angiotensin-converting enzyme inhibitor, lisinopril (i.e. a migraine prophylactic agent). In vivo cerebrovascular reactivity will be assessed by laser- Doppler flowmetry (cortical blood flow) and the 4-iodo-[N-methyl-14C]-antipyrine method (regional cerebral blood flow). In vitro cerebrovascular reactivity will be analyzed with an arteriographic chamber system. The hormonal response (ACTH, corticosterone and prolactin) will be measured by radioimmuno assay in blood samples and 5-HT receptor expression will be determined by quantitative receptor autoradiography in tissue sections. 5-HT content will be measured by HPLC in brain homogenates.