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目的研究中脑导水管周围灰质(PAG)在血管源性头痛如偏头痛涉及的伤害觉信息的传递中的作用。方法以雄性SD大鼠(体重为220~250g)为实验对象,在手术暴露其上矢状窦(SSS)后电刺激SSS区硬脑膜制作血管性头痛的动物模型;应用免疫组织化学染色技术,观察中脑PAG原癌基因蛋白质c-fos(Fos)和一氧化氮合酶(NOS)表达的变化。结果Fos免疫反应阳性神经元和NOS免疫反应阳性神经元主要位于中脑PAG的腹外侧区,阳性细胞数头侧至尾侧逐渐增多。空白对照组、假手术对照组、刺激组每张切片的Fos阳性神经元数分别为7.2±4.2、13.6±4.3、76.0±12.3;NOS阳性神经元数分别为35.0±3.5、42.3±4.2、162.0±11.6。结论刺激大鼠SSS区硬脑膜可激活PAG,提示PAG不但参与对于伤害性感觉信息传入后的下行调节,还通过上行投射纤维与疼痛中枢丘脑发生联系。PAG可能参与血管源性头痛如偏头痛的痛觉中枢调控。
Objective To investigate the role of midbrain periaqueductal gray (PAG) in the transmission of nociceptive information related to vasogenic headache such as migraine. Methods Male Sprague-Dawley rats weighing 220-250 g were used to establish the animal models of vascular headache by electrical stimulation of the superior sagittal sinus (SSS) in the SSS area. The immunohistochemical staining To observe the changes of protein expression of c-fos (Fos) and nitric oxide synthase (NOS) in midbrain PAG. Results Fos immunoreactive neurons and NOS immunoreactive neurons mainly located in the ventral region of midbrain PAG, and the number of positive cells gradually increased from head to tail. The numbers of Fos positive neurons per slice in the blank control group, sham operation control group and stimulation group were 7.2 ± 4.2, 13.6 ± 4.3, 76.0 ± 12.3 respectively; the numbers of NOS positive neurons were 35.0 ± 3.5, 42.3 ± 4.2, 162.0 ± 11.6. CONCLUSIONS: Stimulation of PAG in the dural surface of SSS rats suggests that PAG not only participates in down-regulation of nociception sensory information but also associates with pain central thalamus via up-projection fibers. PAG may be involved in the pain-center regulation of vasogenic headache such as migraine.