Regulation of cerebral blood flows by cholinergic fibers originating in the nucleus basalis of Meynert.

脑内胆碱能纤维起源于Meynert基底核(NBM)和隔核，分别投射到皮质和海马区，已有报道在阿尔茨海默病和老年人中发生变性。然而，这些胆碱能纤维的生理功能仍然不清楚。本实验利用麻醉的大鼠来检验这些纤维是否可以在大脑皮层和海马区作为血管扩张剂。局部脑血流量用激光多普勒血流仪或~(14)C-碘安替比林技术测量。电或化学刺激单侧NBM或内侧隔。刺激NBM和内侧隔区分别使皮质和海马区的脑血流量增加，但其他区域的脑血流量在刺激期间没有明显变化。静脉注射毒碱和烟酸阻滞剂(阿托品0.5 mg/kg和甲氨基酚2 mg/kg)可降低血管扩张反应。微透析法测得的皮层和海马区细胞外乙酰胆碱在刺激NBM和内侧隔时显著增加。总之，脑内胆碱能纤维的激活释放了皮层和海马区的乙酰胆碱，至少部分释放的乙酰胆碱导致血管扩张和这些区域脑血流量的增加。此时此刻，我想通过类比这个系统来推测，骨骼肌中的外周交感胆碱能血管扩张系统在骨骼肌开始收缩之前激活并向其供应足够的氧气和葡萄糖，这是有准备的目的。

Intracerebral cholinergic fibers originating in the nucleus basalis of Meynert (NBM) and septum, and projecting to the cortex and hippocampus, respectively, have been reported to degenerate in Alzheimer's disease as well as in aged people. However, physiological function of these cholinergic fibers have remained obscure. The present experiment was performed to examine whether these fibers can act as vasodilators in the cortex and hippocampus using anesthetized rats. Regional cerebral blood flow was measured by either laser Doppler flowmetry or ^<14>C iodoantipirine technique. The unilateral NBM or medial septum was stimulated electrically or chemically. Stimulations of the NBM and medial septum produced increases in cortical and hippocampal cerebral blood flows, respectively.But, cerebral blood flows in other regions did not change significantly during these stimulations. These vasodilative responses were reduced by intravenous administrations of muscarinic and nicotinic blocking agents (atropine, 0.5 mg/kg, and mecamylaminel 2 mg/kg). The extracellular acetylcholine in the cortex and hippocampus measured by the microdialysis technique was increased significantly during stimulations of the NBM and medial septum. In conclusion, activation of the intracerebral cholinergic fibers releases acetylcholine in the cortex and hippocampus, and at least some parts of the released acetylcholine result in vasodilation and increase in these regional cerebral blood flows. At this moment I would like to speculate by analogy of this system to the peripheral sympathetic cholinergic vasodilative system in skeletal muscles which activates and supplies sufficient oxygen and glucose to skeletal muscles, just before they start to contract, with a preparatory purpose.