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目的大脑内胆固醇主要由自身合成且不易透过血脑屏障。因此,将脑内胆固醇转化成更易通过血脑屏障的24-羟胆固醇是保证其在脑内外转运动态平衡的关键。该转化过程主要依赖胆固醇24-羟化酶(cholesterol 24-hydroxylase)的作用来完成。本研究旨在探讨胆固醇24-羟化酶在猴脑中的表达。方法利用免疫组织化学技术观察胆固醇24-羟化酶在猴脑中的表达,并用光学显微镜和电子显微镜观察其表达部位。结果胆固醇24-羟化酶在大脑皮质、海马、杏仁核、Meynert基底核、纹状体以及小脑皮质的Purkinje神经元有中等强度的染色,且主要表达于神经元和神经纤维网。在丘脑、苍白球和脑干区,胆固醇24-羟化酶染色较浅。电子显微镜观察到胆固醇24-羟化酶表达在神经元轴突末端。结论大脑内胆固醇转运的主要场所是大脑投射神经元。此外,神经元轴突末端对维持脑胆固醇代谢平衡起关键作用。
Objective Cholesterol in the brain mainly by its own synthesis and difficult to penetrate the blood-brain barrier. Therefore, the conversion of intracerebral cholesterol into 24-hydroxycholesterol, which is more easily cross the blood-brain barrier, is the key to ensuring the homeostasis of intracellular and extracellular transport. This conversion is mainly dependent on the action of cholesterol 24-hydroxylase. This study aimed to investigate the expression of cholesterol 24-hydroxylase in monkey brain. Methods Immunohistochemistry was used to observe the expression of cholesterol 24-hydroxylase in monkey brain. The expression of cholesterol 24-hydroxylase was observed by light microscope and electron microscope. Results Cholesterol 24-hydroxylase was moderately stained in Purkinje neurons in the cerebral cortex, hippocampus, amygdala, basal nucleus of Meynert, striatum and cerebellum and was mainly expressed in neurons and neural network. In the thalamus, globus pallidus and brain stem area, cholesterol 24-hydroxylase staining lighter. Electron microscopy showed cholesterol 24-hydroxylase expression at the neuronal axon terminals. Conclusion The main site of intracerebral cholesterol transport is the neurons projecting from the brain. In addition, neuronal axon ends play a key role in maintaining brain cholesterol metabolism balance.