Klein J, Köppen A, Löffelholz K
Department of Pharmacology, University of Mainz, F.R.G.
J Neurochem. 1991 Aug;57(2):370-5. doi: 10.1111/j.1471-4159.1991.tb03762.x.
In order to elucidate the regulation of the levels of free choline in the brain, we investigated the influence of chronic and acute choline administration on choline levels in blood, CSF, and brain of the rat and on net movements of choline into and out of the brain as calculated from the arteriovenous differences of choline across the brain. Dietary choline supplementation led to an increase in plasma choline levels of 50% and to an increase in the net release of choline from the brain as compared to a matched group of animals which were kept on a standard diet and exhibited identical arterial plasma levels. Moreover, the choline concentration in the CSF and brain tissue was doubled. In the same rats, the injection of 60 mg/kg choline chloride did not lead to an additional increase of the brain choline levels, whereas in control animals choline injection caused a significant increase; however, this increase in no case surpassed the levels caused by chronic choline supplementation. The net uptake of choline after acute choline administration was strongly reduced in the high-choline group (from 418 to 158 nmol/g). Both diet groups metabolized the bulk (greater than 96%) of newly taken up choline rapidly. The results indicate that choline supplementation markedly attenuates the rise of free choline in the brain that is observed after acute choline administration. The rapid metabolic choline clearance was not reduced by dietary choline load. We conclude that the brain is protected from excess choline by rapid metabolism, as well as by adaptive, diet-induced changes of the net uptake and release of choline.
为了阐明大脑中游离胆碱水平的调节机制，我们研究了长期和急性给予胆碱对大鼠血液、脑脊液和大脑中胆碱水平的影响，以及根据大脑动静脉胆碱差异计算得出的胆碱进出大脑的净移动情况。与一组食用标准饮食且动脉血浆水平相同的对照动物相比，膳食补充胆碱导致血浆胆碱水平升高50%，大脑中胆碱的净释放增加。此外，脑脊液和脑组织中的胆碱浓度增加了一倍。在同一批大鼠中，注射60mg/kg氯化胆碱并未导致大脑胆碱水平进一步升高，而在对照动物中，注射胆碱则导致显著升高；然而，这种升高在任何情况下都未超过长期补充胆碱所导致的水平。高胆碱组急性给予胆碱后胆碱的净摄取量大幅降低（从418降至158nmol/g）。两个饮食组都迅速代谢了大部分（超过96%）新摄取的胆碱。结果表明，补充胆碱可显著减弱急性给予胆碱后大脑中游离胆碱的升高。膳食胆碱负荷并未降低胆碱的快速代谢清除率。我们得出结论，大脑通过快速代谢以及膳食诱导的胆碱净摄取和释放的适应性变化来防止胆碱过量。
