Schröck H, Kuschinsky W
Department of Physiology, University of Heidelberg, F.R.G.
Brain Res. 1991 Apr 5;545(1-2):234-8. doi: 10.1016/0006-8993(91)91291-8.
Chronic infusion of nicotine has been shown to result (1) in an increase in nicotine binding sites in the brain and (2) in a distinct pattern of increases in local cerebral metabolic rate for glucose (CMRglc). The present study addresses two questions: (1) whether a one-day withdrawal of nicotine after a two-week exposure is long enough to restore local CMRglc to the preinfusion values and (2) whether an acute nicotine infusion after one day's withdrawal would influence local CMRglc. Chronic infusion of L-nicotine (12.5 micrograms/kg/min) was performed by osmotic minipumps. Local CMRglc was measured using the quantitative 2-deoxyglucose method in conscious rats. The following results were obtained: (1) a one-day withdrawal of nicotine after a two-week chronic infusion restores local CMRglc to a pattern which is close to the control pattern obtained without any nicotine infusion, and (2) an acute infusion of nicotine after a one-day withdrawal of a chronic nicotine infusion induces distinct increases in local CMRglc of several brain structures; these are essentially identical with structures which are activated during an acute nicotine infusion in otherwise untreated rats (no chronic infusion). The data indicate: (1) The main effects of chronic nicotine infusion on local CMRglc have disappeared after one day of nicotine withdrawal. (2) An acute load of nicotine in such nicotine-withdrawal rats has effects on local CMRglc which resemble those found in previously untreated rats during an acute nicotine infusion. (3) In contrast to most binding studies which have shown persisting increases in nicotine binding sites after one day's withdrawal of chronic nicotine, local CMRglc is restored to control values and can be again activated by an acute nicotine infusion.
（1）大脑中尼古丁结合位点增加；（2）局部脑葡萄糖代谢率（CMRglc）呈现出独特的增加模式。本研究探讨两个问题：（1）在两周暴露后停用尼古丁一天，是否足以使局部CMRglc恢复到输注前的值；（2）在停用一天后急性输注尼古丁是否会影响局部CMRglc。通过渗透微型泵进行L-尼古丁（12.5微克/千克/分钟）的长期输注。使用定量2-脱氧葡萄糖法在清醒大鼠中测量局部CMRglc。得到以下结果：（1）在两周长期输注后停用尼古丁一天，可使局部CMRglc恢复到接近未进行任何尼古丁输注时获得的对照模式；（2）在长期尼古丁输注停用一天后急性输注尼古丁，会导致几个脑结构的局部CMRglc明显增加；这些结构与在未进行慢性输注的未处理大鼠急性输注尼古丁期间被激活的结构基本相同。数据表明：（1）长期输注尼古丁对局部CMRglc的主要影响在尼古丁停用一天后消失。（2）在这种尼古丁戒断大鼠中急性加载尼古丁对局部CMRglc的影响，类似于在未处理大鼠急性输注尼古丁期间发现的影响。（3）与大多数结合研究不同，大多数结合研究表明在慢性尼古丁停用一天后尼古丁结合位点持续增加，局部CMRglc恢复到对照值，并且可再次被急性输注尼古丁激活。
