Ragozzino M E, Pal S N, Unick K, Stefani M R, Gold P E
Department of Psychology, Gilmer Hall, University of Virginia, Charlottesville, Virginia 22903, USA.
J Neurosci. 1998 Feb 15;18(4):1595-601. doi: 10.1523/JNEUROSCI.18-04-01595.1998.
Recent evidence indicates that systemic glucose treatment enhances memory while producing a corresponding increase in hippocampal acetylcholine (ACh) output. The present experiments examined whether unilateral intrahippocampal infusions of glucose would enhance spontaneous alternation performance and whether there would be a corresponding increase in ACh output in the ipsilateral and contralateral hippocampus. Extracellular ACh was assessed in samples collected at 12 min intervals using in vivo microdialysis with HPLC with electrochemical detection. Twelve minutes after a unilateral infusion of artificial cerebrospinal fluid (CSF) or glucose (6.6 mM), rats were tested in a cross maze for spontaneous alternation behavior with concurrent microdialysis collection. In two experiments, glucose infusions significantly increased alternation scores (67.5 and 59%) compared with CSF controls (42.4 and 39.5%, respectively). In both experiments, behavioral testing resulted in increased ACh output in the hippocampus. Glucose administration at the time of alternation tests enhanced ACh output beyond that of behavioral testing alone both ipsilateral (+93.8%) and contralateral (+85%) to the infusion site, as compared with ACh output (+36.1% and +55.5%) of CSF controls. Glucose infusions did not affect hippocampal ACh output in rats kept in a holding chamber. These results suggest that glucose may enhance alternation scores by modulating ACh release. The findings also indicate that unilateral glucose infusions increase hippocampal ACh output both ipsilateral and contralateral to the site of injection. Furthermore, glucose increased ACh output only during maze testing, suggesting that specific behavioral demands, perhaps requiring activation of cholinergic neurons, determine the efficacy of glucose in modulating ACh release.
最近的证据表明，全身性葡萄糖治疗可增强记忆，同时使海马体乙酰胆碱（ACh）输出相应增加。本实验研究了单侧海马体内注入葡萄糖是否会增强自发交替行为表现，以及同侧和对侧海马体中的ACh输出是否会相应增加。使用带有电化学检测的高效液相色谱法（HPLC）的体内微透析技术，以12分钟的间隔收集样本，评估细胞外ACh。在单侧注入人工脑脊液（CSF）或葡萄糖（6.6 mM）12分钟后，对大鼠进行十字迷宫测试以检测自发交替行为，并同时进行微透析收集。在两项实验中，与CSF对照组（分别为42.4%和39.5%）相比，葡萄糖注入显著提高了交替得分（分别为67.5%和59%）。在两项实验中，行为测试均导致海马体中ACh输出增加。与CSF对照组的ACh输出（分别为+36.1%和+55.5%）相比，在交替测试时给予葡萄糖增强了ACh输出，在注入部位同侧（+93.8%）和对侧（+85%）均超过了单独行为测试时的增加幅度。葡萄糖注入对饲养笼中的大鼠海马体ACh输出没有影响。这些结果表明，葡萄糖可能通过调节ACh释放来提高交替得分。研究结果还表明，单侧葡萄糖注入会使注射部位同侧和对侧的海马体ACh输出均增加。此外，葡萄糖仅在迷宫测试期间增加ACh输出，这表明特定的行为需求，可能需要激活胆碱能神经元，决定了葡萄糖调节ACh释放的功效。
