一种新的M1受体激动剂对老年小鼠学习记忆和突触可塑性的影响

目的：已有的研究表明乙酰胆碱的M1受体参与了中枢的学习记忆，M1受体的激动剂一占诺美林能够改善学习记忆。本文研究一种新的占诺美林衍生物--EUKl001，对老龄小鼠学习记忆能力以及突触可塑性产生的影响。方法：将老龄实验小鼠（CBA，18月）分4组，分别腹腔注射生理盐水，占诺美林（Img／kg），以及EUKl001（0．1mg／kg和lmg／kg），持续注射15天，注射第十五天进行新奇事物识别实验。此外，用离体脑片电生理技术研究EUKl001（0．1和lμM）对海马CA3-CAl突触可塑性的影响。结果：在新奇事物识别实验的1小时检测中，四组小鼠对于新异目标物体探究时间的比例分别是：生理盐水对照组，47．50％；0．1ing／kg EUKl001，63．6％；lmg／kg EUKl001，64．4％；lmg／kg占诺美林，61．6％．在1天的检测中，各组小鼠对新异目标物体探究时间所占的比例分别是：生理盐水对照组，48．3％；0．1mg／kg EUKl001，58．8％；lmg／kg EUKl001，61．9％；lmg／kg占诺美林，65．2％．结论：EUKl001能改善正常老龄化过程中学习记忆能力的衰退。该化合物的这种效应可能是通过增强海马脑区的突触可塑性来实现的。     

一种新的呫诺美林衍生物改善老年小鼠的记忆能力

目的为了分析EUK1001-新的呫诺美林衍生物的功能性质,本实验以老年小鼠为实验材料,研究了该化合物的急性毒量以及对突触可塑性和识别记忆的影响。方法通过口服及腹腔注射途径,对小鼠进行梯度剂量的毒理学实验,测定EUK1001的半致死剂量（median lethal dose,LD50）;采用新奇物体识别任务和离体脑片电生理学技术研究EUK1001对老年小鼠识别记忆和海马突触可塑性的影响。结果EUK1001比呫诺美林呈现出更小的毒副作用。在新奇事物识别实验中,EUK1001能够显著改善老年小鼠在识别记忆任务中的表现。此外,海马脑片灌流1μmol／L的EUK1001,能直接诱导产生长时程突触增强（long-term potentiation）。结论EUK1001能够改善正常老龄化过程中学列记忆能力的衰退。     

Activation of extracellular signal-regulated kinase in the anterior cingulate cortex contributes to the induction of long-term potentiation in rats

Objective

To explore the role of the extracellular signal-regulated kinase (ERK)/cAMP response element binding protein (CREB) pathway in the induction of long-term potentiation (LTP) in the anterior cingulate cortex (ACC) that may be implicated in pain-related negative emotion.

Methods

LTP of field potential was recorded in ACC slice and the expressions of phospho-ERK (pERK) and phospho-CREB (pCREB) were examined using immunohistochemistry method.

Results

LTP could be induced stably in ACC slice by high frequency stimulation (2-train, 100 Hz, 1 s), while APv (an antagonist of NMDA receptor) could block the induction of LTP in the ACC, indicating that LTP in this experiment was NMDA receptor-dependent. Bath application of PD98059 (50 μmol/L), a selective MEK inhibitor, at 30 min before tetanic stimulation could completely block the induction of LTP. Moreover, the protein level of pERK in the ACC was transiently increased after LTP induction, starting at 5 min and returning to basal at 1 h after tetanic stimulation. The protein level of pCREB was also increased after LTP induction. The up-regulation in pERK and pCREB expressions could be blocked by pretreatment of PD98059. Double immunostaining showed that after LTP induction, most pERK was co-localized with pCREB.

Conclusion

NMDA receptor and ERK-CREB pathway are necessary for the induction of LTP in rat ACC and may play important roles in pain emotion.