Pedreira M E, Dimant B, Tomsic D, Quesada-Allue L A, Maldonado H
Facultad de Ciencias Exactas y Naturales, Depto Biología, Buenos Aires University, Argentina.
Pharmacol Biochem Behav. 1995 Oct;52(2):385-95. doi: 10.1016/0091-3057(95)00124-f.
A shadow moving over head elicits an escape response in the crab Chasmagnathus that habituates promptly and for a long period. The effect of the protein synthesis inhibitor cycloheximide (CY) on this long-term memory was analyzed. Two hours after injection, 10 micrograms CY inhibited [14C]-amino amino acid incorporation into cerebral plus thoracic ganglia by 88% and 20 micrograms by 92%, but no inhibition was found at 24 h. A single injection of 10-20 micrograms CY given 30 min before training, failed to affect the short-term habituation. Similar doses impaired both context memory (CM) and long-term habituation (LTH) when tested at 72 and 120 h but only CM at 24 h. Such a disparity was explained by an unspecific depressing effect upon the response, attributed to an interaction between CY and training. The hypothesis was confirmed, because CY injected immediately after training disclosed amnestic effect at 24 h on both CM and LTH. A similar effect was proven when animals were injected at 2 h but not at 6 h after training. Results from experiments with pretraining and pretesting injections put aside a state-dependence or retrieval deficit effects of the drug. Taken together, findings of this article argue strongly for de novo protein synthesis as a mechanism of LTH and for the close relation between CM and LTH.
头顶上方移动的阴影会引发招潮蟹的逃避反应，这种反应会迅速且长期地产生习惯化。分析了蛋白质合成抑制剂环己酰亚胺（CY）对这种长期记忆的影响。注射后两小时，10微克CY可使[14C]-氨基酸掺入脑加胸神经节的量减少88%，20微克可减少92%，但在24小时时未发现抑制作用。在训练前30分钟单次注射10 - 20微克CY，并未影响短期习惯化。当在72小时和120小时进行测试时，相似剂量会损害情境记忆（CM）和长期习惯化（LTH），但在24小时时仅损害CM。这种差异被解释为CY与训练之间的相互作用对反应产生的非特异性抑制作用。这一假设得到了证实，因为训练后立即注射CY在24小时时对CM和LTH均显示出遗忘效应。当动物在训练后2小时而非6小时注射时，也证实了类似的效果。预训练和预测试注射实验的结果排除了药物的状态依赖性或检索缺陷效应。综上所述，本文的研究结果有力地支持了从头合成蛋白质作为长期习惯化的一种机制，以及情境记忆和长期习惯化之间的密切关系。
