Neuroethological analysis of memory retention in conditioned taste aversion.

静脉麻醉剂如异丙酚已知会引起遗忘和逆行性遗忘。在以前的工作中，这些麻醉剂已被报道不影响收购的条件性味觉厌恶（CTA）的应用之前的条件性刺激（CS）的介绍。另一方面，去甲肾上腺素能系统被认为对记忆保持起重要作用。因此，我们研究了在CS和非条件刺激（US）之间应用丙泊酚对CTA保持的影响。在所有检查的浓度下，丙泊酚均不影响CTA的采集。然而，CTA的保留被它们剂量依赖性地抑制。α 2受体阻滞剂育亨宾也显著损害CTA的保留。这些结果表明，低浓度的丙泊酚影响CTA记忆保持机制，包括α 2去甲肾上腺素能受体。本研究以C57 BL/6小鼠为实验对象，采用即时早期基因cFos免疫反应性（Fos-IR）作为神经元激活的标记蛋白，对异丙酚在脑内的感受性部位进行了研究。在CTA采集后1h，采用经心α α灌注法固定小鼠脑，比较异丙酚组（异丙酚组）和生理盐水对照组在次级味觉中枢、臂旁核（PBN）、丘脑前核、杏仁核和大脑皮质味觉区（岛皮质）的Fos-IR。我们发现，Fos-IR倾向于增加基底外侧杏仁核，尽管没有显着差异，在所有的大脑区域检查。这些结果表明，杏仁核在CTAM的保持和获得中起着重要的作用。

Intravenous anesthetics such as propofol are known to induce antero- and retrograde amnesia. In previous works, these anesthetics have been reported not to affect the acquisition of conditioned taste aversion(CTA) by their application prior to the presentation of conditioned stimulus(CS). On the other hand, the noradrenergic system is thought to play an important role for the memory retention. Therefore, we examined the effect of propofol applied between CS and unconditioned stimulus(US) on retention of CTA. Propofol did not affect the acquisition of CTA in all concentrations examined. However, the retention of CTA was dose-dependently suppressed by them. An alpha2 blocker, yohimbine, also remarkably impaired the retention of CTA. These results suggest that low concentrations of propofol affect the CTA memory retention mechanism including alpha2 noradrenergic receptors. The similar results were obtained with mice from a mouse inbred strain, C57BL/6,suggesting that mice have a common site sensitive to propofol in the emotional learning and memory system to rats.We tried to identify the receptive site of propofol in the brain, using an immediately early gene, cFos immunoreactivity (Fos-IR) as a maker protein for neuronal activation. The mice brain was fixed by transcardial α α perfusion 1 hr after CTA acquisition and Fos-IR of a group injected with propofol (propofol group) was compared to that of a control group injected with physiological saline at several brain area including the secondary center of gustatory sense, parabrachial nucleus(PBN), the anterior nuclei of thalamus, the amygdala and the cerebral cortex gustatory area (insular cortex). We found that Fos-IR tend to increase in the basolateral amygdala, in spite of no significant difference in all the brain area examined. These results suggest that the amygdala plays important roles on the retention as well as the acquisition of CTAM.