Nitric oxide signals that Aplysia have attempted to eat, a necessary component of memory formation after learning that food is inedible
Nitric oxide signals that Aplysia have attempted to eat, a necessary component of memory formation after learning that food is inedible
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DOI：
10.1152/jn.00056.2006
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发表时间：
2006-09-01
影响因子：
2.5
通讯作者：
Susswein, Abraham J.
中科院分区：
文献类型：
--
作者：
Katzoff, Ayelet;Ben-Gedalya, Tziona;Susswein, Abraham J.
在学习过程中抑制一氧化氮（NO）的合成，食物是不可食用的，会阻止随后的记忆形成。为了深入了解NO传输在学习过程中的功能，我们测试了阻断NO合成是否会影响在非学习环境和学习过程中表达的喂养方面。用L-NAME抑制NO合成和用亚甲蓝阻断鸟苷酸环化酶降低了自由采食的功效。D-NAME没有效果。L-NAME也降低排斥反应频率，但不影响排斥幅度。L-NAME的作用通过减少吞咽努力不成功的信号传导来解释，导致排斥率降低，以及在随意进食中重新定位和随后消耗食物的能力降低。动物努力吞咽的信号是学习食物不可食用的关键组成部分。仅用食物刺激嘴唇并不能产生记忆，但刺激与NO供体SNAP结合确实产生了记忆。外源性NO在一定浓度下引起记忆，也会刺激对NO产生反应的关键神经元MCC。在训练过程中，亚甲蓝阻断cGMP第二信使级联反应也阻断了学习后的记忆形成。我们的数据表明，在学习食物不可食用的过程中，记忆来自三个事件的偶然性。其中一个事件是吞咽的努力，这是通过cGMP的NO信号。
Inhibiting nitric oxide (NO) synthesis during learning that food is inedible in Aplysia blocks subsequent memory formation. To gain insight into the function of NO transmission during learning we tested whether blocking NO synthesis affects aspects of feeding that are expressed both in a nonlearning context and during learning. Inhibiting NO synthesis with L-NAME and blocking guanylyl cyclase with methylene blue decreased the efficacy of ad libitum feeding. D-NAME had no effect. L-NAME also decreased rejection responses frequency, but did not affect rejection amplitude. The effect of L-NAME was explained by a decreased signaling that efforts to swallow are not successful, leading to a decreased rejection rate, and a decreased ability to reposition and subsequently consume food in ad libitum feeding. Signaling that animals have made an effort to swallow is a critical component of learning that food is inedible. Stimulation of the lips with food alone did not produce memory, but stimulation combined with the NO donor SNAP did produce memory. Exogenous NO at a concentration causing memory also excited a key neuron responding to NO, the MCC. Block of the cGMP second-messenger cascade during training by methylene blue also blocked memory formation after learning. Our data indicate that memory arises from the contingency of three events during learning that food is inedible. One of the events is efforts to swallow, which are signaled by NO by cGMP.