Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
Water Security Agency, Saskatoon, SK S7N 3R3, Canada.
J Exp Biol. 2021 May 1;224(9). doi: 10.1242/jeb.242293. Epub 2021 May 4.
A heat stressor (1 h at 30°C) in Lymnaea stagnalis before operant conditioning training of aerial respiration is sufficient to enhance long-term memory (LTM) formation in 'average' cognitive ability, laboratory-reared, inbred snails. However, in freshly collected outbred snails, the same heat stressor blocks LTM formation in 'smart' cognitive phenotype but not in average cognitive phenotype strains. Here, we hypothesize that (1) preventing the stress associated with the heat stressor before training allows LTM to form in the smart phenotype strains; and (2) alleviating the stress before a memory recall session allows a formed LTM to be recalled in the smart phenotype strains. We found that an injection of propranolol, which mitigates the stressor, before snails experience the heat stressor enabled two strains of the smart phenotype snails to form LTM, consistent with our first hypothesis. However, the injection of propranolol before a memory test session did not alleviate a memory recall block in the smart phenotype snails. Thus, our second hypothesis was not supported. Therefore, smart cognitive phenotype snails encountering a heat stressor have an inability to form LTM, but this inability can be overcome by the pre-injection of propranolol.
在进行空中呼吸操作性条件反射训练之前，用热应激源（30°C 下 1 小时）处理圆田螺，足以增强“普通”认知能力、实验室饲养、近交田螺的长期记忆（LTM）形成。然而，在新收集的远交田螺中，相同的热应激源会阻止“聪明”认知表型的 LTM 形成，但不会阻止平均认知表型菌株的 LTM 形成。在这里，我们假设：（1）在训练前防止与热应激源相关的应激可以使 LTM 在“聪明”表型菌株中形成；（2）在记忆回忆期间减轻应激可以使“聪明”表型菌株中的形成 LTM 被回忆起来。我们发现，在蜗牛经历热应激源之前注射普萘洛尔（一种减轻应激源的药物），使两种“聪明”表型蜗牛菌株能够形成 LTM，这与我们的第一个假设一致。然而，在记忆测试前注射普萘洛尔并不能减轻“聪明”表型蜗牛的记忆回忆障碍。因此，我们的第二个假设没有得到支持。因此，遇到热应激源的“聪明”认知表型蜗牛无法形成 LTM，但可以通过预先注射普萘洛尔来克服这种能力不足。
