Giocomo Lisa M, Hasselmo Michael E
Department of Psychology, Center for Memory and Brain, 2 Cummington Street, Boston University, Boston, MA, 02215, USA.
Eur J Neurosci. 2005 Sep;22(6):1349-56. doi: 10.1111/j.1460-9568.2005.04316.x.
Cholinergic modulation of synaptic transmission in the hippocampus appears to be involved in learning, memory and attentional processes. In brain slice preparations of hippocampal region CA3, we have explored the effect of nicotine on the afferent connections of stratum lacunosum moleculare (SLM) vs. the intrinsic connections of stratum radiatum (SR). Nicotine application had a lamina-selective effect, causing changes in synaptic transmission only in SLM. The nicotinic effect in SLM was characterized by a transient decrease in synaptic potential size followed by a longer period of enhancement of synaptic transmission. The effect was blocked by gamma-aminobutyric acid (GABA)ergic antagonists, indicating the role of GABAergic interneurons in the observed nicotinic effect. The biphasic nature of the nicotinic effect could be due to a difference in receptor subtypes, as supported by the effects of the nicotinic antagonists mecamylamine and methyllycaconitine. Nicotinic modulation of glutamatergic synaptic transmission could complement muscarinic suppression of intrinsic connections, amplifying incoming information and providing a physiological mechanism for the memory-enhancing effect of nicotine.
海马体中突触传递的胆碱能调节似乎与学习、记忆和注意力过程有关。在海马体CA3区的脑片制备中，我们探究了尼古丁对分子层（SLM）传入连接与辐射层（SR）内在连接的影响。应用尼古丁具有层选择性效应，仅在SLM中引起突触传递的变化。SLM中的烟碱效应表现为突触电位大小短暂降低，随后是突触传递增强的较长时期。该效应被γ-氨基丁酸（GABA）能拮抗剂阻断，表明GABA能中间神经元在观察到的烟碱效应中起作用。烟碱效应的双相性质可能是由于受体亚型的差异，烟碱拮抗剂美加明和甲基lycaconitine的作用支持了这一点。谷氨酸能突触传递的烟碱调节可以补充毒蕈碱对内在连接的抑制作用，放大传入信息，并为尼古丁的记忆增强作用提供一种生理机制。
