Matsuo Ryota, Kobayashi Suguru, Wakiya Kyoko, Yamagishi Miki, Fukuoka Masayuki, Ito Etsuro
International College of Arts and Sciences, Fukuoka Women's University, Fukuoka, 813-8529, Japan; Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Kagawa, 769-2193, Japan.
J Comp Neurol. 2014 Sep 1;522(13):2951-66. doi: 10.1002/cne.23559. Epub 2014 Apr 3.
Acetylcholine plays various important roles in the central nervous system of invertebrates as well as vertebrates. In the olfactory center of the terrestrial slug Limax, the local field potential (LFP) oscillates, and the change in its oscillatory frequency is thought to correlate with the detection of odor that potentially changes an ongoing behavior of the animal. Acetylcholine is known to upregulate the frequency of the LFP oscillation, and is one of the candidates for the neurotransmitters that are involved in such higher cognitive functions. However, there have been no histological data on the cholinergic system in gastropods, nor are there data on the receptors that are responsible for the upregulation of the oscillatory frequency of LFP due to the lack of analytical tools (such as antibodies or cDNA sequence information on cholinergic system-related genes). Here we cloned the cDNAs of choline acetyltransferase (ChAT), acetylcholinesterase, vesicular acetylcholine transporter, and several nicotinic acetylcholine receptors (nAChRs), and investigated their localization in the brain of Limax. We also generated a polyclonal antibody against ChAT to examine its localization, and investigated pharmacologically the involvement of nAChRs in the LFP oscillation. Our data showed: 1) dense distribution of the neurons expressing mRNAs of ChAT and vesicular acetylcholine transporter in the olfactory center; 2) spatially unique expression patterns of different nAChRs in the olfactory center; 3) involvement of nAChRs in the upregulation of the oscillation; 4) localization of ChAT protein in nerve fibers and/or terminals; and 5) the presence of cholinergic nerves in the tentacles.
乙酰胆碱在无脊椎动物和脊椎动物的中枢神经系统中发挥着多种重要作用。在陆生蛞蝓Limax的嗅觉中枢，局部场电位（LFP）会振荡，其振荡频率的变化被认为与气味检测相关，而气味可能会改变动物正在进行的行为。已知乙酰胆碱会上调LFP振荡的频率，并且是参与此类高级认知功能的神经递质候选物之一。然而，目前尚无关于腹足纲动物胆碱能系统的组织学数据，也没有关于因缺乏分析工具（如胆碱能系统相关基因的抗体或cDNA序列信息）而导致LFP振荡频率上调的受体的数据。在这里，我们克隆了胆碱乙酰转移酶（ChAT）、乙酰胆碱酯酶、囊泡乙酰胆碱转运体以及几种烟碱型乙酰胆碱受体（nAChRs）的cDNA，并研究了它们在Limax大脑中的定位。我们还制备了针对ChAT的多克隆抗体以检查其定位，并从药理学角度研究了nAChRs在LFP振荡中的作用。我们的数据显示：1）在嗅觉中枢中，表达ChAT和囊泡乙酰胆碱转运体mRNA的神经元分布密集；2）不同nAChRs在嗅觉中枢具有空间独特的表达模式；3）nAChRs参与振荡的上调；4）ChAT蛋白定位于神经纤维和/或终末；5）触角中存在胆碱能神经。
