Similar to hair cells in the mammalian cochlear system, mechanosensory neurons in the Central American wandering spider Cupiennius salei are strongly innervated by efferent fibers that originate from neurons whose somata are located in the central nervous system (CNS). In both the mammalian and arachnid systems, efferent fibers have been shown to co-express two or more transmitters; however, our understanding regarding co-transmission and how it affects sensory signal transduction and processing in these systems is only fragmentary. The spider model system is exceptionally suitable for this type of investigation due to the large size and easy accessibility of the sensory and efferent neurons in this system. Thus far, GABA and glutamate have been identified as the main fast-acting transmitters in efferent axons that form synaptic contacts onto sensory neurons in slit sense organs. Ultrastructural investigations suggest an abundance of neuropeptides within these peripheral synapses. In an effort to identify these peptides and conduct functional studies, we have employed immunohistochemistry to investigate whether the neuropeptide proctolin is present in neurons of the leg ganglia and in peripheral leg structures. Here, we demonstrate that ~ 73% of all neurons in the CNS of C. salei show proctolin-like immunoreactivity (proc-LIR) including the leg ganglia. We demonstrate that both strongly and weakly labeled neurons can be distinguished. The majority of proc-LIR neurons show weak labeling intensity and ~ 86.2% co-localize with glutamate. In future experiments, we plan to undertake functional studies to investigate the significance of this co-expression, which has yet to be investigated.

中文翻译：

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神经肽 proctolin 和谷氨酸在中枢神经系统中的共表达，沿着 Cupiennius salei 的机械感觉神经元和腿部肌肉

与哺乳动物耳蜗系统中的毛细胞类似，中美洲流浪蜘蛛 Cupiennius salei 的机械感觉神经元受传出纤维的强烈支配，传出纤维源自其胞体位于中枢神经系统 (CNS) 的神经元。在哺乳动物和蛛形纲动物系统中，传出纤维已被证明可以共同表达两个或多个发射器。然而，我们对共同传输及其如何影响这些系统中的感觉信号转导和处理的理解只是零碎的。蜘蛛模型系统非常适合这种类型的调查，因为该系统中的感觉和传出神经元尺寸大且易于访问。迄今，GABA 和谷氨酸已被确定为传出轴突中的主要快速作用传递器，它们与狭缝感觉器官中的感觉神经元形成突触接触。超微结构研究表明，这些外周突触内含有丰富的神经肽。为了鉴定这些肽并进行功能研究，我们采用免疫组织化学来研究神经肽 proctolin 是否存在于腿部神经节的神经元和腿部外围结构中。在这里，我们证明了 C. salei 的 CNS 中约 73% 的神经元显示出类凝集素样免疫反应性 (proc-LIR)，包括腿部神经节。我们证明可以区分强标记和弱标记的神经元。大多数 proc-LIR 神经元的标记强度较弱，约 86.2% 与谷氨酸共定位。在以后的实验中，