Hidaka Soh
Department of Physiology, Fujita Health University, School of Medicine, Toyoake, Aichi 470-1192, Japan.
J Integr Neurosci. 2009 Sep;8(3):299-322. doi: 10.1142/s0219635209002198.
Serotonin [5-hydroxytryptamine (5-HT)] is a common neurotransmitter/neuromodulator found widely in the nervous system. Cellular morphology and retinal distribution of serotonergic amacrine cells in the channel catfish (Ictalurus punctatus) retina are identified using monoclonal anti-5HT antibody. These cells receive ribbon synapses from OFF-center (hyperpolarizing) bipolar cells as well as conventional synapses with other non-serotonergic amacrine cells. Output synapses from the serotonergic cells are mainly channel onto retinal ganglion cells. Output synapses from the serotonergic cells occur as "the branched synapses" onto the ganglion cell dendrites at the dyads of the ribbon synaptic sites, and are made onto the ganglion cells, apart from the ribbon synapses. Application of serotonin receptor agonist: 5HT(1A) serotonin receptor agonist, (+)-8-hydroxy-dipropylaminotetralin [8-OH-DPAT; 1-10 muM] is also known to activate 5HT(7) serotonin receptor, coupled with activation of adenylate cyclase, generated continuous repetitive spikes from large retinal ganglion cells of the adult goldfish (Carassius auratus) in flat-mounted preparations, using amphotericin-B-perforated patch-clamp. Under control conditions of bleached retina with continuous light illumination, goldfish large retinal ganglion cells had generated only few spikes. This is the first observation of positive neuromodulation promoting retinal ganglion cell excitation in the retina. The results confirm previous reports of a serotonergic system in the mammalian retina. These results support the presence of developed postsynaptic serotonin receptors in cyprinid fish retina together with other physiological and anatomical studies, and suggest that the action of serotonin in the retina may be more important than previously believed.
血清素[5-羟色胺(5-HT)]是一种常见的神经递质/神经调质，广泛存在于神经系统中。使用单克隆抗5HT抗体鉴定了斑点叉尾鮰视网膜中血清素能无长突细胞的细胞形态和视网膜分布。这些细胞接受来自离中心(超极化)双极细胞的带状突触以及与其他非血清素能无长突细胞的常规突触。血清素能细胞的输出突触主要传导至视网膜神经节细胞。血清素能细胞的输出突触以“分支突触”的形式出现在带状突触位点的二联体处的神经节细胞树突上，除了带状突触外，还与神经节细胞形成突触。血清素受体激动剂的应用：5HT(1A)血清素受体激动剂，(+)-8-羟基二丙基氨基四氢萘[8-OH-DPAT；1-10μM]也已知可激活5HT(7)血清素受体，与腺苷酸环化酶的激活相结合，使用两性霉素B穿孔膜片钳技术，在成年金鱼(Carassius auratus)的平铺标本中，从大型视网膜神经节细胞产生连续重复的动作电位。在持续光照漂白视网膜的对照条件下，金鱼大型视网膜神经节细胞仅产生少量动作电位。这是首次观察到正向神经调节促进视网膜神经节细胞兴奋。这些结果证实了先前关于哺乳动物视网膜中血清素能系统的报道。这些结果与其他生理和解剖学研究一起支持鲤科鱼类视网膜中存在发达的突触后血清素受体，并表明血清素在视网膜中的作用可能比先前认为的更重要。
