Washington B, Higgins D E, McAdory B, Newkirk R F
Biomedical Research Center, Xavier University of Louisiana, New Orleans 70125.
J Comp Neurol. 1994 Sep 8;347(2):312-20. doi: 10.1002/cne.903470212.
It has been suggested that serotonin serves as a neurotransmitter in the horseshoe crab, Limulus polyphemus. While some studies of identified groups of central neurons have been conducted, little is known concerning the neuronal organization in Limulus central ganglia. This study was undertaken to determine the localization of serotoninergic neurons in the opisthosomal ventral nerve cord of Limulus and to construct a basis for further comparative biochemical and pharmacological studies of the specific function of these neurons. Endogenous serotonin was detected in the ventral nerve cord (chain of abdominal ganglia) by high-performance liquid chromatography and electrochemical detection (HPLC-EC). Endogenous serotonin was quantified in the 9th through 13th ganglia, anterior (hemal) nerves, posterior (branchial) nerves, and connectives. The serotonin content in the abdominal ganglia was significantly reduced when the ganglia were incubated for 24 hours in Leibovitz's (L-15) medium containing reserpine or 5,7-dihydroxytryptamine (5,7-DHT), neurotoxins that block the uptake of serotonin into storage vesicles. The distribution of serotonin-immunoreactive neurons in the ventral nerve cord was determined by indirect immunocytochemistry. Treatment of the chain of ganglia with an anti-serotonin antiserum followed by treatment with a fluorescent-labeled antiserum raised against the primary antibody demonstrated specific staining in each ganglion, the ganglionic roots, and connectives. Clusters of serotonin-immunoreactive neurons were observed anteriolaterally and posteriorly in each ganglion. Processes from dense fiber bundles extended from these clusters of neurons to the central region of each ganglion. These results demonstrate that serotonin-immunoreactive neurons are present in the opisthosomal ventral nerve cord of the horseshoe crab and that serotonin may function as a neurotransmitter.
有人提出，血清素在鲎（美洲鲎）中作为一种神经递质发挥作用。虽然已经对特定的中枢神经元群体进行了一些研究，但对于鲎中枢神经节中的神经元组织了解甚少。本研究旨在确定血清素能神经元在鲎体后端腹神经索中的定位，并为进一步比较这些神经元特定功能的生化和药理学研究奠定基础。通过高效液相色谱和电化学检测（HPLC-EC）在腹神经索（腹神经节链）中检测到内源性血清素。对第9至13神经节、前（血）神经、后（鳃）神经和神经索中的内源性血清素进行了定量分析。当神经节在含有利血平或5,7-二羟基色胺（5,7-DHT）的莱博维茨（L-15）培养基中孵育24小时时，腹神经节中的血清素含量显著降低，利血平和5,7-DHT是阻止血清素摄取到储存囊泡中的神经毒素。通过间接免疫细胞化学确定腹神经索中血清素免疫反应性神经元的分布。用抗血清素抗血清处理神经节链，然后用针对一抗的荧光标记抗血清处理，结果显示每个神经节、神经节根和神经索中均有特异性染色。在每个神经节的前外侧和后侧观察到血清素免疫反应性神经元簇。密集纤维束的突起从这些神经元簇延伸到每个神经节的中心区域。这些结果表明，血清素免疫反应性神经元存在于鲎体后端腹神经索中，并且血清素可能作为一种神经递质发挥作用。
