Although acid-sensing ion channels (ASICs) are widely expressed in the central nervous system, their distribution and roles in axonal growth cones remain unclear. In this study, we examined ASIC localization and function in the axonal growth cones of cultured immature hippocampal neurons. Our immunocytochemical data showed that native and overexpressed ASIC1a and ASIC2a are both localized in growth cones of cultured young hippocampal neurons. Calcium imaging and electrophysiological assay results were utilized to validate their function. The calcium imaging test results indicated that the ASICs (primarily ASIC1a) present in growth cones mediate calcium influx despite the addition of voltage-gated Ca²⁺ channels antagonists and the depletion of intracellular calcium stores. The electrophysiological tests results suggested that a rapid decrease in extracellular pH at the growth cones of voltage-clamped neurons elicits inward currents that were blocked by bath application of the ASIC antagonist amiloride, showing that the ASICs expressed at growth cones are functional. The subsequent immuno-colocalization test results demonstrated that ASIC1a and ASIC2a are both colocalized with Neurofilament-H and Bassoon in mature hippocampal neurons. This finding demonstrated that after reaching maturity, ASIC1a and ASIC2a are both distributed in axons and the presynaptic membrane. Our data reveal the distribution of functional ASICs in growth cones of immature hippocampal neurons and the presence of ASICs in the axons and presynaptic membrane of mature hippocampal neurons, indicating a possible role for ASICs in axonal guidance, synapse formation and neurotransmitter release.

尽管酸敏感离子通道（ASICs）在中枢神经系统中广泛表达，但它们在轴突生长锥中的分布和作用仍不清楚。在这项研究中，我们检查了培养的未成熟海马神经元轴突生长锥中的ASIC定位和功能。我们的免疫细胞化学数据显示，天然的和过表达的ASIC1a和ASIC2a都位于培养的年轻海马神经元的生长锥中。钙成像和电生理测定结果被用来验证其功能。钙成像测试结果表明，尽管添加了电压门控的Ca ²⁺，生长锥中存在的ASIC（主要是ASIC1a）也介导了钙的流入。通道拮抗剂和细胞内钙库的耗竭。电生理测试结果表明，电压钳制的神经元的生长锥处细胞外pH的快速降低会引发内向电流，该内向电流被ASIC拮抗剂阿米洛利的浸浴所阻止，这表明在生长锥处表达的ASIC是有功能的。随后的免疫共定位测试结果表明，在成熟的海马神经元中，ASIC1a和ASIC2a都与Neurofilament-H和Bassoon共定位。这一发现表明，成熟后，ASIC1a和ASIC2a都分布在轴突和突触前膜中。