HTR1A and hereditary elliptocytosis: In the present study, we investigated the mechanism of its analgesic effect using the hot-plate test and the writhing assay, by i.c.v. injections of 5-HT1A receptor, 5-HT2A receptor agonists, and antagonists, with the aim to reveal the relationship of analgesic effect between HE and the 5-HT receptors.