Suzuki Issei, Fujinoki Masakatsu, Kamai Takao
Department of Urology, Dokkyo Medical University, Tochigi 321-0293, Japan.
Research Lab of Laboratory Animals, Research Center for Laboratory Animals, Comprehensive Research Facilities for Advanced Medical Science, School of Medicine, Dokkyo Medical University, Tochigi 321-0293, Japan.
J Reprod Dev. 2025 Oct 9;71(5):256-265. doi: 10.1262/jrd.2025-006. Epub 2025 Aug 3.
L-tryptophan (Trp), an essential amino acid, is a precursor of 5-hydroxytryptamine (5-HT; also known as serotonin) that promotes mammalian sperm hyperactivation. Since mammalian sperm contain Trp hydroxylase (TPH), they may contribute to 5‑HT biosynthesis. Therefore, this study aimed to examine the effect of Trp on hamster sperm hyperactivation and determine whether sperm are involved in 5-HT biosynthesis. Trp significantly enhanced sperm hyperactivation via the 5-HT receptor and its associated signals. In contrast, D-tryptophan did not affect sperm hyperactivation. Furthermore, hamster sperm contained the 5-HT biosynthesis enzymes TPH and aromatic L-amino acid decarboxylase (AADC). Additionally, hamster sperm secreted 5-HT. Trp-enhanced hyperactivation and 5-HT secretion were significantly inhibited by TPH and AADC inhibitors. Overall, our findings suggest that Trp enhanced sperm hyperactivation through the biosynthesis of 5-HT within the sperm.
L-色氨酸（Trp）是一种必需氨基酸，是促进哺乳动物精子超活化的5-羟色胺（5-HT；也称为血清素）的前体。由于哺乳动物精子含有色氨酸羟化酶（TPH），它们可能参与5-HT的生物合成。因此，本研究旨在研究Trp对仓鼠精子超活化的影响，并确定精子是否参与5-HT的生物合成。Trp通过5-HT受体及其相关信号显著增强精子超活化。相比之下，D-色氨酸不影响精子超活化。此外，仓鼠精子含有5-HT生物合成酶TPH和芳香族L-氨基酸脱羧酶（AADC）。另外，仓鼠精子分泌5-HT。TPH和AADC抑制剂显著抑制了Trp增强的超活化和5-HT分泌。总体而言，我们的研究结果表明，Trp通过精子内5-HT的生物合成增强了精子超活化。
