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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.
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http://dx.doi.org/10.1262/jrd.2025-006 | DOI Listing |
bioRxiv
August 2025
Instituto de Investigaciones Biológicas (IIB-FCEyN/CONICET), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Mar del Plata, Argentina.
Sperm capacitation involves proteolytic remodeling of membrane proteins, including components of the CatSper calcium channel, which is essential for hyperactivation and male fertility. Here, we identify the seminal protease inhibitor SPINK3, a known decapacitation factor that suppresses premature capacitation in the female tract, as the first physiological inhibitor of CATSPER1 processing. In mouse sperm, SPINK3 blocks capacitation-induced CATSPER1 cleavage, preserving a subpopulation with intact CatSper channels and lacking pTyr development in the flagellum.
View Article and Find Full Text PDFMol Reprod Dev
September 2025
Laboratory of Animal Biotechnology, Federal Rural University of Semi-Arid, Mossoró, Brazil.
The increasing focus on understanding spermatozoa mechanisms in rodents aims to enhance reproductive stability and support conservation efforts, particularly for ecologically significant and declining species like the red-rumped agouti. We aimed to evaluate the interaction between capacitation media and time, testing BSA concentrations-low (4 mg/mL) and high (15 mg/mL)-with or without 2 mM calcium chloride (CaCl) across three time points. Epididymal sperm were distributed into five groups: without capacitation agent (WCA), high BSA (HBSA), high BSA with CaCl (HBCa), low BSA (LBSA), and low BSA with CaCl (LBCa), each incubated for 1, 3, or 6 h.
View Article and Find Full Text PDFBiochim Biophys Acta Gene Regul Mech
August 2025
Unidad de Investigación Médica en Immunología e Infectología, Centro Médico Nacional La Raza, Instituto Mexicano del Seguro Social (IMSS), Mexico City 02990, Mexico.. Electronic address:
Catsper3 has been shown to be essential for the proper functioning of CatSper calcium channel, sperm hyperactivation and egg fertilization. Although its function and physiological relevance to male fertility have been characterized, nothing is known about its regulation at the transcriptional level. Here, we identified the murine Catsper3 promoter and evaluated the role of CREBA and CREMτ transcription factors (TF) on its regulation.
View Article and Find Full Text PDFTheriogenology
August 2025
Laboratory of Chromosome Biology, Max Planck Institute of Biochemistry, Martinsried, DE-82152, Germany. Electronic address:
Calcium (Ca) is known as a key regulator of sperm physiology, playing a crucial role in capacitation, hyperactivation, the acrosome reaction, and fertilisation. Despite this, whether it shapes the sperm's ability to withstand liquid preservation has not been addressed. Herein, we investigated how altering Ca availability to pig sperm during storage at 17 °C affects their quality and metabolic activity.
View Article and Find Full Text PDFAndrology
August 2025
Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Hiroshima, Japan.
Background: Energy metabolism and substrate balance are critical determinants of sperm motility and fertility. Linear motility is necessary for sperm forward movement, whereas hyperactivated motility is a prerequisite for fertilization. The preference of metabolic pathways depends on substrate availability which controls sperm motility.
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