Resumen: Melatonin affects sperm physiology, possibly through membrane receptors. Effects were tested at low concentrations (1 pM, 100 pM, 10 nM and 1 mu M) in red deer epididymal spermatozoa as a model for high-seasonality species. Samples were incubated with melatonin as uncapacitated or capacitating conditions (heparin) and evaluated for motility and physiology (flow cytometry). Most effects occurred at low concentrations (nM-pM), mainly protecting from apoptosis and maintaining acrosomal integrity, suggesting a role for membrane receptors rather than a direct antioxidant effect. Intracellular calcium was not affected, differing from other studies and perhaps because of the epididymal origin. This study supports the relevance of melatonin on sperm physiology and could contribute to the application of reproductive technologies in wild ruminants. Idioma: Inglés DOI: 10.1111/rda.14137 Año: 2022 Publicado en: Reproduction in Domestic Animals 57, 55 (2022), 82-85 ISSN: 0936-6768 Factor impacto JCR: 1.7 (2022) Categ. JCR: VETERINARY SCIENCES rank: 55 / 144 = 0.382 (2022) - Q2 - T2 Categ. JCR: AGRICULTURE, DAIRY & ANIMAL SCIENCE rank: 33 / 62 = 0.532 (2022) - Q3 - T2 Categ. JCR: REPRODUCTIVE BIOLOGY rank: 29 / 31 = 0.935 (2022) - Q4 - T3 Factor impacto CITESCORE: 3.2 - Biochemistry, Genetics and Molecular Biology (Q3) - Agricultural and Biological Sciences (Q2)