Sperm preparedness and adaptation to osmotic and pH stressors relate to functional competence of sperm in Bos taurus

Maharajan Lavanya, Santhanahalli Siddalingappa Archana, Divakar Swathi, Laxman Ramya, Arunachalam Arangasamy, Balakrishnan Binsila, Arindam Dhali, Narayanan Krishnaswamy, Sanjay Kumar Singh, Harendra Kumar, Muniandy Sivaram, Sellappan Selvaraju

Reproductive Physiology Laboratory, Animal Physiology Division, ICAR-National Institute of Animal Nutrition and Physiology, Adugodi, Bengaluru 560030, India; Department of Animal Reproduction, Indian Veterinary Research Institute, Izatnagar, Bareilly 243122, India; Omics Laboratory, Bioenergetics and Environmental Sciences Division, ICAR-National Institute of Animal Nutrition and Physiology, Adugodi, Bengaluru 560030, India; Indian Veterinary Research Institute, Bangalore 560024, India; Southern Regional Station, ICAR-National Dairy Research Institute, Adugodi, Bengaluru 560030, India

Abstract: The adaptive ability of sperm in the female reproductive tract micromilieu signifies the successful fertilization process. The study aimed to analyze the preparedness of sperm to the prevailing osmotic and pH stressors in the female reproductive tract. Fresh bovine sperm were incubated in 290 (isosmotic-control), 355 (hyperosmotic-uterus and oviduct), and 420 (hyperosmotic-control) mOsm/kg and each with pH of 6.8 (uterus) and 7.4 (oviduct). During incubation, the changes in sperm functional attributes were studied. Sperm kinematics and head area decreased significantly (p < 0.05) immediately upon exposure to hyperosmotic stress at both pH. Proportion of sperm capacitated (%) in 355 mOsm/kg at 1 and 2 h of incubation were significantly (p < 0.05) higher than those in 290 mOsm media. The magnitude and duration of recovery of sperm progressive motility in 355 mOsm with pH 7.4 was correlated with the ejaculate rejection rate (R2 = 0.7). Using this information, the bulls were divided into good (n = 5) and poor (n = 5) osmo-adapters. The osmo-responsive genes such as NFAT5, HSP90AB1, SLC9C1, ADAM1B and GAPDH were upregulated (p < 0.05) in the sperm of good osmo-adapters. The study suggests that sperm are prepared for the osmotic and pH challenges in the female reproductive tract and the osmoadaptive ability is associated with ejaculate quality in bulls.

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Nature, Scientific Reports (2021) 11:22563 – https://doi.org/10.1038/s41598-021-01928-6
Published: 19 November 2021