The Mitochondria of Stallion Spermatozoa Are More Sensitive Than the Plasmalemma to Osmotic‐Induced Stress: Role of c‐Jun N‐terminal Kinase (JNK) Pathway

• Published in: Journal of andrology Vol. 33; no. 1; pp. 105 - 113
• Main Authors: García, Beatriz Macías, Moran, Alvaro Miró, Fernández, Lauro González, Ferrusola, Cristina Ortega, Rodriguez, Antolin Morillo, Bolaños, Juan Maria Gallardo, Silva, Carolina Maria Balao, Martínez, Heriberto Rodríguez, Tapia, Jose A., Peña, Fernando J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.01.2012; American Society of Andrology
• Subjects: Animals; Biological and medical sciences; Flow Cytometry; Fundamental and applied biological sciences. Psychology; Gynecology. Andrology. Obstetrics; Horses; JNK Mitogen-Activated Protein Kinases - antagonists & inhibitors; JNK Mitogen-Activated Protein Kinases - metabolism; JNK/SAPK; Male; Male genital diseases; Mammalian male genital system; Medical sciences; Membrane Potentials; Osmosis; osmotic stress; Sperm; Spermatozoa - ultrastructure; Stress, Physiological; Vertebrates: reproduction; Flow cytometry; Spermatozoa; JNK/SAPK; Enzyme; Sperm; Transferases; Mitogen-activated protein kinase; Germinal cell; Male genital system; Stress; osmotic stress; Mitochondria; Reproduction
• DOI: 10.2164/jandrol.110.011957
• ISSN: 0196-3635; 1939-4640

Cryopreservation introduces extreme temperature and osmolality changes that impart lethal and sublethal effects on spermatozoa. Additionally, there is evidence that the osmotic stress induced by cryopreservation causes oxidative stress to spermatozoa. The main sources of reactive oxygen species in mammalian sperm are the mitochondria. In view of this, the aim of our study was to test whether or not osmotic stress was able to induce mitochondrial damage and to explore the osmotic tolerance of the mitochondria of stallion spermatozoa. Ejaculates from 7 stallions were subjected to osmolalities ranging from 75 to 1500 mOsm/kg, and the effect on sperm membrane integrity and mitochondrial membrane potential was studied. Additionally, the effects of changes in osmolality from hyposmotic to isosmotic and from hyperosmotic to isosmotic solutions were studied (osmotic excursions). The cellular volume of stallion spermatozoa under isosmotic conditions was 20.4 ± 0.33 μm3. When exposed to low osmolality, the stallion spermatozoa behaved like a linear osmometer, whereas exposure to high osmolalities up to 900 mOsm/kg resulted in decreased sperm volume. Although sperm membranes were relatively resistant to changes in osmolality, mitochondrial membrane potential decreased when osmolalities were low or very high (10.7 ± 1.74 and 16.5 ± 1.70 at 75 and 150 mOsm/kg, respectively, and 13.1 ± 1.83 at 1500 mOsm/kg), whereas in isosmolar controls the percentage of stallion sperm mitochondria with a high membrane potential was 41.1 ± 1.69 (P < .01). Osmotic excursions induced greater damage than exposure of spermatozoa to a given nonphysiologic osmolality, and again the mitochondria were more prone to damage induced by osmotic excursions than was the sperm plasma membrane. In search of intracellular components that could mediate these changes, we have detected for the first time the c‐Jun N‐terminal kinase 1/2 in stallion spermatozoa, which are apparently involved in the regulation of the viability of these cells.