Ambient Heat Induces Alteration Of Mouse Epididymal Sperm Chromatin Structure.
D. Evenson*, B. Sailer, L. Jost and L. Sarkar, Olson Biochemistry Laboratories, South Dakota State University, Brookings, SD.
The objective of this study was to determine the effects of increased scrotal temperatures on mouse testicular germ cells and chromatin structure of epididymal sperm. The scrotal region was exposed to water bath temperatures of 38.0°, 40.0° and 42.0°C for 60 min. The mice were killed 1, 3, 7, 11, 14, 21 and 35 days later. Flow cytometry measurements were made on acridine orange stained fresh testicular cells and frozen/thawed epididymal sperm. Mice exposed to 38.0°C showed no significant changes in testicular or sperm data relative to control mice, while mice exposed to 42.0°C demonstrated major damage to testicular and sperm cells at all time points. Testicular cell population ratios for mice exposed to 40.0°C varied (p<.001) from controls 11 and 14 days after exposure. Epididymal sperm from mice exposed to 40.0°C demonstrated a significant increase (p<.01 to p<0.001) in susceptibility to DNA denaturation in situ from days 3 to 14 post exposure. Thus, sperm chromatin structure is susceptible to heat induced damage in the final stages of differentiation.
Supported by EPA #CR820968, NSF #QSR-9108773 and South Dakota Futures Fund.