Impact of a mild scrotal heat stress on DNA integrity in murine spermatozoa.
An increase in scrotal temperature can lead to the production of poor quality spermatozoa and infertility. In the present study we have used mice to examine the impact of mild, scrotal heat stress (42 degrees C for 30 min) on numbers of spermatozoa as well as on the integrity of their DNA. Spermatozoa recovered from the epididymides hours (1 to 24) or days (7 to 32) after treatment were analysed using COMET and sperm chromatin structure (SCSA) assays. The treatment induced a stress response in both the testis and the epididymis that was associated with reduced expression of the cold inducible RNA binding protein (Cirp) and an increase in germ cell apoptosis (Apotag positive cells). Although spermatozoa present in the epididymis at the time of heating contained correctly packaged DNA, its integrity was compromised by heat stress. In addition, although some germ cells, which were present within the testis at the time of heat stress, were removed by apoptosis, many germ cells completed their development and were recovered as motile spermatozoa with damaged DNA. In conclusion, these data demonstrate that scrotal heat stress can compromise the DNA integrity of spermatozoa and this may have clinical implications for patients undergoing IVF and intra-cytoplasmic sperm injection (ICSI).
Banks
Stephen
S
MRC Human Reproductive Sciences Unit, The Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 4SB, UK.
King
Sasha A
SA
Irvine
D Stewart
DS
Saunders
Philippa T K
PT
D000818:Animals; D017209:Apoptosis; D002843:Chromatin / Q000648:ultrastructure; D020552:Comet Assay; D004249:DNA Damage; D004822:Epididymis; D006358:Hot Temperature / Q000009:adverse effects*; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D051379:Mice; D016601:RNA-Binding Proteins / Q000032:analysis; D012611:Scrotum; D013076:Sperm Count; D013094:Spermatozoa / Q000378:metabolism* / Q000648:ultrastructure; D013737:Testis
D002843:Chromatin; C106176:Cirbp protein, mouse; D016601:RNA-Binding Proteins