Diminished decondensation and DNA synthesis in activated sperm from rats treated with cyclophosphamide.
Standard andrology tests do not predict fertility or assess the genetic quality of spermatozoa. To address these problems, we have analyzed sperm nuclear activation in vitro using cytoplasmic extracts of Xenopus laevis frog eggs. The objective of this study was to determine if rat sperm chemically damaged in vivo by cyclophosphamide treatment would respond abnormally in an in vitro rat sperm activation assay (RSAA). Male Sprague-Dawley rats were treated for 6 weeks with cyclophosphamide (CP) to induce DNA damage in post-meiotic germ cells. After the treatment period, cauda epididymal sperm were isolated, and incubated in cytoplasmic extracts of X. laevis frog eggs to induce chromatin decondensation and DNA synthesis in vitro. Sperm from treated rats displayed significant decreases in both decondensation and DNA synthesis when compared to sperm from control rats, consistent with the presence of CP-induced DNA crosslinks. No differences in body, testes, or epididymal weights were observed between control and treated rats, nor was sperm count diminished in the treatment group. These results demonstrate that the RSAA can be used to detect damaged sperm chromatin in the absence of detrimental effects on sperm count, and testis and epididymal weights.
Sawyer
D E
DE
Department of Human Biological Chemistry and Genetics, The University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-0645, USA.
Brown
D B
DB
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000648:ultrastructure; D002843:Chromatin / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D003520:Cyclophosphamide / Q000633:toxicity*; D003600:Cytosol / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis*; D004249:DNA Damage; D005260:Female; D007091:Image Processing, Computer-Assisted; D008297:Male; D010063:Ovum / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D013084:Sperm-Ovum Interactions / Q000187:drug effects; D013094:Spermatozoa / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D014982:Xenopus laevis
D002843:Chromatin; D003520:Cyclophosphamide; D004247:DNA