Diminished decondensation and DNA synthesis in activated sperm from rats treated with cyclophosphamide

Standard andrology tests do not predict fertility or assess the genetic qua lity of spermatozoa. To address these problems, we have analyzed sperm nucl ear activation in vitro using cytoplasmic extracts of Xenopus laevis frog e ggs. The objective of this study was to determine if rat sperm chemically d amaged 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 wer e isolated, and incubated in cytoplasmic extracts of X. laevis frog eggs to induce chromatin decondensation and DNA synthesis in vitro. Sperm from tre ated rats displayed significant decreases in both decondensation and DNA sy nthesis when compared to sperm from control rats, consistent with the prese nce of CP-induced DNA crosslinks. No differences in body, testes, or epidid ymal 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 detri mental effects on sperm count, and testis and epididymal weights. (C) 2000 Published by Elsevier Science Ireland Ltd. All rights reserved.