title: Cadmium accumulation and binding characteristics in intact Sertoli/germ cell units, and associated effects on stage-specific functions in vitro: insights from a shark testis model.
abstract: The increased human use of cadmium (Cd) and its increased occurrence in the environment is of concern. The testis is sensitive to Cd because of the steroid-mediated regulation of spermatogenesis, high levels of DNA synthesis and gene transcription, all of which varies in a stage-related manner. Validated techniques (acridine orange vital staining to detect apoptosis and dextran-rhodamine exclusion to assess blood-testis barrier function) were recently developed and the shark testis was proposed as an alternative model for assessing stage-specific functions in living testicular tissue and to study toxicant actions on spermatogenesis. The present paper shows that 109Cd accumulation and binding in vitro was stage-dependent (premeiotic, PrM > meiotic, M > postmeiotic, PoM), rapid and persisted in spermatocysts (intact germ cell/Sertoli cell units) 49 h after washout. In competitive binding analyses of all three spermatocyst stages, Hg, but not Zn, could replace bound 109Cd, suggesting that Cd binding was specific. These findings were associated with a biphasic apoptotic response in the PrM spermatocysts, which was maximal at 10 microm CdCl2 and 1 microm CdCl2 after 2 and 4 days in culture, respectively. Although Cd uptake in PoM cysts was more than 2-fold less than uptake in PrM cysts, the percentage dextran-rhodamine permeant PoM cysts was approximately 8-fold greater than in controls in the presence of both 10 microm CdCl2 and 30 microm CdCl2 after 4 days culture, indicating that blood-testis barrier function in PoM spermatocysts was compromised. These findings demonstrate that this model has utility for use in screening assays of environmental toxicants.
authors.affiliation: Department of Physiology, Faculty of Health Sciences, University of Pretoria, P.O. Box 2034, Pretoria, South Africa. leonmcclusky@yahoo.com
authors.forename: Leon M
authors.initials: LM
authors.lastname: McClusky
mesh_terms: D000818:Animals; D017209:Apoptosis; D001667:Binding, Competitive; D001814:Blood-Testis Barrier / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D019256:Cadmium Chloride / Q000378:metabolism* / Q000633:toxicity; D002106:Cadmium Radioisotopes; D002470:Cell Survival; D004261:DNA Replication; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000378:metabolism* / Q000633:toxicity; D008297:Male; D008856:Microscopy, Fluorescence; D023421:Models, Animal; D018570:Risk Assessment; D012708:Sertoli Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D013091:Spermatogenesis; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D048251:Squalus acanthias / Q000378:metabolism*; D013737:Testis / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D013997:Time Factors; D046509:Tissue Culture Techniques; D014018:Tissue Distribution; D018675:Toxicity Tests / Q000379:methods*
chemical_list: D002106:Cadmium Radioisotopes; D004785:Environmental Pollutants; D019256:Cadmium Chloride