title: Exogenous stem cell factor (SCF) compensates for altered endogenous SCF expression in 2,5-hexanedione-induced testicular atrophy in rats.
abstract: 2,5-Hexanedione (2,5-HD) is a Sertoli cell toxicant that causes irreversible testicular atrophy in rats. After toxicant exposure, only Sertoli cells, stem cells, and a few committed type A spermatogonia remain in the seminiferous epithelium. A majority of the stem cell progeny differentiate into type A spermatogonia, but then, rather than continuing to differentiate, undergo apoptosis. We hypothesized that the cause for germ cell apoptosis was, at least in part, a deficiency in the function of stem cell factor (SCF), a paracrine growth factor normally made by Sertoli cells. To test this hypothesis, rats were exposed to 1% 2,5-HD for 5 wk and killed at various times after toxicant exposure. Northern blot analysis and reverse transcription-polymerase chain reaction (RT-PCR) were used to determine that, unlike what was observed in control testes, the majority of SCF was expressed in the soluble form after 2,5-HD injury. In vitro co-culture experiments were used to establish the appropriate dose of SCF to administer in vivo. A continuous intratesticular delivery system was established and used to expose 2,5-HD-treated rats to SCF for 2 wk. Animals were exposed to bromodeoxycytidine (BrdCyd) for 2 days before being killed in order to assess the effect of SCF on germ cell proliferation. SCF caused a statistically significant increase in the number of germ cells positive for bromodeoxyuridine (BrdUrd), indicating that SCF promoted survival and/or stimulated proliferation of the remaining germ cells. We conclude that SCF expression is disrupted after 2,5-HD-induced testicular atrophy and that exogenous administration of SCF promotes recovery of spermatogenesis.
authors.affiliation: Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: E K
authors.initials: EK
authors.lastname: Allard
authors.forename: K T
authors.initials: KT
authors.lastname: Blanchard
authors.forename: K
authors.initials: K
authors.lastname: Boekelheide
mesh_terms: D000818:Animals; D017209:Apoptosis; D001284:Atrophy; D001483:Base Sequence; D002455:Cell Division; D018920:Coculture Techniques; D004305:Dose-Response Relationship, Drug; D006588:Hexanones / Q000633:toxicity*; D008297:Male; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013094:Spermatozoa / Q000473:pathology; D019089:Stem Cell Factor / Q000008:administration & dosage* / Q000235:genetics / Q000502:physiology*; D013733:Testicular Diseases / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology*; D013737:Testis / Q000187:drug effects / Q000473:pathology*
chemical_list: D006588:Hexanones; D012333:RNA, Messenger; D019089:Stem Cell Factor; C011269:2,5-hexanedione