title: Mouse model of male germ cell apoptosis in response to a lack of hormonal stimulation.
abstract: As a prerequisite for studies using mutant mice, we established a mouse model for induction of male germ cell apoptosis after deprivation of gonadotropins and intratesticular testosterone (T). We employed a potent long acting gonadotropin-releasing hormone antagonist (GnRH-A), acyline, alone or in combination with an antiandrogen, flutamide for effective induction of germ cell apoptosis in mice. Combined treatment with continuous release of acyline (3 mg/kg BW/day) with flutamide (in the form of sc pellets of 25 mg) resulted in almost the same level of suppression of spermatogenesis, as judged by testis weight and by germ cell apoptotic index, in 2 weeks as that reported for rats after treatment with 1.25 mg/kg BW Nal-Glu GnRH-A for the same time period. Within the study paradigm, the maximum suppression of spermatogenesis occurred after a single sc injection of high (20 mg/kg BW) dose of acyline with flutamide. The combined treatment resulted in complete absence of elongated spermatids. Germ cell counts at stages VII-VIII showed a significant (P < 0.05) reduction in the number of preleptotene (27.1%) and pachytene spermatocytes (81.9%), and round spermatids (96.6%) in acyline + flutamide group in comparison with controls. In fact, treatment with a single high (20 mg/kg BW) dose of acyline combined with flutamide in mice achieved same or greater level of suppression, measured by germ cell counts at stages VII-VIII, in two weeks when compared with those reported after daily treatment with Nal-Glu GnRH-A for 4 weeks in rats. Both plasma and testicular T levels were markedly suppressed after administration of acyline alone either by miniosmotic pump or by a single sc injection. Addition of flutamide to acyline had no discernible effect on plasma or intratesticular T levels when compared with acyline alone. These results demonstrate that optimum suppression of spermatogenesis through increased germ cell death is only possible in mice if total abolition of androgen action is achieved and further emphasize the usefulness of acyline + flutamide treated mice as a suitable model system to study hormonal regulation of testicular germ cell apoptosis.
authors.affiliation: Division of Endocrinology, Department of Medicine, Harbor-UCLA Medical Center, David Geffen School of Medicine at UCLA, California 90509, USA. hikim@labiomed.org
authors.forename: Amiya P Sinha
authors.initials: AP
authors.lastname: Hikim
authors.forename: Yanira
authors.initials: Y
authors.lastname: Vera
authors.forename: Rashid I
authors.initials: RI
authors.lastname: Elhag
authors.forename: Yanhe
authors.initials: Y
authors.lastname: Lue
authors.forename: Yu-Gui
authors.initials: YG
authors.lastname: Cui
authors.forename: Vanisha
authors.initials: V
authors.lastname: Pope
authors.forename: Andrew
authors.initials: A
authors.lastname: Leung
authors.forename: Vince
authors.initials: V
authors.lastname: Atienza
authors.forename: Christina
authors.initials: C
authors.lastname: Wang
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Swerdloff
mesh_terms: D000818:Animals; D017209:Apoptosis; D004249:DNA Damage; D005485:Flutamide / Q000378:metabolism / Q000494:pharmacology; D005854:Germ Cells / Q000166:cytology* / Q000187:drug effects / Q000473:pathology*; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors; D006728:Hormones / Q000378:metabolism*; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007985:Leydig Cells / Q000166:cytology / Q000648:ultrastructure; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains / Q000378:metabolism; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D009842:Oligopeptides / Q000494:pharmacology; D051381:Rats; D012708:Sertoli Cells / Q000473:pathology; D013091:Spermatogenesis; D013737:Testis / Q000473:pathology; D013739:Testosterone / Q000378:metabolism; D013997:Time Factors
chemical_list: D006728:Hormones; D009842:Oligopeptides; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D005485:Flutamide; C109238:acyline