Mechanism of action of l-CDB-4022, a potential nonhormonal male contraceptive, in the seminiferous epithelium of the rat testis.
The present study was conducted to elucidate the possible molecular mechanisms involved in the antispermatogenic activity of l-CDB-4022, an indenopyridine. In this study 45-d-old male Sprague-Dawley rats were treated with a single oral dose of l-CDB-4022 (2.5 mg/kg) or vehicle, and blood and testes were collected at various time points. The rate of body weight gain was not affected, but a significant loss of testes weight was induced by l-CDB-4022. Serum hormones were assayed using specific RIAs or ELISAs, and testicular protein and RNA were analyzed by Western blotting and RT-PCR, respectively. There was a significant decrease in inhibin B and concomitant increase in FSH in serum from l-CDB-4022-treated rats, but serum levels of activin A, testosterone, and LH were unchanged. Western analysis of testicular lysates from l-CDB-4022-treated rats exhibited phosphorylation of ERK1/2 at 4 h and later time points. Loss of nectin/afadin complex occurred at 48 h, but there was an increase in levels of integrin-beta1, N-cadherin, alpha-catenin, and beta-catenin protein at 24 h and later time points. Increase in expression of Fas ligand and Fas receptor was detected 8 and 24 h after l-CDB-4022 treatment. The ratio of the membrane to soluble form of stem cell factor mRNA was decreased. Immunohistochemical analysis of testicular sections indicated a dramatic disruption of the Sertoli cell microtubule network in l-CDB-4022-treated rats. Collectively, these results suggest that l-CDB-4022 activates the MAPK pathway, reduces expression of prosurvival factors such as the membrane form of stem cell factor, alters expression of Sertoli-germ cell adherens junction proteins, disrupts Sertoli cell microtubule structure, and induces the proapoptotic factor, Fas, culminating in germ cell loss from the seminiferous epithelium.
Koduri
Sailaja
S
Division of Reproductive Endocrinology and Toxicology, BIOQUAL Inc., 9600 Medical Center Drive, Rockville, MD 20850-3336, USA. skoduri@bioqual.com
Hild
Sheri Ann
SA
Pessaint
Laurent
L
Reel
Jerry R
JR
Attardi
Barbara J
BJ
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D003272:Contraceptive Agents, Male / Q000494:pharmacology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology; D005640:Follicle Stimulating Hormone / Q000097:blood; D007192:Indenes / Q000494:pharmacology*; D020935:MAP Kinase Signaling System; D008297:Male; D008870:Microtubules / Q000187:drug effects; D010880:Piperidines / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012670:Seminiferous Epithelium / Q000187:drug effects*; D019089:Stem Cell Factor / Q000235:genetics; D019014:fas Receptor / Q000502:physiology
C435918:CDB 4022; D003272:Contraceptive Agents, Male; D007192:Indenes; D010880:Piperidines; D019089:Stem Cell Factor; D019014:fas Receptor; D005640:Follicle Stimulating Hormone; D048049:Extracellular Signal-Regulated MAP Kinases