17 alpha,20 alpha-Dihydroxy-4-pregnen-3-one is the naturally occurring spermiation-inducing hormone in the testis of a frog, Rana nigromaculata.
Spermiation, the process in which vertebrate spermatozoa are detached from investing Sertoli cells into the lumen of the seminiferous tubule, is a prerequisite for the successful fertilization. Using an in vitro Rana nigromaculata spermiation bioassay, we have shown that gonadotropin initiates spermiation by inducing the synthesis of delta 4-steroids by testis fragments. Among all of the delta 4-steroid metabolites produced by R. nigromaculata testis fragments, spermiation-inducing activity was confined to only one metabolite; this metabolite was identified as 17 alpha,20 alpha-dihydroxy-4-pregnen-3-one (17 alpha,20 alpha-DP). Induction of spermiation by gonadotropin in vitro was accompanied by marked elevations in 17 alpha,20 alpha-DP concentrations in incubation media. These findings provide evidence that 17 alpha,20 alpha-DP is the nautrally occurring spermiation-inducing hormone in R. nigromaculata.
Kobayashi
T
T
Biological Institute, Faculty of Science, Niigata University, Japan.
Sakai
N
N
Adachi
S
S
Asahina
K
K
Iwasawa
H
H
Nagahama
Y
Y
D019326:17-alpha-Hydroxyprogesterone; D000818:Animals; D001681:Biological Assay; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D003489:Cyanoketone / Q000494:pharmacology; D006908:Hydroxyprogesterones / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D008854:Microscopy, Electron; D011374:Progesterone / Q000378:metabolism; D011898:Ranidae; D013091:Spermatogenesis / Q000187:drug effects*; D013737:Testis / Q000187:drug effects / Q000378:metabolism
D006063:Chorionic Gonadotropin; D006908:Hydroxyprogesterones; C007433:17,20-dihydroxy-4-pregnen-3-one; D003489:Cyanoketone; D011374:Progesterone; D019326:17-alpha-Hydroxyprogesterone