Blocking of progestin action disrupts spermatogenesis in Nile tilapia (Oreochromis niloticus).
In vitro studies have indicated that the maturation-inducing hormone 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DP, DHP), probably through nuclear progestin receptor (Pgr), might be involved in the proliferation of spermatogonial cells and the initiation of meiosis in several fish species. However, further in vivo evidence is required to elucidate the role of DHP in spermatogenesis during sexual differentiation in teleosts. In this study, we cloned pgr and analyzed its expression in Nile tilapia (Oreochromis niloticus) and treated XY fish with RU486 (a synthetic Pgr antagonist) from 5 days after hatching (dah) to determine the role of DHP in spermatogenesis. Sequence and phylogenetic analyses revealed that the Pgr identified in tilapia is a genuine Pgr. Pgr was found to be expressed in the Sertoli cells surrounding spermatogonia and spermatids in the testis of tilapia. Real-time PCR analysis revealed that the expression of pgr in the testis was significantly upregulated from 10 dah, further increased at 50 dah, and persisted until adulthood in fish. In the testis of RU486-treated fish, the transcript levels of germ cell markers and a meiotic marker were substantially reduced. However, the expression of markers in Sertoli cells remained unchanged. Moreover, the production of 11-ketotestosterone and the expression of genes encoding various steroidogenic enzymes were also not altered. In contrast, the expression of cyp17a2, encoding one of the critical steroidogenic enzymes involved in DHP biosynthesis, declined significantly, possibly indicating the inhibition of DHP production by RU486. RU486 treatment given for 2 months did not affect spermatogenesis; however, treatment given for more than 3 months resulted in a decrease in spermatogonial cell numbers and depletion of later-phase spermatogenic cells. Simultaneous excessive DHP supplementation restored spermatogenesis in RU486-treated XY fish. Taken together, our data further indicated that DHP, possibly through Pgr, might be essential for spermatogonial cell proliferation and spermatogenesis in fish.
Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education)Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing 400715, People's Republic of China.
Gang
G
Liu
Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education)Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing 400715, People's Republic of China.
Feng
F
Luo
Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education)Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing 400715, People's Republic of China.
Qiang
Q
Song
Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education)Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing 400715, People's Republic of China.
Limin
L
Wu
Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education)Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing 400715, People's Republic of China.
Yongxiu
Y
Qiu
Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education)Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing 400715, People's Republic of China.
Hongjuan
H
Shi
Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education)Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing 400715, People's Republic of China yanlinzhou916@126.com wdeshou@swu.edu.cn.
Deshou
D
Wang
Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education)Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Chongqing 400715, People's Republic of China yanlinzhou916@126.com wdeshou@swu.edu.cn.
Linyan
L
Zhou
D000595:Amino Acid Sequence; D000818:Animals; D023681:Cichlids / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D003001:Cloning, Molecular; D029941:Fish Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D006727:Hormone Antagonists / Q000494:pharmacology; D006908:Hydroxyprogesterones / Q000378:metabolism / Q000494:pharmacology; D008297:Male; D015735:Mifepristone / Q000494:pharmacology; D008969:Molecular Sequence Data; D010802:Phylogeny; D011372:Progestins / Q000037:antagonists & inhibitors*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011980:Receptors, Progesterone / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D013091:Spermatogenesis / Q000187:drug effects* / Q000502:physiology*; D013737:Testis / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D013739:Testosterone / Q000031:analogs & derivatives / Q000097:blood / Q000494:pharmacology
D029941:Fish Proteins; D006727:Hormone Antagonists; D006908:Hydroxyprogesterones; D011372:Progestins; D012333:RNA, Messenger; D011980:Receptors, Progesterone; C007433:17,20-dihydroxy-4-pregnen-3-one; D015735:Mifepristone; D013739:Testosterone; C003600:11-ketotestosterone
DHP; Pgr; RU486 treatment; spermatogenesis