Gonadotropin regulation of NGFI-B messenger ribonucleic acid expression during ovarian follicle development in the rat.
NGFI-B is an immediate-early gene that encodes an orphan nuclear receptor. The present study was designed to examine the localization and gonadotropin regulation of NGFI-B expression in the rat ovary. Northern blot analysis of ovaries obtained from prepubertal rats revealed the increased expression of NGFI-B during prepubertal development. Treatment of immature rats with PMSG, however, decreased ovarian NGFI-B expression. The major cell types expressing NGFI-B messenger RNA were thecal cells of follicles in different sizes. In contrast, treatment of PMSG-primed rats with human (h) CG resulted in the rapid and transient stimulation of ovarian NGFI-B messenger RNA, reaching a peak within 1 h. In situ hybridization analysis revealed that hCG treatment induced the expression of NGFI-B in granulosa cells of preovulatory follicles. Treatment of cultured preovulatory follicles in vitro with LH further confirmed the time- and dose-dependent stimulation of NGFI-B messenger RNA and protein. LH-stimulated NGFI-B expression in preovulatory follicles was abolished by alpha-amanitin, but was superinduced by cycloheximide. Furthermore, treatment of adult cycling rats with pentobarbital abolished NGFI-B expression on proestrus, and exogenous administration of hCG restored it, indicating the role of the preovulatory surge of LH in the stimulation of NGFI-B expression. These results demonstrate the cell type-specific expression and gonadotropin induction of NGFI-B in granulosa cells of preovulatory follicles and suggest a role for NGFI-B in the ovulatory process.
Park
J I
JI
Hormone Research Center, Chonnam National University, Kwangju 500-757, Korea.
Park
H J
HJ
Choi
H S
HS
Lee
K
K
Lee
W K
WK
Chun
S Y
SY
D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D046508:Culture Techniques; D004268:DNA-Binding Proteins / Q000235:genetics*; D004971:Estrus / Q000502:physiology; D005260:Female; D005498:Follicular Phase / Q000502:physiology; D006062:Gonadotropins / Q000502:physiology*; D006064:Gonadotropins, Equine / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000494:pharmacology; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D006080:Ovarian Follicle / Q000187:drug effects / Q000502:physiology*; D010053:Ovary / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D012756:Sheep; D014157:Transcription Factors / Q000235:genetics*
D006063:Chorionic Gonadotropin; D004268:DNA-Binding Proteins; D006062:Gonadotropins; D006064:Gonadotropins, Equine; C539821:NR4A1 protein, human; C539820:Nr4a1 protein, rat; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D014157:Transcription Factors; D007986:Luteinizing Hormone