Distribution and regulation by oestrogen of fully processed and variant transcripts of gonadotropin releasing hormone I and gonadotropin releasing hormone receptor mRNAs in the male chicken.
The aim of this study was to increase understanding of the occurrence and regulation of chicken gonadotropin releasing hormone I (cGnRH I) and chicken gonadotropin releasing hormone receptor (cGnRH-R) mRNA variants in the hypothalamic-pituitary-testicular axis (HPTA). The study was carried out in the cockerel. Fully processed cGnRH I mRNA (cGnRH Ia) and a variant transcript (cGnRH Ib) with a retained intron 1 were observed in the preoptic/anterior hypothalamus (POA), the basal hypothalamus, anterior pituitary gland, and testes. Fully processed cGnRH-R mRNA (cGnRH-Ra) and a variant transcript (cGnRH-Rb) with a deletion were detected in the same tissues. In juvenile cockerels, concentrations of cGnRH Ia and b in the POA increased after castration, and this was prevented by oestrogen treatment. In the anterior pituitary gland, the concentration of cGnRH-Ra increased after castration and this was reversed by oestrogen treatment. In intact adult cockerels, oestrogen treatment depressed plasma luteinizing hormone but did not affect concentrations of cGnRH I and cGnRH-R mRNAs in the POA, basal hypothalamus, and anterior pituitary gland, suggesting that locally produced oestrogen, by aromatization, may exert maximal suppression on cGnRH I and GnRH-R mRNAs. In intact adult cockerels, the concentrations of cGnRH Ia and b in the testis, but not cGnRH-Ra and b, were depressed by oestrogen treatment. It was concluded that fully processed and variant cGnRH I and cGnRH-R mRNAs occur in all components of the HPTA. Oestrogen appears to play a role in the regulation of cGnRH Ia and b in the POA and testes, and of cGnRH-Ra in the POA and anterior pituitary gland.
Sun
Y M
YM
Division of Integrative Biology, Roslin Institute, Roslin, Midlothian, UK. yuhman.sun@bbsrc.ac.uk
Dunn
I C
IC
Baines
E
E
Talbot
R T
RT
Illing
N
N
Millar
R P
RP
Sharp
P J
PJ
D000367:Age Factors; D000818:Animals; D001483:Base Sequence; D002645:Chickens; D017931:DNA Primers; D004967:Estrogens / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D014644:Genetic Variation; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis / Q000235:genetics*; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008969:Molecular Sequence Data; D009919:Orchiectomy; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000502:physiology*; D016133:Polymerase Chain Reaction / Q000379:methods; D012323:RNA Processing, Post-Transcriptional / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D011966:Receptors, LHRH / Q000235:genetics*; D013737:Testis / Q000737:chemistry / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects* / Q000502:physiology
D017931:DNA Primers; D004967:Estrogens; D012333:RNA, Messenger; D011966:Receptors, LHRH; D007987:Gonadotropin-Releasing Hormone