The chicken pituitary-specific transcription factor PIT-1 is involved in the hypothalamic regulation of pituitary hormones.
Pit-1 is a pituitary-specific POU-domain DNA binding factor, which binds to and trans-activates promoters of growth hormone- (GH), prolactin- (PRL) and thyroid stimulating hormone-beta- (TSHbeta) encoding genes. Thyrotropin-releasing hormone (TRH) is located in the hypothalamus and stimulates TSH, GH and PRL release from the pituitary gland. In the present study, we successfully used the cell aggregate culture system for chicken pituitary cells to study the effect of TRH administration on the ggPit-l* (chicken Pit-1), GH and TSHbeta mRNA expression in vitro. In pituitary cell aggregates of 11-day-old male broiler chicks the ggPit-l * mRNA expression was significantly increased following TRH administration, indicating that the stimulatory effects of TRH on several pituitary hormones are mediated via its effect on the ggPit-l* gene expression. Therefore, a semiquantitative RT-PCR method was used to detect possible changes in GH and TSHbeta mRNA levels. TRH affected both the GH and TSHbeta mRNA levels. The results of this in vitro study reveal that ggPit-1 * has a role in mediating the stimulatory effects of TRH on pituitary hormones like GH and TSHbeta in the chicken pituitary.
Van As
P
P
Division of Livestock-Nutrition-Quality, Department of Biosystems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, Kasteelpark Arenberg 30, B-3001, Leuven, Belgium. Pieter.vanAs@wur.nl
Janssens
K
K
Pals
K
K
De Groef
B
B
Onagbesan
O M
OM
Bruggeman
V
V
Darras
V M
VM
Denef
C
C
Decuypere
E
E
D000818:Animals; D002460:Cell Line; D002645:Chickens; D017931:DNA Primers; D005786:Gene Expression Regulation; D013006:Growth Hormone / Q000096:biosynthesis / Q000235:genetics; D007030:Hypothalamo-Hypophyseal System; D008297:Male; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D037322:Thyrotropin, beta Subunit / Q000096:biosynthesis / Q000235:genetics; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*; D050817:Transcription Factor Pit-1 / Q000096:biosynthesis* / Q000187:drug effects
D017931:DNA Primers; D012333:RNA, Messenger; D037322:Thyrotropin, beta Subunit; D050817:Transcription Factor Pit-1; D013973:Thyrotropin-Releasing Hormone; D013006:Growth Hormone