TY - JOUR
T1 - Regulation of genes encoding steroidogenic factor-1 (SF-1) and gonadotropin subunits in the ovine pituitary gland
AU - Baratta, M.
AU - Turzillo, A. M.
AU - Arreguin-Arevalo, A.
AU - Clay, C. M.
AU - Nett, T. M.
N1 - Funding Information:
We express our gratitude to M. Royals and K. Suter for assistance with treatments and tissue collections, and M. Gallegos for management and care of ewes. This work was supported by USDA grant 95-37203-1997.
PY - 2003/7
Y1 - 2003/7
N2 - Steroidogenic factor-1 (SF-1) is a transcription factor originally characterized as a mediator of gene expression in steroidogenic tissues. Studies in SF-1 knockout mice revealed that SF-1 has additional roles at multiple levels of the hypothalamic-pituitary-gonadal axis, including regulation of gene expression in pituitary gonadotropes. Specific binding sites for SF-1 have been demonstrated in several pituitary genes with essential roles in gonadotropin synthesis, including α subunit, LHβ subunit, and GnRH receptor. In studies aimed at identifying physiological factors controlling pituitary expression of SF-1, GnRH has been implicated as a co-regulator of SF-1 and gonadotropin subunit genes. In both rats and ewes, elevated endogenous secretion of GnRH following ovariectomy was associated with increased amounts of SF-1 mRNA in the anterior pituitary gland. Conversely, removal of GnRH input to the pituitary gland by hypothalamic-pituitary disconnection (HPD) in ovariectomized (OVX) ewes reduced SF-1 expression. Despite these changes, however, treatment of OVX ewes with GnRH following HPD only partially restored levels of SF-1 mRNA in the pituitary gland. Therefore, it is possible that regulation of SF-1 gene expression by GnRH during the estrous cycle may involve ovarian hormones or other hypothalamic factors. Additional studies are required to further define the physiological roles of SF-1 in regulation of the hypothalamic-pituitary-gonadal axis in domestic ruminants.
AB - Steroidogenic factor-1 (SF-1) is a transcription factor originally characterized as a mediator of gene expression in steroidogenic tissues. Studies in SF-1 knockout mice revealed that SF-1 has additional roles at multiple levels of the hypothalamic-pituitary-gonadal axis, including regulation of gene expression in pituitary gonadotropes. Specific binding sites for SF-1 have been demonstrated in several pituitary genes with essential roles in gonadotropin synthesis, including α subunit, LHβ subunit, and GnRH receptor. In studies aimed at identifying physiological factors controlling pituitary expression of SF-1, GnRH has been implicated as a co-regulator of SF-1 and gonadotropin subunit genes. In both rats and ewes, elevated endogenous secretion of GnRH following ovariectomy was associated with increased amounts of SF-1 mRNA in the anterior pituitary gland. Conversely, removal of GnRH input to the pituitary gland by hypothalamic-pituitary disconnection (HPD) in ovariectomized (OVX) ewes reduced SF-1 expression. Despite these changes, however, treatment of OVX ewes with GnRH following HPD only partially restored levels of SF-1 mRNA in the pituitary gland. Therefore, it is possible that regulation of SF-1 gene expression by GnRH during the estrous cycle may involve ovarian hormones or other hypothalamic factors. Additional studies are required to further define the physiological roles of SF-1 in regulation of the hypothalamic-pituitary-gonadal axis in domestic ruminants.
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U2 - 10.1016/S0739-7240(03)00051-1
DO - 10.1016/S0739-7240(03)00051-1
M3 - Article
C2 - 12963105
AN - SCOPUS:0141570983
SN - 0739-7240
VL - 25
SP - 121
EP - 131
JO - Domestic Animal Endocrinology
JF - Domestic Animal Endocrinology
IS - 1
ER -