TY - JOUR
T1 - Differential regulation of gonadotropin subunit messenger ribonucleic acids by gonadotropin- releasing hormone pulse frequency in ewes
AU - Leung, K.
AU - Kaynard, Alan H.
AU - Negrini, Bryan P.
AU - Kim, Kyoon E.
AU - Maurer, Richard A.
AU - Landefeld, Thomas D.
PY - 1987/10
Y1 - 1987/10
N2 - Changes in the frequency of GnRH and LH pulses have been shown to occur between the luteal and preovulatory periods in the ovine estrous cycle. We examined the effect of these different frequencies of GnRH pulses on pituitary concentrations of LH and FSH subunit mRNAs. Eighteen ovariectomized ewes were implanted with progesterone to eliminate endogenous GnRH release during the nonbreeding season. These animals then received 3 ng/kg body weight GnRH in frequencies of once every 4, 1, or 0.5 h for 4 days. These frequencies represent those observed during the luteal and follicular phases, and the preovulatory LH and FSH surge of the ovine estrous cycle, respectively. On day 4, the ewes were killed and their anterior pituitary glands were removed for measurements of pituitary LH, FSH, and their subunit mRNAs. Pituitary content of LH and FSH, as assessed by RIA, did not change (P > 0.10) in response to the three different GnRH pulse frequencies. However, subunit mRNA concentrations, assessed by solution hybridization assays and expressed as femtomoles per mg total RNA, did change as a result of different GnRH frequencies. amRNA concentrations were higher (P < 0.05) when the GnRH pulse frequency was 1/0.5 h and 1 h, whereas LHβ and FSHβ mRNA concentrations were maximal (P < 0.05) only at a pulse frequency of 1/h. Additionally, pituitary LH and FSH secretory response to GnRH on day 4 was maximal (P = 0.05) when the pulse infusion was 1/h. We conclude that different frequencies of GnRH pulses can regulate α- and β-subunits of LH and FSH in a differential fashion. Furthermore, the ability of the pituitary gland to secrete LH and FSH in response to GnRH may be related to LH and FSH β-subunit mRNA concentrations.
AB - Changes in the frequency of GnRH and LH pulses have been shown to occur between the luteal and preovulatory periods in the ovine estrous cycle. We examined the effect of these different frequencies of GnRH pulses on pituitary concentrations of LH and FSH subunit mRNAs. Eighteen ovariectomized ewes were implanted with progesterone to eliminate endogenous GnRH release during the nonbreeding season. These animals then received 3 ng/kg body weight GnRH in frequencies of once every 4, 1, or 0.5 h for 4 days. These frequencies represent those observed during the luteal and follicular phases, and the preovulatory LH and FSH surge of the ovine estrous cycle, respectively. On day 4, the ewes were killed and their anterior pituitary glands were removed for measurements of pituitary LH, FSH, and their subunit mRNAs. Pituitary content of LH and FSH, as assessed by RIA, did not change (P > 0.10) in response to the three different GnRH pulse frequencies. However, subunit mRNA concentrations, assessed by solution hybridization assays and expressed as femtomoles per mg total RNA, did change as a result of different GnRH frequencies. amRNA concentrations were higher (P < 0.05) when the GnRH pulse frequency was 1/0.5 h and 1 h, whereas LHβ and FSHβ mRNA concentrations were maximal (P < 0.05) only at a pulse frequency of 1/h. Additionally, pituitary LH and FSH secretory response to GnRH on day 4 was maximal (P = 0.05) when the pulse infusion was 1/h. We conclude that different frequencies of GnRH pulses can regulate α- and β-subunits of LH and FSH in a differential fashion. Furthermore, the ability of the pituitary gland to secrete LH and FSH in response to GnRH may be related to LH and FSH β-subunit mRNA concentrations.
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U2 - 10.1210/mend-1-10-724
DO - 10.1210/mend-1-10-724
M3 - Article
C2 - 2484713
AN - SCOPUS:0023640280
SN - 0888-8809
VL - 1
SP - 724
EP - 728
JO - Molecular Endocrinology
JF - Molecular Endocrinology
IS - 10
ER -