TY - JOUR
T1 - Reduction of LH-RH pituitary and estradiol uterine binding sites by a superactive analog of luteinizing hormone-releasing hormone
AU - Pedroza, E.
AU - Vilchez-Martinez, J. A.
AU - Coy, D. H.
AU - Arimura, A.
AU - Schally, A. V.
PY - 1980/1/1
Y1 - 1980/1/1
N2 - The ability of the Luteinizing Hormone-Releasing Hormone (LH-RH) analogs to displace LH-RH from its pituitary receptors was evaluated in vitro. The two superactive analogs tested showed higher potency than the antagonists and LH-RH itself, D-Trp6-LH-RH being the most potent. The LH-RH specific binding activity in the pituitary fluctuated throughout the age of the rats. The highest number of LH-RH binding sites were seen on day 35 of age (276 fmol x 10-2/pit) and an increment was induced by 0.05 μg D-Trp6-LH-RH (400 fmol x 10-2/pit). However, 1 μg D-Trp6-LH-RH reduced the binding of LH-RH at all the times studied. In the control animals the number of estradiol binding sites increased on day 42 of age, and 0.05 μg D-Trp6-LH-RH augmented them on day 35 of age. On the contrary, 1 μg D-Trp6-LH-RH diminished the estradiol uterine receptors at all the times studied. Similar results were obtained in the ovariectomized-hypophysectomized rats on day 35 of age. Our studies demonstrated a biphasic action of D-Trp6-LH-RH on LH-RH pituitary receptors and a direct effect on uterus which could be mediated through the uterine estradiol receptors.
AB - The ability of the Luteinizing Hormone-Releasing Hormone (LH-RH) analogs to displace LH-RH from its pituitary receptors was evaluated in vitro. The two superactive analogs tested showed higher potency than the antagonists and LH-RH itself, D-Trp6-LH-RH being the most potent. The LH-RH specific binding activity in the pituitary fluctuated throughout the age of the rats. The highest number of LH-RH binding sites were seen on day 35 of age (276 fmol x 10-2/pit) and an increment was induced by 0.05 μg D-Trp6-LH-RH (400 fmol x 10-2/pit). However, 1 μg D-Trp6-LH-RH reduced the binding of LH-RH at all the times studied. In the control animals the number of estradiol binding sites increased on day 42 of age, and 0.05 μg D-Trp6-LH-RH augmented them on day 35 of age. On the contrary, 1 μg D-Trp6-LH-RH diminished the estradiol uterine receptors at all the times studied. Similar results were obtained in the ovariectomized-hypophysectomized rats on day 35 of age. Our studies demonstrated a biphasic action of D-Trp6-LH-RH on LH-RH pituitary receptors and a direct effect on uterus which could be mediated through the uterine estradiol receptors.
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U2 - 10.1016/0006-291X(80)91580-6
DO - 10.1016/0006-291X(80)91580-6
M3 - Article
C2 - 6251826
AN - SCOPUS:0019310010
VL - 95
SP - 1056
EP - 1062
JO - Topics in Catalysis
JF - Topics in Catalysis
IS - 3
ER -