TY - JOUR
T1 - Direct effect of the luteinizing hormone releasing hormone analog D-Trp6-Pro9-Net-LHRH on rat ovarian steroidogenesis
AU - Malozowski, S.
AU - Cassorla, F.
AU - Gelato, M.
AU - Nicoletti, M.
AU - D'Agata, R.
AU - Mericq, V.
AU - Loriaux, D.
PY - 1985
Y1 - 1985
N2 - The luteinizing hormone releasing hormone analog D-Trp6-Pro9-Net-LHRH (LHRH(a)) inhibits rat ovarian estradiol secretion. To determine whether LHRH(a) decreases serum estradiol concentrations solely by inhibiting gonadotropin secretion or, in addition, by influencing directly ovarian estradiol biosynthesis, we examined the effects of LHRH(a) on the activities of 5 key ovarian steroidogenic enzymes. Fifty hypophysectomized, gonadotropin-treated rats were given either LHRH(a) (1 μg/day) or saline sc during 7 days. The LHRH(a) treated animals exhibited a significant decrease in serum estradiol when compared with the control group (461 ± 30 vs 31 ± 5 pg/ml, mean ± SE, P<0.001). The changes in estradiol concentration were associated with decreases in ovarian weight (372 ± 19 vs 185 ± 11 mg, P<0.001) and in the microsomal enzyme activities of 3β-hydroxysteroid dehydrogenase (156 ± 5 vs 53 ± 4 nmol/mg prot/min, P<0.001), 17 hydroxylase (4.7 ± 0.8 vs 3.7 ± 0.7 nmol/mg prot/min, P<0.002), 17,20 desmolase (279 ± 14 vs 50 ± 7 pmol/mg prot/min, P<0.001), 17 ketosteroid reductase (132 ± 11 vs 6 ± 1 nmol/mg prot/min, P<0.001), and aromatase (19 ± 1.5 vs 0.9 ± 0.1 nmol/mg prot/min, P<0.001) in LHRH(a) treated animals. These findings indicate that LHRH(a) can inhibit directly rat ovarian estradiol biosynthesis.
AB - The luteinizing hormone releasing hormone analog D-Trp6-Pro9-Net-LHRH (LHRH(a)) inhibits rat ovarian estradiol secretion. To determine whether LHRH(a) decreases serum estradiol concentrations solely by inhibiting gonadotropin secretion or, in addition, by influencing directly ovarian estradiol biosynthesis, we examined the effects of LHRH(a) on the activities of 5 key ovarian steroidogenic enzymes. Fifty hypophysectomized, gonadotropin-treated rats were given either LHRH(a) (1 μg/day) or saline sc during 7 days. The LHRH(a) treated animals exhibited a significant decrease in serum estradiol when compared with the control group (461 ± 30 vs 31 ± 5 pg/ml, mean ± SE, P<0.001). The changes in estradiol concentration were associated with decreases in ovarian weight (372 ± 19 vs 185 ± 11 mg, P<0.001) and in the microsomal enzyme activities of 3β-hydroxysteroid dehydrogenase (156 ± 5 vs 53 ± 4 nmol/mg prot/min, P<0.001), 17 hydroxylase (4.7 ± 0.8 vs 3.7 ± 0.7 nmol/mg prot/min, P<0.002), 17,20 desmolase (279 ± 14 vs 50 ± 7 pmol/mg prot/min, P<0.001), 17 ketosteroid reductase (132 ± 11 vs 6 ± 1 nmol/mg prot/min, P<0.001), and aromatase (19 ± 1.5 vs 0.9 ± 0.1 nmol/mg prot/min, P<0.001) in LHRH(a) treated animals. These findings indicate that LHRH(a) can inhibit directly rat ovarian estradiol biosynthesis.
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U2 - 10.1055/s-2007-1013533
DO - 10.1055/s-2007-1013533
M3 - Article
C2 - 3894195
AN - SCOPUS:0021850133
VL - 17
SP - 321
EP - 322
JO - Hormone and Metabolic Research
JF - Hormone and Metabolic Research
SN - 0018-5043
IS - 6
ER -