The effect of sex steroids on the degradation of LRH by hypothalamic homogenates.
Extract of hypothalami was prepared which contained peptidase capable of degrading LRH. The degradation of LRH by this extract either alone or under the influence of oestrogens, androgens and cholesterol, when added to the extract was measured. Oestrone, oestradiol and oestriol (1 pg to 100 pg) stimulated mean peptidase activity significantly (P less than 0.001) in a dose-dependent manner. Testosterone (0.1 ng to 10 ng) also caused a dose-dependent increase in degradation of LRH, the two highest doses used significantly increasing the mean activity (P less than 0.001). Only the highest dose of androstenedione (10 ng) or dehydroepiandrosterone (10 ng) caused a significant increase of the mean LRH degradation (P less than 0.05). Neither cholesterol nor dihydrotestosterone increased peptidase activity when added to the extract. It is suggested that it is possible that these peptidase enzymes could occupy a role in the negative feedback of steroids on the hypothalamus.
D000728:Androgens / Q000494:pharmacology*; D000735:Androstenedione / Q000494:pharmacology; D000818:Animals; D002784:Cholesterol / Q000494:pharmacology; D003687:Dehydroepiandrosterone / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D004964:Estriol / Q000494:pharmacology; D004967:Estrogens / Q000378:metabolism / Q000494:pharmacology*; D004970:Estrone / Q000494:pharmacology; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000494:pharmacology; D012756:Sheep; D013739:Testosterone / Q000378:metabolism / Q000494:pharmacology
D000728:Androgens; D004967:Estrogens; D004970:Estrone; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D000735:Androstenedione; D003687:Dehydroepiandrosterone; D004958:Estradiol; D002784:Cholesterol; D010447:Peptide Hydrolases; D004964:Estriol