Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Immature rat ovaries increase their secretion of estradiol (E2) when stimulated by gonadotropins but only after a lag period of several hours. Once established, estrogen secretion can be maintained, or increased, by the continued presence of gonadotropin. A combination of ovine FSH+LH given at 2 hr intervals stimulated the estrogen synthesizing system (ESS) of the ovary and serum E2 showed a pronounced rise between 16 and 20 hrs after the initial injection. When given every 2 hrs for 5 doses (0-8 hrs) serum E2 was undetectable. However, it was increased if 20 IU PMS was injected at the time of the last dose of FSH+LH. Endogenous FSH+LH, increased by hourly injections of LH-releasing hormone for a period of 8 hrs, stimulated the ESS: serum E2 increased at the expected when this treatment was followed by an injection of PMS. Anti-PMS antiserum given 12 hrs after PMS, prevented the expected rise in serum E2 at 24 hrs. However, FSH, LH or a combination of the two given every 2 hrs beginning at the time of the anti-PMS produced an increase in E2 secretion; the combination was more effective than either hormone alone. These results are consistent with the interpretation that a combined FSH-LH action is responsible for induction fo the ESS in the immature rat ovary. The combination of homones is also very effective in maintaining estrogen secretion but some function appears possible with FSH or LH alone.
Steroids 1976 Apr
PMID:Stimulation of the estrogen synthesizing system of the immature rat ovary by exogenous and endogenous gonadotropins. 77 88

Immature hypophysectomized rats were injected with PMS; some groups received hCG 48h later. The C17,20-lyase activity in the granulosa cells removed from the large preovulatory follicles was estimated by the amount of labelled acetic acid produced from 21 (14C) progesterone or 17-hydroxyprogesterone. 17 alpha-hydroxylase and aromatase activity were measured by the tritium exchange method. Although the granulosa cells contained lyase, it was considerably less than their hydroxylase activity. The remaining tissue, consisting of small follicles and hypertrophied thecal and interstitial tissue, had a great deal more lyase and hydroxylase activity than did the granulosa cells. The results are consistent with the view that granulosa cells can produce estrogen from progesterone and do not require androgen precursors from the theca and/or interstitium.
Steroids 1983 Nov
PMID:The C17,20-lyase, 17 alpha-hydroxylase and aromatase activity in rat ovarian granulosa cells stimulated in vivo by gonadotropins. 668 Sep 30

Immature hypophysectomized rats were injected with 2mg of diethylstilbestrol to increase granulosa cell numbers and with 20 IU of PMS to stimulate ovarian growth. Steroid 17 alpha-hydroxylase activity of cultured granulosa cell, harvested from mature follicles 48 h after injection of PMS, was demonstrated using a tritium exchange assay with 17 alpha 3H-pregneneolone as substrate. For comparison, aromatase activity of the same cells was examined by a similar assay using 1 beta 3H-testosterone as the substrate. The activities of the two enzymes were similar when expressed in terms of the amount of substrate converted per unit time. While an NADPH generating system in the incubation medium was essential for demonstrating any hydroxylase activity, 10-15% of the total aromatase activity could be found without added cofactor. Attempts to alter hydroxylase activity of granulosa cells by inclusion of LH, FSH or prolactin in the incubation medium were unsuccessful. However, activity could be change by prostaglandins (PG) or agents which can alter PG synthesis. Activity was increased by low concentrations of phospholipase A2 (PLA2), histamine, and arachidonic acid (AA). Large doses of PLA2, or AA, were inhibitory. PGE2, but not PGF2 alpha, increased, while indomethacin decreased, hydroxylase activity. The results clearly indicate that granulosa cells in the rat have a potent 17-hydroxylase system and therefore do not support the widely held contention that lack of this enzyme is one of the bases for the need for two kinds of cells for ovarian estrogen production.
Steroids 1981 Nov
PMID:Steroid 17 alpha-hydroxylase activity of ovarian granulosa cells from hypophysectomized immature rats treated with pregnant mare's serum gonadotropin (PMS). 679 17