Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Immature female rats received either one injection of 2 mg diethylstilboestrol (DES)/rat subcutaneously and were killed 12 h later or received two injections of DES at 0 and 24 h and were killed at 24, 36 and 48 h after the initial injection. The ovarian follicles were released by enzymic digestion with collagenase and separated into those of small, medium and large diameter (less than 200 microns, 200-400 microns and greater than 400 microns) by filtration through graded Teflon sieves and granulosa cells were extracted from these follicles. The ovaries of immature rats treated with pregnant mares' serum gonadotrophin (PMSG) were used for comparative purposes. Incorporation of [3H]thymidine into granulosa cell DNA was augmented by DES and by PMSG. Small follicles were more strongly stimulated by DES at 12 h than those of other sizes, but rates increased significantly in medium and large follicles at 48 h. Aromatase activity in the DES-treated group was low at all times and in all follicles. Rates of oestrogen and progesterone production in response to 36 h of exposure to follicle-stimulating hormone (FSH) in vitro were significantly lower than in the PMSG-treated group. FSH-stimulated steroid production in the DES group at 36-48 h was lower, particularly in the medium follicles. A significant rise in serum FSH, luteinizing hormone (LH) and progesterone concentrations was noted only at 36 h after DES treatment, while serum and follicular fluid oestrogen values remained unchanged. When these changes were compared with those in PMSG-treated rats, there were obvious differences. The pattern of thymidine incorporation and aromatase activity differed with time and follicle size. Serum FSH and LH values were not affected by PMSG treatment, but serum and follicular fluid oestradiol values increased with time. The PMSG-treated animals ovulated in response to human chorionic gonadotrophin, but the DES-treated rats did not ovulate in spite of the presence of some large antral follicles in the ovaries. These findings show that initial exposure of follicles to high concentrations of oestrogen results in follicles which fail to respond to subsequent gonadotrophin surges and are thereby restricted in their ability to differentiate fully.
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PMID:Regulation of follicular development by diethylstilboestrol in ovaries of immature rats. 190 64

Adipose tissue is a major, nonglandular site for the aromatization of androgens to estrogens. In this tissue, the aromatase activity resides primarily in the stromal cells, and we have used cultures of stromal cells to study the effects of insulin and insulin-like growth factor I (IGF-I) on aromatase activity. Adipose tissue, obtained during indicated surgery, was digested with collagenase, and the stromal cells were isolated and cultured. Aromatase activity was determined by measuring the tritiated water (3H2O) in the medium after incubating stromal cells with [1 beta-3H]androstenedione. Insulin and IGF-I had no effect on the aromatase activity in cultured adipose stromal cells at concentrations of 10 to 1,000 microU/ml. However, insulin (100 to 1,000 microU/ml) and IGF-I (500 ng/ml) markedly attenuated the stimulatory effect of (Bu)2cAMP, but significantly augmented the dexamethasone-stimulated aromatase activity. The greater effects of IGF-I compared with the effect of insulin are compatible with both effects being mediated through the IGF-I compared with the effect of insulin are compatible with both effects being mediated through the IGF-I receptor. In addition, the effects of insulin in attenuating the aromatase activity in adipose tissue could potentiate its role in hyperandrogenic syndromes in women.
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PMID:Aromatase activity in human adipose tissue stromal cells: effect of growth factors. 196 38

The steroidogenic potential of various physiological compartments within the ovary of the hen were examined using in vitro systems. Three-hour incubations of individual whole small follicles (less than 1 mm-1 cm) or 100,000 collagenase-dispersed theca cells of the five largest ovarian follicles (F1-F5) were conducted in 1 ml of Medium 199 at 37 degrees C in the presence and absence of luteinizing hormone (LH) (0.39, 0.78, 1.56, 3.13 and 6.25 ng), progesterone (5 ng), and dehydroepiandrosterone (DHEA, 5 ng). Steroid output was measured by radioimmunoassay of incubation media. Progesterone was not produced by small follicles although they are a major source of DHEA and estradiol and a significant source of androstenedione. Output of DHEA, androstenedione and estradiol was highly stimulated by LH. The substrate for androstenedione and estradiol in small follicles is probably DHEA. Output of DHEA and androstenedione in theca cells of F2-F5 was stimulated by LH in a dose-related manner. A dose-response relationship between estradiol output and the concentration of LH in media was not apparent in theca cells from F2-F5. Steroidogenesis in theca tissue of large follicles occurs predominantly via the delta 4 pathway. The ability of these theca cells to metabolize progesterone to androstenedione is lost between 36 and 12 h before ovulation. Their ability to metabolize DHEA to androstenedione is still present 12 h before ovulation. Aromatase activity is significantly reduced between 36 and 12 h before ovulation. These data indicate that both large and small follicles can be stimulated by LH. The small follicles are the major source of estrogen. As the large yolky follicles mature, steroidogenesis shifts from the delta 5 to the delta 4 pathway. By 12 h before ovulation, the F1 follicle has lost the ability to convert progesterone to androstenedione. The inability of the largest ovarian follicle to convert progesterone to androstenedione contributes at least in part to the preovulatory increase in the plasma concentration of progesterone that generates the preovulatory LH surge by positive feedback.
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PMID:Ovarian steroidogenesis during follicular maturation in the domestic fowl (Gallus domesticus). 295 Sep 35

Clinical evidence suggests that sex hormones affect adipose tissue metabolism and deposition. To investigate the biosynthesis and possible action of estrogen in adipose tissue, we report the use of competitive, specific polymerase chain reaction amplifications to determine levels of estrogen receptor (ER) messenger RNA (mRNA) and cytochrome P450 aromatase mRNA in adipocytes and adipose stromal cells. This extremely sensitive technique uses coamplification of a homologous animal species complementary RNA to control for differences in amplification efficiencies. The DNA amplification products are identified by Southern hybridization with species-specific radiolabeled oligonucleotide probes. Abdominal adipose tissue obtained from female patients during elective abdominoplasty was separated by collagenase digestion and centrifugation into floating adipocytes and pelleted adipose stromal cells. Our results demonstrate higher ER mRNA levels in adipocytes compared to adipose stromal cells, whereas cytochrome P450 aromatase mRNA levels are higher in adipose stromal cells compared to adipocytes. The finding of ER mRNA in adipose tissue suggests the presence of the ER in adipose tissue. In addition the inverse correlation of ER mRNA and cytochrome P450 aromatase mRNA levels in adipocytes and adipose stromal cells suggests a paracrine relationship whereby estrogen produced by adipose stromal cells affects adjacent adipocytes.
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PMID:Determination of estrogen receptor messenger ribonucleic acid (mRNA) and cytochrome P450 aromatase mRNA levels in adipocytes and adipose stromal cells by competitive polymerase chain reaction amplification. 840 52

In addition to the regulation of FSH secretion, it has been clearly shown that inhibin and activin have paracrine/autocrine effects in the gonads. We have studied the effect of human recombinant inhibin A and human recombinant activin A on immature porcine Leydig cells in vitro. Leydig cells were prepared by collagenase digestion of testes from 3-week-old piglets, purified on Percoll gradient, then cultured in a chemically defined medium. The cells were treated with increasing amounts of inhibin A or activin A (0.5-200 ng/ml). Direct application of either inhibin A or activin A on Leydig cells for 4 or 48 h did not stimulate basal testosterone secretion. Conversely, treatment of the cells for 48 h with either factor resulted in a dose-dependent increase in hCG-stimulated testosterone secretion (10[-9] M hCG, 2 h) with a maximal effect of 2.40 +/- 0.37- and 2.43 +/- 0.37-fold increases for inhibin A and activin A, respectively, and these changes were associated with a slight increase in LH/hCG-binding sites (1.37 +/- 0.19- and 1.24 +/- 0.11-fold increases). In addition, both inhibin A and activin A enhanced messenger RNA (mRNA) levels of LH/hCG receptor (2.75 +/- 0.40- and 2.53 +/- 0.60-fold increases) and cytochrome P450 17alpha-hydroxylase (6 +/- 1- and 3.5 +/- 0.6-fold increases), but had no effect on side-chain cleavage cytochrome P450 or cytochrome P450 aromatase mRNAs. 3beta-Hydroxysteroid dehydrogenase mRNA levels were increased (3.1 +/- 1.3-fold increase) by activin A, but not by inhibin A. However, inhibin A blocked the stimulatory action of activin A. In keeping with these changes in the steroidogenic enzyme mRNAs, both peptides enhanced the conversion of exogenous 22R-hydroxycholesterol and progesterone, but only activin A increased the conversion of dehydroepiandrosterone into testosterone. In conclusion, our findings demonstrate that both inhibin A and activin A have a stimulatory effect on immature porcine Leydig cell differentiated function in vitro. As inhibin has a stimulatory and activin has an inhibitory effect on rat Leydig cell function in vitro, the effects of these factors on Leydig cells seem to be species dependent.
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PMID:Stimulating effect of both human recombinant inhibin A and activin A on immature porcine Leydig cell functions in vitro. 934 6

The distinct gender-specific patterns of fat distribution in men and women (android and gynoid) suggest a role for sex steroids. In keeping with these observations, it has been suggested that estrogens can promote preadipocyte cell proliferation and/or differentiation. The enzyme aromatase P450 is responsible for the conversion of androgen precursor steroids to estrogens and may, therefore, have a role in regulating adipose tissue mass and its distribution. We have investigated the glucocorticoid regulation of aromatase expression in human adipose tissue, specifically to define any site- and gender-specific differences. Abdominal subcutaneous (Sc) and omental (Om) adipose tissue was obtained from male and female patients undergoing elective surgery. After collagenase digestion, preadipocytes were cultured in serum-free medium, for 6-10 d, until confluent with either cortisol (10(-6) M, 10(-7) M) or insulin (500 nM) or a combination of both treatments. Adipocytes were studied in suspension cultures. Aromatase activity was assessed using tritiated [1 beta-(3)H]-androstenedione as substrate. In Sc preadipocytes, basal aromatase activity increased in females from 11.5 +/- 1.4 (mean plus minus SEM) to 28.0 +/- 1.8 pmol/mg x h (n = 17, P < 0.05) with 10(-6) M cortisol. By contrast, in males, aromatase activity was inhibited by 10(-6) M cortisol (19.4 +/- 2.4 pmol/mg x h vs. 7.5 +/- 1.3, n = 9, P < 0.01; men vs. women, P < 0.005). These data were endorsed through Western blot analysis using an in-house antihuman aromatase antibody, which recognized a specific 55-kDa species. Aromatase activity was less at Om sites in preadipocytes, increasing in females from 1.1 +/- 0.2 to 3.2 +/- 0.7 pmol/mg x h with 10(-6) M cortisol (P < 0.05) and in males from 2.6 +/- 0.1 pmol/mg x h to 7.8 +/- 0.3 pmol/mg x h after cortisol (men vs. women, P < 0.001). Cortisol-induced aromatase activity in Om adipocytes from postmenopausal females was higher than that in premenopausal females (P < 0.001). Insulin had no independent effect on aromatase expression, but coincubation of preadipocytes with cortisol and insulin eliminated both gender- and site-specific differences. In conclusion, in women, but not men, cortisol increased aromatase activity at Sc sites, and this may facilitate predilection for Sc adiposity in females. The observed site-, gender-, and menopausal-specific differences in the glucocorticoid regulation of this enzyme may contribute to the gender- and menopausal-specific patterns of fat distribution.
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PMID:Glucocorticoid regulation of p450 aromatase activity in human adipose tissue: gender and site differences. 1188 5