Showing papers on "Steroid biosynthesis published in 1980"

Steroid Biosynthesis by Isolated Human Ovarian Follicular Cells in Vitro

Abstract: Cultured thecal preparations from human ovarianfollicles obtained from patients during the follicular phase ofthe menstrual cycle produced large amounts of Δ4-androstenedioneand smaller amounts of testosterone and other androgenswhen stimulated by hCG, (Bu)2cAMP, and prostaglandin E2, butnot when stimulated by FSH. Prostaglandin E2 also stimulatedthecal cAMP production under the same conditions. By contrast,androgen production by granulosa cells was negligible with orwithout gonadotropins in the culture medium. Granulosa cellsalso did not produce 17β-estradiol, even when exposed to FSHand hCG, unless supplied with exogenous Δ4-androstenedione.On the other hand, thecal preparations did not produce significantamounts of 17β-estradiol even in the presence of FSH, hCG,and relatively large amounts of exogenous Δ4-androstenedione.These observations suggest that Δ4-androstenedione producedby LH or hCG-stimulated thecal cells is the main substrate forthe synthesis of 17β-estradiol by FSH-stimulated granulosa cell...

Relaxin Production by the Porcine Ovarian Graafian Follicle in vitro

Abstract: Immunoreactive rela.xin was shown to be present in pools of porcine follicular fluid collected from individual ovaries from cyclic and pregnant sows. In the cyclic animals, the highest relaxin level was obtained from ovaries containing active corpora lutes, but at no stage during the cycle did relaxin content of follicular fluid approach that found in ovaries of pregnant sows. Fractionation of follicular fluid on Sephadex C-SO revealed at least three immunoreactive relaxin peaks of differing molecular weight: >40,000, 20,000, and one corresponding to authentic relaxin (6300). Serum of pregnant sows when fractionated in a similar fashion contained more of the highest molecular weight immunoreactive relaxin while only ‘\‘20% of the immunoreactivity was associated with 6300 relaxin. Isolated ovarian follicles and follicular tissue released relaxin throughout prolonged periods in culture. Relaxin output in vitro was significantly higher for tissue obtained from pregnant than from nonpregnant sows. Examination of the relationship between steroid hormone and relaxin release revealed that follicle wall segments, washed free of follicular fluid, released both more relaxin and steroids than did intact follicles. Of the steroids examined, the pattern of relaxin most resembled that found for progesterone, which showed an increase after 48 h of culture as the tissue underwent spontaneous luteinization. The relationship between steroid hormone and relaxin biosynthesis was further studied in these cultures by the addition of inhibitors of steroid biosynthesis. Aminoglutethimide effectively reduced production of all steroids studied without significantly reducing the total production of relaxin over the culture period. Tniostane and androstriene 3, 17-dione were only partially effective in reducing steroidogenesis but caused a significant reduction in total relaxin production. Follicular tissue therefore synthesizes and secretes relaxin in vitro, but the cellular origin, the relationship with steroidogenesis, and the routes of release remain to be established.

Impaired cortisol secretion in abetalipoproteinemia.

Abstract: In the adrenal gland cholesterol for steroid biosynthesis is derived from both de novo biosynthesis and receptor mediated uptake of plasma low density lipoproteins (LDL) In the present study we have compared ACTH stimulated adrenal production of cortisol in four control subjects and one adult male patient with abetalipoproteinemia, a disorder in which LDL is absent Basal morning cortisol levels in the plasma in the control subjects (133 +/- 16 microgram/dl) and abetalipoproteinemic patient (146 micrograms/dl) were similar During infusion of alpha 1, 24 ACTH however, plasma cortisol levels were higher in the control subjects than in the abetalipoproteinemic patient and this difference was significant at times after 4 hours Urinary excretion of both 17-hydroxy and 17-ketosteroids over the 24 hour infusion period was also significantly lower in the abetalipoproteinemia patient indicating that cortisol production rates were reduced Our results suggest that in the absence of plasma low density lipoproteins, as occurs in abetalipoproteinemia, the maximal production of adrenal corticosteroids is impaired By inference, these findings lend in vivo support to the view that plasma low density lipoproteins serve as an important source of cholesterol for adrenal steroidogenesis in man

Steroid biosynthesis in the gonads of the teleost fish Jenynsia lineata

Abstract: 1. 1. A series of enzyme systems for steroid biosynthesis in the ovary and testis of Jenynsia lineata were demonstrated in vitro . In the ovary and testis of this teleost the following enzymic conversions of radiolabelled steroid substrates were observed in vitro : Pregnenolone → 17α-hydroxypregnenolone plus androstenedione and testosterone and Pregnenolone → 17α-hydroxyprogesterone plus androstenedione and testosterone. 2. 2. In addition, an unusual finding in the ovary and testes was the biosynthesis of 11-deoxycortisol (compound S) from the pregnenolone and progesterone substrates and the 21-hydroxylation of progesterone to form 11-deoxycorticosterone (DOC). 3. 3. The male gonad also exhibited 11β-hydroxylase activity and testosterone was converted to 11β-hydroxyandrostenedione. 4. 4. All conversions of radiolabelled substrates were identified on the basis of reverse isotope dilution and crystallization to constant specific activity. 5. 5. The physiological significance of DOC and 11β-hydroxyandrostenedione biosynthesis in the gonads of Jenynsia lineata and its possible role in the reproductive process are viewed against similar findings in other fishes.

Effect of Clomiphene Citrate on Testicular Steroid Metabolism in Man

Abstract: Administration of clomiphene citrate to males with normal peripheral testosterone levels increased the serum levels of FSH, LH, testosterone and low polar oestrogens and also the urinary excretion of LH, low polar oestrogens, dehydroepiandrosterone, androsterone and aetiocholanolone. No significant change was noted for the urinary excretion of 17-oxogenic steroids. Addition of clomiphene citrate (10(-4) to 2 X 10(-3) M) to incubations of [7-3H, 21-14C] progesterone with human testicular biopsy specimens in vitro caused a slight inhibition in the formation of 17 alpha-hydroxyprogesterone and a slightly increased formation of 20 alpha-hydroxy-4-pregnen-3-one but no measurable changes in the C19 steroid formation. The results support the hypothesis that there is selective action of clomiphene citrate upon the adrenal C19 steroid biosynthesis in the human male, combined with an indirect effect upon the testes via the hypothalamic-pituitary system. A direct effect on the gonadal steroidogenesis can, however, not be ruled out.

Chirugie des glandes surrenales

Abstract: The adrenal cortex and the adrenal medulla functionally quite distinct, are discussed separately. Knowledge of the steroid biosynthesis with its three productive pathways (glycocorticoids, mineralcorticoids and sex hormones) is essential not only to understand the physiopathology of the adrenal cortex, but also to delineate the necessary diagnostic hormonal screening tests and the applied treatment modalities. When surgery is indicated, a precise preoperative evaluation of the patient is essential with correction of all possible anomalies. With this all in mind, the Cushing syndrome, the adrenogenital syndrome and the primary aldosteronism (Conn) are discussed with regard to etiology and treatment. Patients who underwent a bilateral adrenalectomy are likely to live a normal life as long as the hormonal substitution therapy (glycocorticoids and mineralocorticoids) is adequate. When stress situations, such as surgery, do occur, adjustments of this therapy are essential. The pathology of the adrenal medulla confronts us with the problems of pheochromocytoma. An adequate preoperative preparation of the patients with adrenergic blocking agents and fluid support allows for a surgical intervention with a low morbidity and mortality. In conclusion surgery of the adrenals requires a perfect knowledge of the associated physiopathology and a close cooperation between the endocrinologist, the surgeon and the anesthesiologist.

Ultrastructural Characteristics of Adult Rat Adrenocortical Cells Maintained in vitro With and Without ACTH

Abstract: Bhattacharyya, T. K., Butler, D. G., Price, C. S. 1980. Ultrastructural characteristics of adult rat adrenocortical cells maintained in vitro with and without ACTH. (Ramsay Wright Zoological Laboratories, Department of Zoology, University of Toronto, and Division of Endocrinology, Toronto Western Hospital, and Department of Medicine, University of Toronto, Canada.) — Acta zool. (Stockh.) 61(1): 9–21. The ultrastructural morphology of adrenocortical cells of adult rats maintained in culture for four days with and without corticotropin (ACTH) was studied in comparison to freshly dissociated cells. Identification of cells belonging to zona glomerulosa, zona fasciculata, and zona reticularis was made on the characteristics of the mitochondria and smooth endoplasmic reticulum (SER), and was confirmed by comparison with cellular layers from intact adrenals. Without ACTH, glomerulosa and fasciculata cells showed disappearance of SER, atrophied Golgi apparatus (GA), and a striking proliferation of granular reticulum. Fascicular cells had a loss in mitochondrial matrix density and the mitochondrial cristae showed a tendency to convert to lamellar glomerulosa-type cristae. Zona reticularis cells were not strikingly altered. Maintenance with ACTH led to increased cell size and islet formation of cortical cells. Glomerulosa cells had normal appearance and fasciculata cells manifested a pronounced development of GA and SER, and a normal configuration of mitochondria. The effects of ACTH on glomerulosa cells suggest a trophic influence of ACTH on these cells in vitro. The alterations observed in fascicular cell mitochondria and SER can be explained in terms of known concepts of steroid biosynthesis and basically agree with the patterns of steroid synthesis observed in these cells previously (Price et al. 1975).