Metabolism of steroid hormones in vitro by follicular tissues of the Japanese quail

The cell-free homogenates of the theca layers and granulosa layers of quail follicles were incubated at 39 degrees C with 14C-labeled steroids in the presence of NADPH. At the end of incubation, radioactive steroids were extracted and analyzed by thin-layer chromatography. When radioactive progesterone was employed as the substrate, 17 alpha-hydroxyprogesterone and androstenedione were obtained as the metabolites. 17 alpha-Hydroxylase activity, estimated from the amounts of these two metabolites, was high in the theca layers of the second largest (F2) and the third largest (F3) follicles. The theca layer of the largest follicle (F1) and the granulosa layers of all three follicles were essentially devoid of this enzyme activity. The activity of C17-20 lyase was estimated from the amount of androstenedione that was obtained as a sole metabolite in the incubation of radioactive 17 alpha-hydroxyprogesterone. This enzyme showed a tissue distribution similar to 17 alpha-hydroxylase. When radioactive androstenedione was used as the substrate, testosterone, 5 beta-androstane-3,17-dione, and 3 beta-hydroxy-5 beta-androstan-17-one were identified as the metabolites. 17 beta-Hydroxysteroid dehydrogenase activity, estimated from the amount of testosterone, was higher in the granulosa layers than in the theca layers. On the other hand, 5 beta-reductase activity, estimated from the sum of 5 beta-androstane-3,17-dione and 3 beta-hydroxy-5 beta-androstan-17-one, was almost equally distributed in the two layers. In order to investigate the changes in the enzyme activities during the ovulatory cycle, birds were killed at various times before the predicted ovulation of F1. When the 17 alpha-hydroxylase activity was estimated in the cell-free homogenates of the theca layers, peaks in the activity were observed 32, 42, 54, and 66 h before ovulation of F1. There was a small peak 18 h before ovulation, and activity then started to decrease. The change of C17-20 lyase activity during the cycle was completely parallel with that of 17 alpha-hydroxylase activity.     

Influence of neonatal steroid (diethylstilbestrol, allylestrenol) treatment on the sexual behaviour of the adult rat

A single neonatal treatment with diethylstilbestrol (DES) or allylestrenol (AE) considerably depressed the sexual activity of male rats in adulthood. DES had a stronger depressive effect than AE. Though the adult sexual activity of intact female rats was also reduced by DES it was not influenced by AE. Ovariectomized females that had been hormone-treated before experimental mating showed reduced sexual activity under the influence of neonatal DES-treatment but increased sexual activity when treated neonatally with AE.     

Binary assessment of early approach-behaviour in the Japanese quail.

Visually-elicited early approach-behaviour was studied in 1013 Japanese quail chicks (Coturnix coturnix japonica) by a newly developed, binary assessment procedure. This procedure was shown to be highly effective for identifying approach preferences and related indivisual differences in early approach-behaviour. Experimental results show that quail chicks exhibit approach-responses to a flashing light. Within various paired intensity-combinations of the tested intensity-range of approximately two log units, they consistently preferred the higher intensity stimulus.     

Inhibition of 17beta-hydroxysteroid dehydrogenases by phytoestrogens: comparison with other steroid metabolizing enzymes

Effects of phytoestrogens on human health have been reported for decades. These include not only beneficial action in cancer prevention but also endocrine disruption in males. Since then many molecular mechanisms underlying these effects have been identified. Targets of phytoestrogens comprise steroid receptors, steroid metabolising enzymes, elements of signal transduction and apoptosis pathways, and even the DNA processing machinery. Understanding the specific versus pleiotropic effects of selected phytoestrogens will be crucial for their biomedical application. This review will concentrate on the influence of phytoestrogens on 17beta-hydroxysteroid dehydrogenases from a comparative perspective with other steroid metabolizing enzymes.     

Subcellular fractionation of rainbow trout gonads with emphasis on microsomal enzymes involved in steroid metabolism

Summary Rainbow trout gonads were subfractionated by differential centrifugation with emphasis on obtaining preparations suitable for the study of steroid-metabolizing enzymes. A fractionation scheme was evaluated for the mature testis and for 3 ovarian developmental stages. The distribution of cell organelles among the fractions was determined using enzyme-markers and electron microscopy. The fractionation scheme was found to be suitable for separating mitochondria and microsomes which were recovered at similar yields to those that had been reported for other extraheptic fish tissues. Fractionation of the mature ovary was fraught with problems probably because a large yolk protein cytosole fraction interfered with the recovery of microsomes. However, no difference in the specific activity of microsomal NADPH-cytochrome c-reductase between the various organ preparations was evident. The testis microsomes contained detectable amounts of cytochrome P450, whereas its content in the various ovary microsomes was too low to be detected. Progesterone 17-hydroxylase was detected in microsomes from testes and early developing ovaries, and microsomal aromatase activity was present in microsomes from early developing, mature and postovulatory ovaries. Furthermore, the testis microsomes contained a highly active UDP glucuronosyltransferase with testosterone used as a substrate.     

The role of the fetal gonads and placenta in steroid production, maintenance of pregnancy and parturition in the mare.

The effects of fetal gonadectomy on steroid production and the maintenance of pregnancy in the mare were studied. Removal of the fetal gonads resulted in an immediate fall in maternal plasma concentrations of conjugated and unconjugated oestrogens whereas progestagen levels remained unchanged. Hormone profiles in mares carrying sham-operated fetuses remained similar to those in unoperated control mares. Plasma levels of 13,14-dihydro-15-oxo-PGF-2 alpha (PGFM) were much lower, and uterine contractions weaker, during labour in mares carrying gonadectomized foals than in control mares. Pregnancy was maintained until parturition at term in the mares carrying gonadectomized fetuses. However, 3 of the 4 gonadectomized foals were dysmature and died during or soon after birth. The biosynthetic pathways involved in the production of oestrogens by the feto-placental unit and the possible role of oestrogens in fetal development in the pregnant mare are discussed.     

Reactivity of the epithelial cells of the bovine oviduct in vitro on the exogenic gonadotropic and steroid hormones. Part I: The effect of gonadotropic and steroid hormones on the amount of lipids and activity of dehydrogenases.

Effects of 17 beta-estradiol, testosterone, progesterone, luteinizing hormone and a combined effect of estradiol and progesterone on the epithelial cells of the bovine oviduct cultured in vitro were investigated. It was found that these cells may transform under the effect of hormones. The effect of the applied hormones on the amount of lipids and activity of the dehydrogenases delta 5 3 beta-OH-SDH and G6P-DH was evident. Cells in vitro most intensely reacted on testosterone and estradiol: these hormones caused an increase of lipids and of enzymatic activity. The cells also reacted to progesterone and the luteinizing hormone which in turn decreased both activity and accumulation of lipids in cells.