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Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Monolayer cultures of mouse adrenal tumor cell line Y-1 have been used to investigate the effects of glucocorticoid on cell replication, [3H]thymidine incorporation into the trichloroacetic acid-precipitated cell fraction, steroidogenesis, and the ACTH receptors of adrenocortical cells. Corticosterone at a concentration of 5.0--50 micrograms/ml inhibited cell replication and [3H]thymidine incorporation into trichloroacetic acid-precipitated cell fraction in a dose-related manner. Corticosterone at a concentration of 0.5--50 micrograms/ml inhibited ACTH-induced steroidogenesis in a dose-related manner. Steroids which do not possess glucocorticoid action did not show such inhibitory effects on cell replication and steroidogenesis of Y-1 cells. The characteristics of the ACTH receptors of these cells remained unaffected by corticosterone. Our findings suggest that synthesized or secreted glucocorticoid may play an important role in the direct regulation of proliferation and function of adrenocortical cells under physiological conditions.
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PMID:Inhibitory effects of corticosterone on cell proliferation and steroidogenesis in the mouse adrenal tumor cell line Y-1. 22 Nov 80

The effects of a number of steroids on the conversion of progesterone to 5alpha-dihydroprogesterone by hypothalamic and pituitary progesterone 5alpha-reductase have been investigated. Using enzyme preparations from female rats and 3H-progesterone as substrate, 5alpha-reduced products (5alpha-dihydroprogesterone and 3alpha-hydroxy-5alpha-pregnan-20-one) were analyzed by reverse isotopic dilution analysis. The amount of total 5alpha-reduced products formed was compared in the presence and absence of the test steroid. Derivatives lacking the delta4 and/or the 3-keto moiety were without effect. Corticosterone had no effect. 16beta-Methylprogesterone inhibited progesterone 5alpha-reduction in both tissues by at least 65%, while the 2alpha-, 6alpha-, and 7alpha-methylated derivatives had lesser effects. 3-Oxo-4-pregnene-20beta-carboxaldehyde and 21-fluoroprogesterone were potent inhibitors. 17-Hydroxyprogesterone was a competitive inhibitor (substrate) with Ki's of 0.27 micrometer (pituitary) and 0.29 micrometer (hypothalamus). Medroxyprogesterone exerted little inhibitory effect. Of the 19-nor-steroids examined, only norethindrone appreciably inhibited the 5alpha-reduction. These results suggest that some natural delta4-3-ketosteroids can modify enzymatic activity. Also, inhibitory analogues may be useful for studies on the role of this 5alpha-reduction of progesterone.
Steroids 1978 Jun
PMID:The effect of progesterone analogues, naturally occurring steroids, and contraceptive progestins on hypothalamic and anterior pituitary delta4-steroid (progesterone) 5alpha-reductase. 69 71

An analysis of 168 plasma samples from intact rats, one to 35 days of age, was performed using both brief and specific fluorometric procedures. The amount of fluorescence produced by the brief procedure which could be attributed to corticosterone ranged from a maximum of 72% to a minimum of 16% of the total fluorescence value. Corticosterone represented 50% or more of the brief assay value in only five out of 18 groups of animals assayed. Following statistical analysis of the nonspecific fluorescence, a significant variation was found due to the age of the animal. A highly significant increase in nonspecific fluorescence was found in 21-day old animals following histamine injection. It was concluded that the brief fluorometric assays for corticosterone were of little value if specificity was desired.
Steroids 1978 Dec
PMID:The fluorometric assay of rat plasma corticosterone: evaluation of nonspecific fluorescence. 73 95

The effect of endogenous corticosterone on the quantitative measurement of dexamethasone receptors in liver cytosols from developing rats has been studied. Liver cytosols from adrenalectomized rats were preincubated with increasing concentrations of nonlabeled corticosterone and the levels of detectable dexamethasone receptors were subsequently determined either directly or after removal of unbound corticosterone. Corticosterone concentrations of 50 nM or lower had no significant effect on the specific binding of labeled dexamethasone. Higher concentrations of corticosterone resulted in under-estimation of dexamethasone receptor levels. The mean levels of endogenous corticosterone in liver cytosols from 19.5- to 21.5- day fetuses, 22-day fetuses, 6-day-old immature rats and adult rats were 27.40, 11.91, 0.81 and 4.05 nM, respectively. It is concluded that variations in the levels of circulating corticosterone in the rat under normal physiological conditions have no significant effect on the quantitative measurement of total (occupied and unoccupied) receptor sites for dexamethasone in liver cytosol. This is supported by the finding that prior treatment of liver cytosols, from rats at different stages of development, with charcoal to remove unbound steroids has no effect on the amount of detectable dexamethasone receptors.
Steroids 1976 Jul
PMID:Effect of endogenous corticosterone on the determination of dexamethasone receptor levels in rat liver cytosol. 96 Jan 47

Steroids (testosterone, oestrogen, progesterone, corticosterone, dexamethasone and deoxycorticosterone) were administered intramuscularly (0.1 mg.100 g bw-1) on seven consecutive days to juvenile male soft-shelled turtles. Serotonin, norepinephrine and epinephrine contents of the pineal-paraphyseal complex were measured spectrofluorometrically 24 h after the last injection. Testosterone and oestrogen decreased serotonin, norepinephrine and epinephrine levels. Progesterone treatment resulted in an increase of serotonin level and a fall in norepinephrine and epinephrine levels. Corticosterone treatment caused an increase of serotonin level and a decrease of norepinephrine and epinephrine levels. Dexamethasone failed to alter serotonin content, increased norepinephrine and decreased epinephrine levels. Deoxycorticosterone decreased serotonin and elevated epinephrine content.
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PMID:Effect of steroid hormones on serotonin, norepinephrine and epinephrine contents in the pineal-paraphyseal complex of the soft-shelled turtle (Lissemys punctata punctata). 143 Apr 21

Two strains of spontaneously hypertensive rats (SHRs) differ in their susceptibility to the hypertensive effects of dietary NaCl. One strain exhibits a significant elevation of blood pressure after dietary NaCl loading (SHR-S), whereas the other does not (SHR-R). Since differences in adrenocortical steroid production may contribute to NaCl sensitivity, we compared 19-nordeoxycorticosterone (DOC), 18-OH-DOC, aldosterone, and corticosterone excretion in 6-week-old male rats from the SHR-S (n = 24) and SHR-R (n = 24) strains. The rats were housed in metabolic cages (two rats per cage) and given either basal (1%) or high (8%) NaCl diet. Urinary steroids were analyzed using thin-layer chromatography and radioimmunoassay methods. The high NaCl diet elevated the urinary excretion of the four corticosteroids in both rat strains. 19-nor-DOC decreased with time in both the SHR-S and SHR-R strains, and was not different between strains on either diet. Aldosterone was increased in the SHR-S strain compared with the SHR-R strain on the low NaCl diet, but aldosterone was not different between the two strains on the high NaCl diet. Corticosterone and 18-OH-DOC did not differ between strains. These data confirm that 19-nor-DOC is higher in young prehypertensive SHRs and decreases with age. Aldosterone excretion is higher in the SHR-S strain compared with the SHR-R strain on the low NaCl diet.(ABSTRACT TRUNCATED AT 250 WORDS)
Steroids 1992 Feb
PMID:Adrenocorticosteroid excretion in salt-sensitive and salt-resistant spontaneously hypertensive rats. 162 Dec 63

Steroids have fast and probably partly GABA-mediated central anaesthetic effects for which a strict structure-function correlation is required. They also affect short- and long-term activity in the CNS in other ways. One of these is long-term potentiation (the persistent facilitation of synaptic transmission), which occurs particularly in the hippocampus after repetitive stimulation of a fibre pathway. Two clearly distinguished components of the evoked response can be studied in the hippocampus: the excitatory postsynaptic potential (EPSP) which denotes the graded depolarization of the somadendritic region of the neuron and the population spike (PS), a manifestation of the all-or-none discharge of the cell action potential. Corticosterone had a significant depressant effect on the EPSP component of the evoked response immediately and 15 min after injection. Thereafter EPSP amplitudes were within normal values. Corticosterone significantly decreased the PS immediately after the train, the component remaining low 30 min after the train. 5 alpha-Dihydrocorticosterone (a ring A-reduced metabolite of corticosterone) significantly reduced the PS component of the response at all times after injection. 18-Hydroxydeoxycorticosterone and deoxycorticosterone significantly decreased both EPSP and PS components of the evoked response from the time of infusion. Contrary to expectation, tetrahydrodeoxycorticosterone was ineffective in decreasing, and if anything, enhanced the development of long-term potentiation. 18-Hydroxydeoxycorticosterone 21-acetate behaved like vehicle, except for the first 30 min after injection, when the EPSP was decreased. Different steroids can selectively affect different parts of a neuron and appear to show a different structure-function correlation for long-term potentiation from that required for anaesthesia.
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PMID:Early and late effects of steroid hormones on the central nervous system. 196 99

Steroids may rapidly alter neuronal function and behavior through poorly characterized, direct actions on neuronal membranes. The membrane-bound receptors mediating these behavioral responses have not been identified. [3H]Corticosterone labels a population of specific, high-affinity recognition sites (dissociation constant = 0.51 nanomolar) in synaptic membranes from an amphibian brain. These binding sites were localized by receptor autoradiography in the neuropil, outside the regions of perikarya. The affinities of corticoids for this [3H]corticosterone binding site were linearly related to their potencies in rapidly suppressing male reproductive behavior. Thus, it appears that brain membranes contain a corticosteroid receptor that could participate in the regulation of behavior.
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PMID:A corticosteroid receptor in neuronal membranes. 206 98

Using cultured Y-1 mouse adrenal tumor cells which produce 20 alpha-hydroxy-4-pregnen-3-one (20-DHP), it was found that 0.01 mM corticosterone and deoxycorticosterone increased basal and inhibited ACTH-induced 20-DHP production during consecutive 30 and 120 min incubations. Steroid effects were concentration-dependent and reversible. Six other steroids tested did not stimulate 20-DHP production and varied in ability to inhibit ACTH-stimulated steroidogenesis. Experiments demonstrated that 20-DHP production following treatment with cholera toxin, N,0'-dibutyryl cyclic AMP (dbcAMP), or pregnenolone was not inhibited by exogenous steroids. Corticosterone (0.01 mM) increased basal and inhibited ACTH-induced intracellular cyclic AMP (cAMP) production. Cytochalasin D, a microfilament perturbing agent, inhibited steroid-stimulated 20-DHP production, suggesting that ACTH and steroid stimulation mechanisms were similar. These findings taken together suggest that exogenous steroids can alter steroidogenesis by modifying plasma membrane adenylate cyclase activity.
Steroids 1985 Jul
PMID:Exogenous steroids alter steroidogenesis in cultured Y-1 adrenal tumor cells by actions preceding cyclic AMP. 301 50

Corticosterone-and progesterone-binding activity were measured by saturation analysis, with dextran-charcoal separation, in plasma obtained from male and female rats, and a normal male and female human. In plasma from normal male and female rats, progesterone was much less effective than corticosterone in displacing 3H-corticosterone from plasma protein binding sites although the parallelism of the displacement curves indicated competition for the same binding sites. In plasma from the normal male human, corticosterone and progesterone were equally effective in displacing 3H-corticosterone. However, 3H-progesterone showed no apparent binding to either rat or human plasma proteins, suggesting that dextran-charcoal effectively removed progesterone from transcortin binding sites at 4 degrees C. This observation was confirmed by multiple equilibrium dialysis. In dialysis, 3H-corticosterone and 3H-progesterone were bound equally by human plasma, but rat plasma bound 3H-corticosterone to a much greater extent than it did 3H-progesterone. These data indicate that, in contrast to human plasma, rat plasma has much greater affinity for corticosterone than for progesterone.
Steroids 1980 Sep
PMID:Comparison of plasma corticosterone- and progesterone-binding activity in rat and human. 700 80


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