RESUMEN
Prior to this work, we found that adrenal as well as extra-adrenal factors activate the response of renal 11beta-hydroxysteroid dehydrogenase 2 to stressful situations. These results -showing ways through which the organism hinders the pathological occupation of mineralocorticoid receptors by glucocorticoids leading to sodium retention and hypertension- prompted the present study on the nature of the above-mentioned extra-adrenal factors. Serotonin was chosen because of its properties as a widely distributed neurohormone, known to interact with glucocorticoids at many sites, also exhibiting increased levels and effects under stressful situations. We studied serotonin effects on 11beta-hydroxysteroiddehydrogenase 2 activity in a cell line derived from distal nephronpolarized-epithelium, employing 3H-corticosterone as substrate. The end-product, 3H- 11 -dehydrocorticosterone was separated from the substrate by HPLC and quantified. Serotonin stimulated 1I beta-hydroxysteroiddehydrogenase 2 activity only at 2nM and 25pM, the magnitude of the responsedepending also on substrate concentration. The stimulation was blocked by thespecific inhibitors methiothepin and ketanserin. We postulate that the organism partially prevents renal mineralocorticoid receptor occupancy by glucocorticoids, circulating at enhanced levels under stressful situations, through serotonin-mediated catabolic regulation of the 11beta-hydroxysteroid dehydrogenase 2 activity. Given many, mostly positive, interactions between both hormones, this might eventually pave the way to studies on a new regulatory axis.(AU)
Asunto(s)
Animales , Perros , 11-beta-Hidroxiesteroide Deshidrogenasa de Tipo 2/metabolismo , Corticosterona/análogos & derivados , Corticosterona/metabolismo , Activación Enzimática/efectos de los fármacos , Serotonina/farmacología , Línea Celular , Nefronas/enzimología , Comunicación ParacrinaRESUMEN
Corticosterone (B) and a less polar form or derivative of 18-hydroxycorticosterone obtained by dissolving the mother-steroid in 0.01 N HCl, (L), were assayed as precursors to aldosterone in: 1) samples only containing buffer (C); 2) samples containing buffer and boiled adrenal tissue (phi); 3) samples containing surviving quartered rat adrenals (G). The yields of aldosterone from B were the following: 1.24
in sample (C); 0.21
in sample pHI; and 5.03
in sample (G). The yields of aldosterone from L were the following: 2.66
in sample (C); 2.30
in sample (phi) ; and 2.47
in sample (G). A factor inhibiting the conversion of B, but not of L, to aldosterone was present in samples containing boiled tissue.
RESUMEN
Corticosterone (B) and a less polar form or derivative of 18-hydroxycorticosterone obtained by dissolving the mother-steroid in 0.01 N HCl, (L), were assayed as precursors to aldosterone in: 1) samples only containing buffer (C); 2) samples containing buffer and boiled adrenal tissue (phi); 3) samples containing surviving quartered rat adrenals (G). The yields of aldosterone from B were the following: 1.24
in sample pHI; and 5.03
in sample (G). The yields of aldosterone from L were the following: 2.66
in sample (phi) ; and 2.47
in sample (G). A factor inhibiting the conversion of B, but not of L, to aldosterone was present in samples containing boiled tissue.
RESUMEN
The effect [quot ]in vivo[quot ] of 11 beta-hydroxy-pregna-1,4-diene-3,20-dione (delta HOP) in acute and chronic treatment was studied in mice compared to those treated with dexamethasone and vehicle. In acute experiments an injection of 2 mg/100 g body weight of delta HOP had a maximal inhibitory effect in 3H-uridine incorporation by thymocytes 18 h after the injection, disappearing 36 h later, meanwhile no change was observed in plasma corticosterone levels at any time. The dose 0.033 mg/100 g body weight of dexamethasone produced a high inhibition 5 h after the injection, and a significant decrease in plasma corticosterone was produced at this time; the effect disappeared at 24 h. In the chronic treatment delta HOP produced the maximal inhibition 5 h after the treatment; this effect was maintained until 36 h and disappeared at 48 h without change in corticosterone levels. Meanwhile dexamethasone produced the same inhibition as delta HOP 5 h after the treatment; this effect disappeared after 18 h. In those animals plasma corticosterone decreased during longer time than in acute treatment, since it continued lower than normal at 18 h and it recovered at 24 h. After 5 h of a chronic treatment delta HOP did not change thymus and spleen weights, but they decreased with dexamethasone treatment. These results suggest that the [quot ]in vivo[quot ] actions of delta HOP is different from that of glucocorticoids.
RESUMEN
A high-pressure-liquid-chromatography (HPLC), isotope dilution method for the determination of corticosterone in rat plasma is reported. Main characteristics of the technique are: efficient separation of the steroid from 18-HO-DOC and 11-deoxycortisol; two easy pre-purification steps consisting of an acetone extraction-deproteinization and fractionation on Sephadex LH-20; a sensitivity of 5 ng per injection and the possibility of determining 25 ng corticosterone in approximately one milliliter rat plasma.
RESUMEN
In steroidogenic tissues of the developing hen, specially in the right ovary, 5 beta reductase (Rase) increases after hatching. delta aminolevulinic acid synthetase (ALAs) in these tissues is more active than hepatic ALAs during most embryonic stages. But after hatching, only hepatic and adrenal ALAs increase sharply; ALAs increases only moderately in the left ovary and descends to very low values in the right one. A relationship between ALAs and Rase curves during embryonic development of the left ovary and the adrenal suggests that 5 beta pregnanedione is a natural inducer of ALAs in these functional endocrine glands, at least during their embryonic stages.
RESUMEN
A method based on the indophenol reaction for the determination of ammonium ions in small urine samples from research animals is described. The method is precise and specific. Sensitivity (epsilon 630 molar = 174 X 10(3)) is far beyond needs. Interference by blood in hematuric samples can be avoided.
RESUMEN
In acute experiments, aldosterone (aldo), 18-hydroxycorticosterone (18 OH B) or corticosterone (B) were administered to adrenalectomized rats and parameters related to acid-base balance measured in urine samples collected for 3.5 hours after injection. Aldo reduced sodium excretion but did not affect pH nor the outputs of K, NH4+, CO3H-, phosphates nor titratable acidity. 18 OH B increased the excretion of titratable acidity and reduced drastically that of CO3H-. The lowest effective dose (3 micrograms) promoted Na excretion while the highest dose employed (6 micrograms) reduced pH and Na excretion. B increased the excretions of phosphates and ammonium, the former drastically. Potassium output either increased or did not change, and pH augmented marginally. It is postulated that a) 18 OH B is a naturally occurring steroid eliciting urine-acidification not necessarily accompanied by sodium retention; and b) at least B and 18 OH B in the rat, possess hormonal roles according to which the latter promotes the presence of protons, and the former, that of acute proton-acceptors in the lumen of tubuli.
RESUMEN
A method based on the indophenol reaction for the determination of ammonium ions in small urine samples from research animals is described. The method is precise and specific. Sensitivity (epsilon 630 molar = 174 X 10(3)) is far beyond needs. Interference by blood in hematuric samples can be avoided.
RESUMEN
In acute experiments, aldosterone (aldo), 18-hydroxycorticosterone (18 OH B) or corticosterone (B) were administered to adrenalectomized rats and parameters related to acid-base balance measured in urine samples collected for 3.5 hours after injection. Aldo reduced sodium excretion but did not affect pH nor the outputs of K, NH4+, CO3H-, phosphates nor titratable acidity. 18 OH B increased the excretion of titratable acidity and reduced drastically that of CO3H-. The lowest effective dose (3 micrograms) promoted Na excretion while the highest dose employed (6 micrograms) reduced pH and Na excretion. B increased the excretions of phosphates and ammonium, the former drastically. Potassium output either increased or did not change, and pH augmented marginally. It is postulated that a) 18 OH B is a naturally occurring steroid eliciting urine-acidification not necessarily accompanied by sodium retention; and b) at least B and 18 OH B in the rat, possess hormonal roles according to which the latter promotes the presence of protons, and the former, that of acute proton-acceptors in the lumen of tubuli.
RESUMEN
The effect [quot ]in vivo[quot ] of 11 beta-hydroxy-pregna-1,4-diene-3,20-dione (delta HOP) in acute and chronic treatment was studied in mice compared to those treated with dexamethasone and vehicle. In acute experiments an injection of 2 mg/100 g body weight of delta HOP had a maximal inhibitory effect in 3H-uridine incorporation by thymocytes 18 h after the injection, disappearing 36 h later, meanwhile no change was observed in plasma corticosterone levels at any time. The dose 0.033 mg/100 g body weight of dexamethasone produced a high inhibition 5 h after the injection, and a significant decrease in plasma corticosterone was produced at this time; the effect disappeared at 24 h. In the chronic treatment delta HOP produced the maximal inhibition 5 h after the treatment; this effect was maintained until 36 h and disappeared at 48 h without change in corticosterone levels. Meanwhile dexamethasone produced the same inhibition as delta HOP 5 h after the treatment; this effect disappeared after 18 h. In those animals plasma corticosterone decreased during longer time than in acute treatment, since it continued lower than normal at 18 h and it recovered at 24 h. After 5 h of a chronic treatment delta HOP did not change thymus and spleen weights, but they decreased with dexamethasone treatment. These results suggest that the [quot ]in vivo[quot ] actions of delta HOP is different from that of glucocorticoids.
RESUMEN
The strong inhibition of thymocyte-RNA synthesis by 11 beta-hydroxypregna-1, 4-diene-3, 20-dione (delta HOP) reported recently, fulfills the three conditions required for a non-genomic effect, i.e.: no persistence upon washing out, instantaneous action and effect in the presence of inhibitors of RNA synthesis. Injection of (delta HOP) into mice (2 mg/100 g) also causes a 32
inhibition in their thymocyte-RNA synthesis, but the mechanism of this latter inhibition has still not been clarified.
RESUMEN
The specific uptake of tritiated 18-hydroxycorticosterone (18-OH-B) by purified cell nuclear fractions and cytosol of medulla oblongata, pons, amygdala, anterior pituitary, hypothalamus, hippocampus, preoptic-area and lung from adrenalectomized animals was investigated after incubation of tissue sections with radioactive ligand. We found that 18-OH-B was taken up mainly by nuclei obtained from pons and medulla oblongata; this profile differs from previous observations with the closely related steroids corticosterone and aldosterone, which are mostly concentrated by the limbic system. Based on this finding, as well as on former studies with 18-OH-B, we suggest that this steroid may exert its action on renal excretion of protons as well as on central nervous system structures involved in respiratory regulation, related to that excretion.
RESUMEN
Adrenalectomized rats were injected twice with either 2 micrograms aldosterone or 6 micrograms 18-hydroxycorticosterone (18-OH-B) and were then kept either under normal, or high-CO2 respiratory conditions. Arterial blood samples were withdrawn sequentially from T1 (i.e., 70 minutes after the first injection) on, and were then submitted to determinations of pH and PCO2. Bicarbonate levels were calculated from these data. 18-OH-B: 1) increased pH under both conditions; 2) had a tendency to decrease PCO2 in both conditions; the decrease was significant at 130 minutes after injection, under normal conditions; 3) increased CO3H levels at T1 under high-CO2 atmospheres. Aldosterone did not produce changes in pH values, even if injected in doses equimolar to those of 18-OH-B, but showed a tendency--at these higher doses--to decrease PCO2 values.
RESUMEN
The specific uptake of tritiated 18-hydroxycorticosterone (18-OH-B) by purified cell nuclear fractions and cytosol of medulla oblongata, pons, amygdala, anterior pituitary, hypothalamus, hippocampus, preoptic-area and lung from adrenalectomized animals was investigated after incubation of tissue sections with radioactive ligand. We found that 18-OH-B was taken up mainly by nuclei obtained from pons and medulla oblongata; this profile differs from previous observations with the closely related steroids corticosterone and aldosterone, which are mostly concentrated by the limbic system. Based on this finding, as well as on former studies with 18-OH-B, we suggest that this steroid may exert its action on renal excretion of protons as well as on central nervous system structures involved in respiratory regulation, related to that excretion.