Stimulatory Effect Of Cortisol Research Articles

Cortisol promotes staining-type hypermelanosis in juvenile Japanese flounder

Hypermelanosis of the blind side of Japanese flounder frequently occurs in post-metamorphic juveniles reared in hatcheries. Due to the morphological similarity between darkened blind-side skin and normal ocular-side skin, hypermelanosis is regarded as a transition from normal blind-side skin to that of the ocular side. Hypermelanosis appears only in rearing tanks without sand on the bottom, and its incidence tends to increase under stressful conditions; however, the specific mechanisms responsible for its occurrence have not been identified to date. In teleosts, the hypothalamus-pituitary-interrenal axis (HPI axis) is activated under stress, which then accelerates cortisol secretion. Therefore, in this study, we orally administered cortisol to Japanese flounder to examine its effect on hypermelanosis. The results of our study indicated that cortisol promoted hypermelanosis in a dose-dependent manner. In addition, the effect of cortisol was canceled out in juveniles reared in tanks with bottom sand, suggesting that the well-documented inhibitory effect of bottom sand is stronger than the stimulatory effect of cortisol (i.e., stress) on hypermelanosis. However, administration of the cortisol antagonist RU486 failed to inhibit hypermelanosis, suggesting the contribution of other stimulatory factors to this process. Therefore, our findings strongly suggest that stress-induced cortisol release has the adverse effect of promoting hypermelanosis in juvenile flounders reared without bottom sand.

Cortisol regulates nitric oxide synthase in freshwater and seawater acclimated rainbow trout, Oncorhynchus mykiss

Cortisol and nitric oxide (NO) are regulators of ion transport and metabolic functions in fish. In the gill, they show opposite effects on Na+/K+-ATPase (NKA) activity: cortisol stimulates NKA activity while NO inhibits NKA activity. We hypothesized that cortisol may impact NO production in osmoregulatory tissues by regulating NO synthase (NOS) expression. We evaluated the influence of cortisol treatment on mRNA expression of Nos1 and Nos2 in gill, kidney and middle intestine of both freshwater (FW) and seawater (SW) acclimated rainbow trout and found both tissue- and salinity-dependent effects. Nos2 expression was down-regulated in the gill by cortisol injection in both FW and SW trout. This was substantiated by incubating gill tissue with cortisol ex vivo. Similarly, cortisol injection significantly down-regulated Nos2 expression in kidney of SW fish but not in FW fish. In the middle intestine, Nos2 expression was up-regulated by cortisol injection in FW but unchanged in SW fish. Nos1 expression was up-regulated by cortisol injection in FW kidney and down-regulated in SW kidney, whereas it was unaffected in gill and middle intestine of FW and SW fish. Our data provide the first evidence that cortisol may influence NO production in fish by regulating Nos expression. Indeed, the down-regulation of Nos2 expression by cortisol in the gill may prevent the inhibitory effect of NO on NKA activity thereby furthering the stimulatory effect of cortisol on ion-transport.

Cyclic changes in cortisol across the estrous cycle in parous and nulliparous Asian elephants

In the context of reproduction, glucocorticoids (GCs) are generally considered to have negative effects. However, in well-studied model species, GCs fluctuate predictability across the estrous cycles, and short-term increases promote healthy ovarian function. Reproductive challenges have plagued captive elephant populations, which are not currently self-sustaining. Efforts to understand reproductive dysfunction in elephants have focused on the suppressive effects of cortisol, but the potential permissive or stimulatory effects of cortisol are unknown. In this study, we provide a detailed examination of cortisol patterns across the estrous cycle in Asian elephants (Elephas maximus). Time series analysis was used to analyze cortisol and progesterone data for a total of 73 cycles from eight females. We also compared cortisol profiles between females that successfully conceived and females that failed to conceive despite repeated mating attempts. Our results revealed that cortisol fluctuates predictably across the estrous cycle, with a peak during the second half of the follicular phase followed by low levels throughout the luteal phase. Furthermore, this pattern was significantly altered in nulliparous females; cortisol concentrations did not decline during the luteal phase to the same extent as in parous females. This study highlights the complexity of cortisol signaling and suggests future directions for understanding the role of cortisol in reproductive dysfunction.

Induction of PGF2α Synthesis by Cortisol Through GR Dependent Induction of CBR1 in Human Amnion Fibroblasts

Abundant evidence indicates a pivotal role of prostaglandin F2α (PGF2α) in human parturition. Both the fetal and maternal sides of the fetal membranes synthesize PGF2α. In addition to the synthesis of PGF2α from PGH2 by PGF synthase (PGFS), PGF2α can also be converted from PGE2 by carbonyl reductase 1 (CBR1). Here, we showed that there was concurrent increased production of cortisol and PGF2α in association with the elevation of CBR1 in human amnion obtained at term with labor versus term without labor. In cultured primary human amnion fibroblasts, cortisol (0.01-1μM) increased PGF2α production in a concentration-dependent manner, in parallel with elevation of CBR1 levels. Either siRNA-mediated knockdown of glucocorticoid receptor (GR) expression or GR antagonist RU486 attenuated the induction of CBR1 by cortisol. Chromatin immunoprecipitation (ChIP) showed an increased enrichment of both GR and RNA polymerase II to CBR1 promoter. Knockdown of CBR1 expression with siRNA or inhibition of CBR1 activity with rutin decreased both basal and cortisol-stimulated PGF2α production in human amnion fibroblasts. In conclusion, CBR1 may play a critical role in PGF2α synthesis in human amnion fibroblasts, and cortisol promotes the conversion of PGE2 into PGF2α via GR-mediated induction of CBR1 in human amnion fibroblasts. This stimulatory effect of cortisol on CBR1 expression may partly explain the concurrent increases of cortisol and PGF2α in human amnion tissue with labor, and these findings may account for the increased production of PGF2α in the fetal membranes prior to the onset of labor.

Cortisol Enhances non-REM Sleep and Growth Hormone Secretion in Elderly Subjects

Aging is accompanied by a continuous decline in slow wave sleep (SWS) and in growth hormone (GH) secretion, particularly during the sleeping period. Because short-term pulsatile administration of cortisol increases GH release and SWS in young adults, we wondered whether similar effects can be induced also in elderly men. Hourly injections of cortisol between 1700 and 600 h increased stage 2 and SWS and decreased rapid eye movement sleep. Spectral analysis revealed significant increases in delta and theta power. Cortisol infusions increased the GH secretion prior to sleep onset, but remained largely unchanged during sleep. Thus, sleep EEG and GH release are modulated by cortisol administration in a manner similar to that in young subjects, but to a lesser extent. The stimulatory effect of cortisol on both GH release and SWS points to a mechanism involving glucocorticoid-enhanced production and release of GH-releasing hormone that activates pituitary GH release and simultaneously antagonizes the effects of corticotropin-releasing hormone and somatostatin.

11β-Hydroxysteroid dehydrogenase 1 activity and gene expression in human adipose stromal cells: Effect on aromatase activity

The biological activity of glucocorticoids in target tissues can be influenced by locally produced 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD), the enzyme responsible for the interconversion of cortisol and its inactive metabolite cortisone. In human adipose stromal cells, glucocorticoids are potent stimulators of the conversion of androgens to estrogens (aromatase activity). The present study was designed to determine whether 11 beta-HSD activity was present in human adipose stromal cells, and if changes in the activity of this enzyme could influence aromatase activity. 11 beta-HSD activity was determined by a radiometric conversion assay in breast adipose tissue from six patients. It was found that both dehydrogenase (cortisol to cortisone) and reductase (cortisone to cortisol) activities were present in all six subjects, and the reductase activity was always predominant. Carbenoxolone (CBX), a potent inhibitor of 11 beta-HSD, added to the culture medium at 50 and 200 microM, resulted in 39 +/- 4% and 85 +/- 1% inhibition, respectively, of both reductase and dehydrogenase activity of 11 beta-HSD. To determine whether alterations in 11 beta-HSD could influence aromatase activity, the effect of CBX (200 microM) on cortisol- and cortisone-induced changes in the conversion of androstenedione to estrone was examined. CBX prevented the stimulatory effect of cortisone and minimally potentiated the stimulatory effect of cortisol on aromatase activity, reflecting an inhibition of the local activation of cortisone and the local metabolism of cortisol, respectively. In order to determine whether the product of the 11 beta-HSD 1 gene was responsible for the observed 11 beta-HSD activity, total RNA extracts from these cells were subjected to Northern blot analysis using human 11 beta-HSD 1 cDNA as the probe. A single 1.8 11 beta-HSD 1 transcript was detected, and its abundance was reduced by CBX. No 11 beta-HSD 2 mRNA was detected. The present results demonstrate that the 11 beta-HSD 1 gene is expressed and functional in human breast adipose stromal cells and that changes in 11 beta-HSD 1 activity result in alterations in aromatase activity.

Cortisol enhances the transcription of insulin-like growth factor-binding protein-6 in cultured osteoblasts.

Previous work indicate that glucocorticoids inhibit the synthesis of insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IG-FBP-3), -4, and -5, but not IGFBP-6, in osteoblast cultures. IGFBP-6 binds IGF-II with high affinity and prevents IGF-II-mediated effects. As IGF-II is present at high concentrations in bone, we postulate that glucocorticoids may regulate IGF-II by altering IGFBP-6 synthesis. We tested the expression of IGFBP-6 in cultures of osteoblast-enriched cells from 22-day-old fetal rat calvariae (Ob cells). Treatment of Ob cells with cortisol caused a time- and dose-dependent increase in IGFBP-6 messenger RNA levels, as determined by Northern blot analysis. The effect was maximal after 48 h of treatment and observed with cortisol concentrations of 10 nM to 1 microM. Treatment with cortisol also increased IGFBP-6 polypeptide levels in the medium, as determined by Western immunoblot analysis. Cycloheximide at 3.6 microM decreased IGFBP-6 transcripts and prevented the stimulatory effect of cortisol. Cortisol did not modify the decay of IGFBP-6 messenger RNA in transcriptionally arrested Ob cells. In addition, cortisol increased the rate of IGFBP-6 transcription, as determined by nuclear run-on assays. In conclusion, cortisol stimulates IGFBP-6 expression in Ob cells by transcriptional mechanisms. As IGFBP-6 binds to and prevents the effect of IGF-II, its increased synthesis could be relevant to the inhibitory actions of cortisol in bone.

RETINOIC ACID AND GLUCOCORTICOIDS REGULATE SURFACTANT PROTEIN B GENE EXPRESSION IN HUMAN LUNG EPITHELIAL CELLS. • 337

Surfactant protein B (SP-B) plays a vital role in the pulmonary function of neonates; infants with inherited SP-B deficiency follow a course of progressive and fatal pulmonary failure unless they undergo lung transplantation. In previous studies, we have shown that all-trans retinoic acid (RA), a ligand of the steroid hormone receptor family, increases SP-B mRNA levels in H441 human lung adenocarcinoma cells and in cultured human fetal lung explants. In order to determine the temporal nature of the RA effect on SP-B mRNA, H441 cells were incubated with 10-6M all-trans RA for 1, 2, 4, 8, 12 or 24 hours. The stimulatory effect of all-trans RA on SP-B mRNA levels was observed as early as after 4 hours of exposure to the hormone. We also found that other retinoids, including 9-cis retinoic acid, 13-cis retinoic acid and retinol, do not affect SP-B mRNA levels in the H441 cell line. Glucocorticoids have been shown to increase SP-B mRNA levels in H441 cells and in cultured human fetal lung tissue. We hypothesized that the combination of glucocorticoids and all-trans RA regulates SP-B gene expression in a manner different from the effect of either agent alone. In initial experiments, H441 cells were treated in serum-free medium for 24 hours with cortisol (10-10M to 10-6M) added alone. SP-B mRNA levels were increased compared to control levels in a dose-dependent manner from 1.8 times over control levels in 10-9M cortisol to 4.7 times over control levels in 10-6M cortisol; there was no effect of 10-10M cortisol. H441 cells were then exposed to varying concentrations of cortisol (10-10 M to 10-6M) in the presence of all-trans RA (10-6M). SP-B mRNA levels were further stimulated to 2.8 times control levels in 10-9M cortisol and to 7 times control levels in 10-6M cortisol. At each concentration of cortisol, 10-9M to 10-6M, there was an average 40% increase in the stimulatory effect of cortisol on the level of SP-B mRNA with the addition of 10-6M all-trans RA. These data are suggestive that there is an additive effect of all-trans retinoic acid on cortisol-stimulated surfactant protein B gene expression in human lung epithelial cells.

The role of DNA synthesis in the responses of fetal rat calvariae to cortisol

To determine the extent to which the effects of cortisol on collagen synthesis in 21 day fetal rat calvariae are linked to its effects on cell replication, calvariae were cultured for 24-72 h with 0.1 and 1 microM cortisol in the presence or absence of 1 mM hydroxyurea (HU) or 30 microM aphidicolin (APC), inhibitors of DNA synthesis. The incorporation of [3H]proline into collagenase-digestible protein (CDP) and [3H]thymidine into DNA were measured during the last 2 h of culture. At 24 h HU and APC decreased thymidine incorporation by greater than 90%, and this remained low for the duration of culture. In contrast, cortisol reduced thymidine incorporation by only 44% at 72 h. Although cortisol caused a 24 h stimulatory effect and a 48 and 72 h inhibitory effect on CDP labeling and the percentage of collagen being synthesized (PCS), HU, and APC had no effect on basal CDP labeling or PCS over the 72 h culture period. Cortisol caused parallel alterations in the steady-state levels of alpha-1(I) procollagen mRNA, suggesting that its effects occur at the pretranslational level. At 24 h HU and APC did not prevent the stimulatory effect of cortisol on CDP labeling and PCS. At 48 h the inhibitory effects of cortisol on CDP labeling and PCS were observed in the presence of APC but not in the presence of HU. At 72 h the inhibitory effects of cortisol on CDP labeling and PCS were still observed in the presence of HU and APC.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of cortisol on the synthesis of lamellar body glycerophospholipids in fetal rabbit lung tissue in vitro

The effect of cortisol on the rate of choline incorporation into tissue phosphatidylcholine was investigated in lung explants from fetal rabbits of 19–28 days gestational age. The explants were incubated in medium with or without fetal calf serum for up to 7 days. When lung tissues were incubated in serum-free medium, a stimulatory effect of cortisol on tissue phosphatidylcholine synthesis was found in explants from 21-, 24-, 26- and 28-day fetal rabbits; a stimulatory effect of cortisol was observed in 19-day fetal lung explants only if fetal calf serum was present in the culture medium. To assess directly the effect of cortisol on the synthesis of lamellar body phosphatidylcholine, choline incorporation into phosphatidylcholine associated with a purified lamellar body fraction isolated from lung explants of 21- and 28-day fetal rabbits was also investigated. Cortisol caused a marked stimulation of synthesis and accumulation of lamellar body phosphatidylcholine in lung explants from both 21- and 28-day fetal rabbits. The magnitude of the stimulatory effect of cortisol on the rate of synthesis of lamellar body phosphatidylcholine was always greater than the effect of cortisol on the rate of choline incorporation into lipids of tissue homogenates. The relative rates of synthesis of lamellar body phosphatidylinositol and phosphatidylglycerol were also significantly altered in lung explants from 21- and 28-day fetal rabbits by cortisol treatment. Lamellar bodies that were formed initially in the fetal lung explants were enriched in phosphatidylcholine and phosphatidylinositol and had a relatively low phosphatidylglycerol content. With cortisol treatment there was a decrease in the relative rate of synthesis of lamellar body phosphatidylinositol and an increase in the relative rate of synthesis of phosphatidylglycerol. The stimulatory effect of cortisol on the synthesis of lamellar body phosphatidylcholine was observed at an earlier time-point of incubation than was the effect of cortisol on the relative rates of synthesis of lamellar body phosphatidylinositol and phosphatidylglycerol. The temporal sequence of the cortisol-induced changes in the synthesis of lamellar body glycerophospholipids, therefore, reflects that which occurs with maturation in vivo.

Insulin acts on the fibroblast to inhibit glucocorticoid stimulation of lung maturation.

The effects of insulin and cortisol on saturated phosphatidylcholine synthesis are examined in fetal type II cell cultures and in mixed cell cultures containing type II cells and fibroblasts. In 19-day fetal rat lung type II cell cultures, 100 nM cortisol and 2 nM insulin have no significant effect. Fibroblast-pneumonocyte factor results in enhanced saturated phosphatidylcholine synthesis by fetal type II cells. The significant stimulatory effect of cortisol in mixed-cell cultures is abolished in the presence of insulin or of monoclonal antibodies to fibroblast-pneumonocyte factor. Incubation of type II cells with conditioned media from fibroblasts exposed to cortisol results in increased saturated phosphatidylcholine synthesis. This process is not stimulated when type II cells are incubated with conditioned media from fibroblasts exposed to insulin and cortisol (or to insulin alone). These observations demonstrate that insulin inhibits cortisol induction of lung maturation and suggest that this antagonism results from an inhibitory effect of insulin on the elaboration of fibroblast-pneumonocyte factor by fetal lung fibroblasts.

Cortisol modulation of osteoblast metabolic activity in cultured neonatal rat bone.

The effects of cortisol on basal levels of indices of osteoblast metabolic activity and on PTH regulation of osteoblast activity in vitro were examined in intact bone preparations from neonatal rat calvaria. Uniform punch sections from the frontal portion of calvaria of 3-day-old rats were cultured for 24 h at 37 C in modified BGJb medium. When bone sections were incubated in medium supplemented with cortisol (100 nM) for 24 h, indices of osteoblast metabolic activity, expressed both per total bone section and per micrograms bone DNA, were significantly increased relative to control values. Expressed per micrograms DNA, the following percentage increases were observed in cortisol-treated cultures: alkaline phosphatase activity, +22% (P less than 0.02); [3H] collagen synthesis, +41% (P less than 0.001); and [14C]citrate decarboxylation, + 108% (P less than 0.001). Total DNA per bone section after 24 h was increased by 18% (P less than 0.01), and [3H]thymidine incorporation at 24 h was increased by 26% (P less than 0.01) relative to control values. Stimulation by cortisol occurred in a dose-related manner over concentrations from 1 nM to 1 microM. The stimulatory effects of cortisol were first seen after 6 h of exposure and increased steadily through 24 h of exposure. Incubation in the presence of PTH-(1-34) (100 ng/ml) resulted in significant decrease in alkaline phosphatase activity, collagen synthesis, and citrate decarboxylation after 24 h of exposure (P less than 0.001). The relative order of sensitivity to PTH suppression was identical to the relative sensitivity to cortisol stimulation. In the presence of cortisol (100 nM), the suppressive effect of PTH on all three indices was increased significantly by a factor of 2- to 4-fold. It is concluded that in intact cultured bone, physiological concentrations of cortisol produce both an initial enhancement of indices of osteoblast metabolism and increased osteoblast sensitivity to regulation by PTH.

Multihormonal regulation of surfactant synthesis by human fetal lung in vitro.

Explants prepared from the lung tissue of human abortuses of 20-22 weeks gestational age were incubated in defined medium without serum. These tissues developed the capacity for surfactant synthesis within 4 days. The ductular epithelium differentiated into type II pneumonocytes that contained numerous lamellar bodies. These morphological changes were accompanied by an increase in the rate of choline incorporation into phosphatidylcholine as well as an increase in the phosphatidylcholine content of the explants. Cortisol (0.2 micrograms/ml) plus PRL (2.5 micrograms/ml), when added to the medium from the beginning of the culture period, caused a 2- to 3-fold increase in the rate of choline incorporation into phosphatidylcholine, as measured on the second, fourth, sixth, and eighth days of incubation, as well as an increase in the phosphatidylcholine content of the explants. However, when administered alone, neither cortisol nor PRL affected phosphatidylcholine synthesis. In explants incubated with cortisol plus PRL there also was a stimulation of lamellar body secretion into the prealveolar ducts. The lamellar bodies in epithelial cells were larger in cortisol- plus PRL-treated tissue than those in nontreated tissues. Increases in phosphatidylcholine synthesis and lamellar body secretion also were observed in tissues incubated with insulin (2.5 micrograms/ml), cortisol, and PRL in combination or with insulin and cortisol in combination. The stimulatory effect of cortisol plus insulin on phosphatidylcholine synthesis, however, was significantly less than that of cortisol plus PRL or cortisol plus insulin plus PRL. It is suggested that human fetal lung development is under multihormonal control and that PRL and cortisol serve to increase surfactant synthesis and secretion.

Cortisol enhancement of PTH-stimulated cyclic AMP accumulation in cultured fetal rat long bone rudiments

Cortisol in concentrations from 10 nM to 10 microM produced a dose-related inhibition of basal and PTH1-stimulated 45Ca and [3H]-hydroxyproline release from cultured fetal rat forelimb rudiments. PTH-stimulated cyclic AMP generation however was not diminished by cortisol; in contrast, at a concentration of 1 microM cortisol produced a 57% increase in PTH-stimulated bone cyclic AMP content. The stimulatory effect of cortisol on cyclic AMP content appeared to be the result of reduced phosphodiesterase activity, since this effect was not seen in the presence of 10 mM theophylline. It is concluded that cortisol inhibition of PTH-induced resorption in long bones is not accompanied by reduced cyclic AMP generation.

Cortisol and the Adventitious Root Formation in Mung Bean Seedlings

Summary The effect of cortisol on the adventitious root formation on the hypocotyls of intact mung bean seedlings and on mung bean cuttings has been studied. Under different physiological conditions cortisol greatly increased the number of adventitious roots formed and also the total number of adventitious roots and initials formed on the hypocotyls of intact mung bean seedlings. The best growth conditions were found to be 25 °C in the dark. In intact seedlings growing in the dark at 25 °C, the cortisol sensitive phase for adventitious root formation was between the second and fourth day of the 6 d growth period. Cortisol was not required during the first day nor after the fourth day of growth. In mung bean cuttings the stimulatory effect of cortisol on adventitious root formation was less pronounced, but there was a significant increase in the total number of roots and initials. In both intact seedlings and cuttings cortisol application provoked a double effect: whereas the formation of initials was stimulated, their outgrowth became limited by the cortisol treatment. Our results suggested that cortisol (or its metabolite[s]) or a factor released by it from the roots was transported to the hypocotyls. The results are discussed in view of the possible occurrence of corticosteroid like compounds in higher plants.

The effects of cortisol and amino acids on the metabolic activity of rat skin stored in dimethyl sulfoxide buffer at - 196 degrees C.

Abstract Addition of amino acids to the DMSO buffer reduces the intracellular amino acid depletion of rat skin tissue frozen and stored at −196 °C. Although prolonged exposure to DMSO progressively inhibits the [2- 14 C]glycine and l -[U- 14 C]leucine incorporation into the proteins, cortisol and amino acid additions to the buffer medium protect the protein-synthesizing activity. These factors also stimulate the incorporation of [6- 3 H]-thymidine into DNA. The stimulatory characteristics of cortisol and of amino acids separately are enhanced when both components are added together to the preserving buffer. These effects are noticeable in tissue only exposed to the DMSO buffer without freezing as well as in skin frozen and stored at −196 °C and subsequently thawed at 40 °C. A stimulatory effect of cortisol and of a free amino acid, supplement to the medium on the α-amino-[1- 14 C]isobutyric acid uptake by the cells is only observed in skin exposed for a short period of time to the DMSO buffer, but it is not detectable after longer exposure and after freezing.

Cortisol stimulation of parathyroid hormone secretion by rat parathyroid glands in organ culture.

Addition of cortisol (10(-6) to 10(-8) M) and related glucocorticoid congeners to cultures of rat parathyroid glands stimulated dose-related increases in parathyroid hormone secretion; the addition of deoxycorticosterone or cortexolone was without effect. Cortexolone, however, inhibited the stimulatory activity of cortisol when both were added to the culture medium. This direct stimulatory effect of cortisol on parathyroid gland secretion may account in part for the increased concentration of parathyroid hormone in the serum of cortisol-treated animals.