Influence of cortisol on the synthesis of sulfated mucopolysaccharides and collagen in chick embryos

The effect of serum growth factors and xyloside on molecular aging of proteoglycan in embryonal chick cartilage

The effects of normal human serum, insulin-like growth factor and beta-D-xyloside on the synthesis of proteoglycan, as well as their differential effect on the synthesis of chondroitin sulfate and keratan sulfate side-chains, were studied in chick embryonal cartilage. The glycosaminoglycans found in the incubation medium were mainly intact carbohydrate moieties of partially degraded proteoglycan molecules, whereas the tissue-bound glycosaminoglycans were of intact proteoglycan molecules. In incubations with normal human serum, the synthesis of the chondroitin sulfate side-chains of the tissue-bound glycosaminoglycans was preferentially stimulated, while the percentage of medium glycosaminoglycan (out of the total glycosaminoglycan in tissue and medium) was reduced, compared to control incubations. In incubations with insulin-like growth factor, the synthesis of the keratan sulfate side-chains of the tissue-bound glycosaminoglycan was preferentially stimulated, whereas the percentage of the medium glycosaminoglycan resembled that of control incubations. In incubations with xyloside, a marked reduction of tissue-bound glycosaminoglycan was noticed, mainly of chondroitin sulfate chains, and only a slight decrease in keratan sulfate chains. Human serum of various age groups stimulated proteoglycan synthesis in embryonal chick cartilage to almost the same extent. However, sera from babies and adults were found to stimulate chondroitin sulfate chains preferentially, whereas serum of aged subjects preferentially enhanced the synthesis of keratan sulfate chains. These findings suggest that the synthesis and/or degradation of the various types of glycosaminoglycan chains (chondroitin sulfate and keratan sulfate) of cartilage proteoglycan can be regulated differentially by serum growth factors. Secondly, the growth hormone-mediated serum factor (insulin-like growth factor) seems to play a role in molecular aging of proteoglycans.

Zonal analysis of cytoplasmic steroid hormone receptor levels: replication and synthetic activity in embryonic calf growth cartilage

Using the dextran charcoal method, a specific steroid receptor for dexamethasone, but not 17 beta-estradiol or 17 alpha-methyltrienolone, was demonstrated in cytosol prepared from mid-gestation fetal calf growth cartilage. Zonal analysis of cytoplasmic receptor levels showed that tissue sections from the center, the peripheral surface, and the palisade section bound 229 +/- 111, 173 +/- 64, and 15 +/- 28 femtomole dexamethasone per mg of protein, respectively. Incorporation of 3H-thymidine, 35S-sulfate, and 3H-proline into cartilaginous tissues was used as an index of replication and synthetic activity. The percentage of 3H-thymidine labeled nuclei, as determined by radioautography, showed that the palisade zone has a significantly lower replicating activity (P less than 0.001). Values were 5.6 +/- 1.2, 5.4 +/- 1.2, 3.8 +/- 1.3, and 1.1 +/- 0.2 for the center, peripheral surface, and upper and lower half of the palisade section. The rate of sulfate and proline incorporation into the palisade zone was over seven times higher than the central and peripheral surface (P less than 0.001). The difference in the rate of matrix synthesis and proliferating activity in these regions may be related to the zonal heterogeneity of receptor levels of glucocorticoids in fetal growth cartilage.

Effect of five anti-inflammatory steroids on collagen and glycoaminoglycan synthessis in vitro

The effect of five anti-inflammatory corticosteroids, i.e. hydrocortisone, hydrocortisone 17-butyrate, betamethasone 17-valerate, nicocortonide acetate and nicocortonide, on the synthesis of hyaluronic acid, sulphated glycosaminoglycans and collagen by cultured skin fibroblasts was studied. As inhibitors of all these parameters the steroids could be arranged in order hydrocortisone < hydrocortisone 17-butyrate < betamethasone 17-valerate, nicocortonide acetate and nicocortonide. The corticosteroid concentrations required for inhibition of hyaluronic acid were very low as compared to those required for inhibition of sulphated glycosaminoglycan and collagen synthesis.

Effects of corticosteroids on the growth and metabolism of fibroblasts cultured from human skin

Hydrocortisone, betamethasone 17-valerate, clobetasone butyrate and clobetasol propionate were tested in vitro for effects on the proliferation and metabolism of six strains of fibroblasts from normal human skin. The different cell strains gave similar results: hydrocortisone and betamethasone valerate slightly enhanced growth at all concentrations (0.0001-10 microgram/ml), but high concentrations of clobetasone butyrate and clobetasol propionate significantly reduced proliferation. Secretion of acid mucopolysaccharide was most inhibited by clobetasone butyrate and clobetasol propionate, then by betamethasone valerate, with hydrocortisone having the least effect. Clobetasol propionate and betamethasone valerate at 10 microgram/ml both reduced collagen synthesis by about 50%; other protein synthesis was less affected.

Effects of glucocorticosteroids on primary human skin fibroblasts. II. Effects on total protein and collagen biosynthesis by confluent cell cultures

Confluent cultures of normal primary human skin fibroblasts were incubated with various glucocorticosteroids which are in current use clinically for the treatment of various skin disorders. For all steroids concentrations were found at which collagen hydroxyproline formation was inhibited, while total protein synthesis was little affected. The concentration effective for inhibition was highest for hydrocortisone and lowest for clobetasol-17-propionate. All other steroids (hydrocortisone-17-butyrate, triamcinolone acetonide and betamethasone-17-valerate) showed medium effectiveness. Fluorination as such was not a factor in the degree of inhibition. The inhibition observed was shown to be independent of concomitant specific effects on cell proliferation or cell turnover. The possible implications of these findings on the therapeutic effects in psoriasis and the frequently occurring atrophic side-effects of these steroids are discussed.

Stimulation of cartilage macromolecule synthesis by adenosine 3',5'-monophosphate

The role of cyclic AMP in the regulation of cartilage macromolecule synthesis in vitro was studied in pelvic cartilage from 10-12 day chick embryos. Incubation of cartilages in medium containing 0.5 mM cyclic AMP resulted in a 30% inhibition of 35SO4-2, [3H]leucine and [3H]uridine incorporation into proteoglycan, total protein and RNA, respectively. Higher concentrations of cyclic AMP had no greater effects. In contrast, butyrylated cyclic AMP derivatives (0.5-5.0 mM) added to the incubation medium stimulated (50-100%) the incorporation of these radiolabeled precursors into cartilage macromolecules. Theophylline, in concentrations (0.1-0.5 mM) which raise intracellular cyclic AMP, also increases the incorporation of radiolabeled precursors into macromolecules. The data indicate that exogenous cyclic AMP and butyrylated cyclic AMP derivatives have paradoxical effects on cartilage macromolecule synthesis. Butyrylated cyclic AMP derivatives, not exogenous cyclic AMP, mimic the effects of intracellular cyclic AMP. Incubation of embryonic chicken cartilage with exogenous cyclic AMP results in the extracellular degradation of the cyclic AMP to adenosine. Adenosine (0.125 mM) inhibits precursor incorporation into cartilage macromolecules. The metabolism of exogenous cyclic AMP generates sufficient adenosine to account for the observed inhibitory effects of exogenous cyclic AMP on cartilage macromolecule synthesis. Butyrylated cyclic AMP derivatives are not degraded during incubation with cartilage. The data indicate that cartilage is a tissue in which the effect of cyclic AMP is to stimulate anabolic processes.

Effect of hydrocortisone on the growth of choroid plexus and composition of cerebrospinal fluid in the developing chick embryo

The effect of hydrocortisone on the telencephalic choroid plexus and on the osmolarity and ionic compositon of CSF was studied 48 hours after its administration onto the chorio-allantoic membrane of chick embryos on days 11 and 13 (20 mug per egg) or on day 17 (40 mug per egg). Hydrocortisone significantly reduced the choroid plexus area on days 13 and 15 but was ineffective on day 19. The topical analysis of these choroid plexuses, influenced by the steroid, pointed to a decrease of the growth activity in those parts whose proliferation was intensive. The transient population of villi in the apical part of these plexuses was the most sensitive. Those parts, being morphogenetically inactive or whose morphogenetic changes were not caused by the cellular proliferstion, were not affected significantly. The osmolarity of CSF increased significantly during the investigated period simultaneously with an increase in the sodium and chloride concentration while the concentrations of potassium did not change significantly. Hydrocortisone evoked a precocious increase in the osmolarity of CSF on days 13 and 15. Contemporarily, the potassium concentration in CSF was elevated while the steroid failed to change the sodium and chloride concentrations.

Glucocorticoid and starvation effect on glycosaminoglycans in vascular connective tissue. Biochemical studies on repair processes in rabbit aorta

Male rabbits were injured by a single mechanical dilatation injury of aorta and then injected with prednisone 2 mg/kg or saline for 14 days or subjected to starvation. The biosynthesis of the sulfated glycosaminoglycans as evaluated by the uptake of 35S-sulfate and the content of the glycosaminoglycans were measured on the intima-media layer of the descending thoracic aorta. The results indicate that prednisone may inhibit the biosynthesis of heparan and/or dermatan sulfate while starvation increases the biosynthesis of all the sulfated glycosaminoglycans. No alterations were observed in the total amount of glycosaminoglycans in aorta following glucocorticoid injection or starvation. The metabolism of aortic glycosaminoglycans during repair is less sensitive to the action of prednisone than in undamaged aorta. This contrasts with the effect of prednisone on the metabolism of aortic collagen.

The effects of exogenous cortisone acetate on development (especially skeletal development) and on circulating levels of corticosteroids in chick embryos

Chick embryos were treated with cortisone acetate on day 8 of incubation and the subsequent growth of the whole embryo and the development of the tibia studied to day 18 of incubation. Cortisone, at 10 ng to 2 mg/embryo decreased general body growth; above 0.5 mg/embryo it also retarded morphogenesis by as much as 3 Hamilton-Hamburger stages; and above 1 mg/embryo gross abnormalities were produced. The growth and differentiation of the tibia were affected to a greater extent than was the whole body. The reductions in tibial and total body weight were not linearly related to dose of cortisone injected. The exogenous cortisone acetate resulted in drastic alterations in the circulating levels of cortisone, cortisol, corticosterone, and progesterone, but plasma progesterone level was most readily correlated with the growth retardation. This study emphasizes that avian embryos can readily compensate for exogenous corticosteroids and that caution must be exercised when attributing causality to the substance administered.

Effects of topical glucocorticoid medication on collagen biosynthesis in the dental pulp

The aim of the study was to observe pulpal collagen synthesis in response to trauma and to glucocorticoid medication. The material consisted of 290 rabbit pulps and 76 human premolar pulps. Collagen synthesis was determined by incubating whole pulps in a medium containing [14C]proline, and measuring the formation of [14C]hydroxyproline. The effect of glucocorticoids was studied in vitro using rabbit pulps. Hydrocortisone and dexamethasone inhibited collagen synthesis, whereas prednisolone had no marked effect. Hydrocortisone was found to inhibit the synthesis of [14C]hydroxyproline in neutral salt soluble and insoluble non-dialyzable collagen fractions. [14C]hydroxyproline in the dialyzable fraction was increased, suggesting that hydrocortisone increased collagen degradation. In the human material, premolar pulps were experimentally exposed and then medicated with capping agents. The contralateral teeth were exposed and capped with other capping materials, in some cases they were left as intact controls. The exposure led to an increase in the collagen synthesis as indicated by increased [14C]hydroxyproline formation and elevated protocollagen proline hydroxylase activity in the pulp. This enzyme activity was suppressed in pulps capped with a glucocorticoid paste. In addition, the collagen synthesis rate was lower in pulps treated with another glucocorticoid containing compound, when compared to pulps capped with a calcium hydroxide preparation.