High Doses Of Hydrocortisone Research Articles

Evidence that high dose cortisol-induced Na+ retention in man is not mediated by the mineralocorticoid receptor.

We have previously shown that high dose cortisol (F; 240 mg/day)-induced Na retention and systolic blood pressure (BP) increases are not inhibited by the glucocorticoid (type II) receptor antagonist RU486. Adequacy of type II receptor blockade with RU486 was clearly demonstrated, indicating that the Na retention was not mediated through the glucocorticoid receptor. Spironolactone (Sp; 400 mg/day), in a preliminary assessment, also did not inhibit F-induced Na retention. The purpose of this study was to determine whether the Na retention produced by F administration is mediated by the type I receptor by comparing the effects of F to a potent type I agonist [9a-fludrohydrocortisone (9aFF)] with and without Sp administration. The effects of the two agonists and Sp on urinary K excretion and BP were also compared. Normal male volunteers, on a constant daily diet for 10 days, received either F (240 nig/ day) or 9aFF (3.0 mg/day) with or without Sp (400 mg/day) for the last 5 days. The mean cumulative reductions in Na excretion during the 5 days compared to baseline values before hormone administration were 255 ± 38 and 494 ± 81 mmol/5 days for F (n = 9) and 9aFF (n = 5), respectively (P = 0.01). Sp (n = 5) completely inhibited 9aFF-induced Na retention (494 ± 81 vs. -37 ± 130 mmol/5 days; P < 0.01), but had no effect (n = 5) on F-induced Na retention (255 ± 38 us. 193 ± 50 mmol/5 days; P = NS). After the expected first day kaliuresis, the effects of both steroids on net cumulative urinary K excretion were minimal. Systolic BP was increased by F, but not 9aFF, and Sp did not inhibit this increase. A 2-fold greater Sp-inhibitable Na-retaining effect of the mineralocorticoid demonstrates that the failure of Sp to block F-induced Na retention is not due to inadequate type I receptor blockade. Based on these findings and earlier studies, we conclude that high dose (stress level) Finduced Na retention and systolic BP increase are not mediated by either the mineraloor glucocorticoid receptor in normal man. (J Clin Endocrinol Metab 72: 1060-1066,1991) ORTISOL (F) has mineralocorticoid as well as glucocorticoid effects (1), and it also binds to both type I (mineralocorticoid) and type II (glucocorticoid) receptors in renal cytosol in man (2, 3). However, the effects of F on renal electrolyte excretion are poorly understood. Acute administration of F variably produces either natriuresis or Na retention, but always kaliuresis; these changes may be associated with an increase in the glomerular filtration rate (GFR) (1). Comparison of the renal effects of F to those of more potent synthetic glucocorticoids has led to the conclusion that the increased GFR, acute kaliuresis, and associated natriuresis are glucocorticoid effects (1, 4-6). The Na-retaining Received October 2,1990. Address requests for reprints to: C. O. Watlington, M.D., Endocrine Division, Department of Medicine, MCV Station, Box 145, Richmond, Virginia 23298-0145. * This work was supported by NIH Grants R01-DK-35341 and R01DK-36822, Clinical Research Center Grant RR-00065, and a Grant-InAid from the A. D. Williams Foundation. t Postdoctoral fellow supported by NHLBI Training Grant HL07110. $ Recipient of a Clinical Associate Physician Award from the NIH. effects of F, more clearly demonstrable after the first 12 h of administration (5), are considered to be mediated by renal type I receptor activation (7). We have recently described the effects of RU38486 (RU486), a potent type II receptor antagonist, on the changes in urinary Na and K excretion produced by high dose F over a 5-day period in normal man (8). Despite ample evidence for adequate glucocorticoid blockade, RU486 did not alter F-induced urinary Na retention. These studies suggested that the Na retention was not mediated by type II receptors. Administration of the type I receptor antagonist spironolactone (Sp) at a dosage of 400 mg/day also did not inhibit F (240 mg/ day)-induced Na retention and only blunted a lesser effect produced by a lower dosage (120 mg/day). These findings raised the possibility that high dose F produces Na retention by a mechanism mediated by neither type I nor type II receptor activation. However, the evidence for adequacy of type I receptor blockade was not definitive (see Discussion). The present study was designed to determine whether F-induced Na retention is mediated

Depletion of luteal phase serum progesterone during constant infusion of cortisol phosphate in the cynomolgus monkey

To study the impact of chronic infusions of cortisol phosphate on ovarian function in the cynomolgus monkey. Cortisol phosphate at doses of 5 or 15 mg/d or saline were infused for periods of up to 8 weeks using subcutaneously implanted osmotic pumps. Animals were maintained in the Center for Experimental Animal Resources, Northwestern University. Serum total and unbound cortisol concentrations, serum total and unbound progesterone (P) concentrations, urinary P metabolites. Mean increases in serum cortisol of 56% and 77% above control levels were achieved. Mean serum P concentrations were not decreased with low-dose cortisol phosphate infusion during the 12 days preceding menses, but mean serum P levels were decreased by 69% to 2.3 ng/mL during high-dose cortisol phosphate infusion. No corresponding decrease in excretion of conjugated immunoreactive P metabolites was found in daily urine samples during cortisol phosphate infusion, suggesting that production rates of P were unaltered by the cortisol phosphate treatment. Unbound serum cortisol increased by a mean of 162% above control levels during high-dose cortisol phosphate infusion, but no increase occurred in the percentage of unbound serum P. We conclude that elevation of serum cortisol in the range observed in chronically stressed individuals may severely decrease the available P to target organs by displacement of P from plasma proteins but does not inhibit ovarian steroidogenesis or ovulation.

Evidence That High Dose Cortisol-Induced Na+Retention in Man Is not Mediated by the Mineralocorticoid Receptor*

We have previously shown that high dose cortisol (F; 240 mg/day)-induced Na+ retention and systolic blood pressure (BP) increases are not inhibited by the glucocorticoid (type II) receptor antagonist RU486. Adequacy of type II receptor blockade with RU486 was clearly demonstrated, indicating that the Na+ retention was not mediated through the glucocorticoid receptor. Spironolactone (Sp: 400 mg/day), in a preliminary assessment, also did not inhibit F-induced Na+ retention. The purpose of this study was to determine whether the Na+ retention produced by F administration is mediated by the type I receptor by comparing the effects of F to a potent type I agonist [9 alpha-fludrohydrocortisone (9 alpha FF)] with and without Sp administration. The effects of the two agonists and Sp on urinary K excretion and BP were also compared. Normal male volunteers, on a constant daily diet for 10 days, received either F (240 mg/day) or 9 alpha FF (3.0 mg/day) with or without Sp (400 mg/day) for the last 5 days. The mean cumulative reductions in Na+ excretion during the 5 days compared to baseline values before hormone administration were 255 +/- 38 and 494 +/- 81 mmol/5 days for F (n = 9) and 9 alpha FF (n = 5), respectively (P = 0.01). Sp (n = 5) completely inhibited 9 alpha FF-induced Na+ retention (494 +/- 81 vs. -37 +/- 130 mmol/5 days; P less than 0.01), but had no effect (n = 5) on F-induced Na+ retention (255 +/- 38 vs. 193 +/- 50 mmol/5 days; P = NS). After the expected first day kaliuresis, the effects of both steroids on net cumulative urinary K+ excretion were minimal. Systolic BP was increased by F, but not 9 alpha FF, and Sp did not inhibit this increase. A 2-fold greater Sp-inhibitable Na(+)-retaining effect of the mineralocorticoid demonstrates that the failure of Sp to block F-induced Na+ retention is not due to inadequate type I receptor blockade. Based on these findings and earlier studies, we conclude that high dose (stress level) F-induced Na+ retention and systolic BP increase are not mediated by either the mineralo- or glucocorticoid receptor in normal man.

Talc granulomatosis in the rat

We investigated the dynamics of the acute-phase response (APR) and osteoblast trabecular surface in rats with subcutaneous inflammation provoked by magnesium silicate (talc). The first visible indicator of the APR was a rapid and profound hypozincemia, paralleled by a decrease in metaphyseal trabecular surfaces covered with osteoblasts in long bones. Both the intensity of serum APR and the decrease in osteoblast trabecular surface were directly proportional to the number of granulomas. Alterations in bone metabolism were specific for the inflammation, whereas mild hypozincemia and decrease in mononuclear and increase in polymorphonuclear peripheral white blood cell fractions developed in animals pair-fed with rats bearing two or four granulomas. Rats with talc granulomatosis had high serum ACTH and corticosterone levels, but neither adrenalectomy nor high doses of hydrocortisone could revert bone alterations in talc-injected animals. Glucocorticoids were necessary for the development of hypozincemia and hypercupremia seen in talc granulomatosis, as well as for normal bone metabolism. Inhibition of prostaglandin synthesis had no effect on bone alterations and serum APR in rats bearing talc-induced granulomas. We conclude that the decrease in bone formation constitutes an important aspect of the host acute-phase response in a rat model of talc granulomatosis.

Cortisol Alters Gene Expression during Involution of the Rat Ventral Prostate

The ability of high doses of cortisol to retard the involution process in the rat ventral prostate was related to alterations in the pattern of gene expression. Poly(A)+ RNA preparations from the prostates of noncastrated, castrated, and castrated rats injected daily for 7 days with cortisol were compared by Northern blot hybridizations for the relative expression of genes associated with cell differentiation and maintenance (the C1 prostatic steroid binding protein gene and alpha-tubulin), with cell death (TRPM-2, hsp 70, and c-fos), and with hormone regulation (the androgen and glucocorticoid receptors). As anticipated, the concentration of C1 mRNA in the prostate fell to less than 4% of that in the noncastrated controls within 4 days after castration and was nearly undetectable after 7 days. This decline was retarded by cortisol treatment of 7-day castrated animals which sustained the level of C1 transcripts at approximately 50% of control. While the pattern of expression of alpha-tubulin indicated some minor fluctuations, with the highest level occurring 7 days after castration, the prostates of the cortisol-treated group had essentially the same concentration of this mRNA as the noncastrates. Cortisol also modified the expression of genes associated with prostatic cell death. The large increase in prostatic TRPM-2 mRNA, seen 7 days after castration, was reduced by over 80% after treatment with the glucocorticoid. Although not as abundantly expressed as TRPM-2, the castration-induced levels of transcripts for both hsp 70 and the protooncogene c-fos were substantially reduced by cortisol.(ABSTRACT TRUNCATED AT 250 WORDS)

Endocrine effects of aminoglutethimide plus hydrocortisone versus effects of high dose of hydrocortisone alone in postmenopausal metastatic breast cancer

Aminoglutethimide (Ag) has been used in different dosages with and without combined treatment with glucocorticoids for the suppression of peripheral plasma levels of steroidal hormones. In the present work we have estimated changes in peripheral steroid levels after 3 days of adrenal suppression with a ‘physiological’ daily dose of 40 mg hydrocortisone (H). Subsequently Ag (1000 mg daily) was added or the dose of H was doubled in order to study the efficacy of the suppression of oestradiol by these conditions during a 6-week period. Sixteen postmenopausal patients with evaluable and measurable progressive breast cancer were selected for the initial treatment, thereafter Ag was added in eight patients, while the other eight patients continuedon H with a double dose. Administration of 40 mg H daily during the first 3 days caused a significant decrease of plasma oestradiol ( P < 0.01), androstenedione ( P < 0.01) and DHEA-S ( P < 0.05). Basal plasma cortisol levels increasedandthe diurnal rhythm disappeared. These observations suggest suppression of adrenal function by the exogenous cortisol. Prolonged treatment with a higher dose of H (80 mg daily) caused further suppression of androstenedione ( P < 0.01) but not of oestradiol. The addition of 1000 mg of Ag to H had no further significant effect on plasma oestradiol levels either. The main difference between the effects of the two treatment modalities was in the levels of androgens. The group treated with H alone showed long-term significant suppression of both androstenedione and DHEA-S, while in the group treated with the combination of H + Ag a further pronounced suppression of DHEA-S and elevation of androstenedione was found. Finally, there was a significant difference between SHBG levels in the two groups at day 42. The increased levels of SHBG in the H + Ag-treated group might lower the ‘free’ oestradiol concentration. It is concluded that both drugs have different effects on the plasma levels of peripheral steroids. On theoretical grounds, the combination of H + Ag might be preferable, because ‘free’ oestradiol plasma levels may be lowest after this treatment. However, a direct correlation with clinical effects still remains to be proven.

Technetium-99m imaging of bone trauma: reduced sensitivity caused by hydrocortisone in rabbits.

This study evaluates the effect of hydrocortisone on the sensitivity of 99mTc-scintigraphy for the detection of bone trauma in three groups of rabbits: a control group that received no hydrocortisone, a low-dose group that received 0.8 mg/kg/day, and a high-dose group that received 20 mg/kg/day. Scintigrams of the tibial diaphyses were obtained at 48 hr, 1 week, 2 weeks, and 3 weeks after surgical creation of a simulated fracture (a 1.5-mm hole in the cortex). The mean sensitivity for detecting fractures in control animals was 95% at 48 hr and 100% at all other times. Mean sensitivity for rabbits given the high dose of hydrocortisone was 41% at 48 hr. Mean sensitivity for the low-dose group was 75% at 48 hr, but this was not significantly different from the control group. Sensitivity in both groups treated with hydrocortisone improved with time. At 3 weeks, the mean was 93% in the low-dose group and 83% in the high-dose group. These data suggest that 99mTc scintigraphy may be less sensitive in detecting bone trauma in patients on glucocorticoid therapy than in patients in the general population.

Changes in blood glucose, liver glycogen, ketone bodies and plasma insulin in suckling rats treated with a single high cortisol dose one day after birth.

Rats treated with cortisol, 0.5 mg one day after birth, show a decrease in body and organ weight and a decrease in pituitary TSH and GH when compared to controls together with a lack of response of TSH to TRH. These alterations have been previously found in animals treated with large doses of thyroxine, neo-T4 syndrome, in both populations a brain underdevelopment has been observed. Plasma insulin in cortisol-treated animals was higher (P less than 0.01) than in the controls at 8 and 12 days of life and lower at 22 days (P less than 0.001). Plasma ketone bodies were increased significantly at 8 but not at 12 and 22 days of life in the cortisol treated animals. Liver glycogen was higher than in controls at 2, 4, 6 days of life and lower at 8, 12 and 22 days. Blood glucose was higher than in controls at 2, 4 days and lower at 6, 8, 12 and 22 days of life. The timing of metabolic events is important for the adaptation and development of the post-natal animal. The perturbances in carbohydrate metabolism in suckling rats were also previously found in neo-T4 rats during the period when the brain growth spurt and energy need are the greatest; but in the rats treated with cortisol the timing of the alterations was different. This different timing of the metabolic perturbances could correlate with a different maturation in cerebral tissue found in histological studies in the two populations.

Endocrine effects of Aminoglutethimide (Ag) plus Hydrocortisone (HC) versus high dose of hydrocortisone in postmenopausal breast cancer

Endocrine effects of Aminoglutethimide (Ag) plus Hydrocortisone (HC) versus high dose of hydrocortisone in postmenopausal breast cancer

Hereditary joint disorder in progressive ankylosis (ank/ank) mice. II. Effect of high-dose hydrocortisone treatment on inflammation and intraarticular calcium hydroxyapatite deposits.

Mice homozygous for the progressive ankylosis trait develop an inflammatory joint disorder associated with the intraarticular deposition of calcium hydroxyapatite. When affected (ank/ank) mice were treated with high doses of hydrocortisone, synovitis receded, development of cartilaginous and bony osteophytes halted, and calcium hydroxyapatite accumulated in and distended the synovial spaces. No changes, however, occurred in the joint morphology of hydrocortisone-treated normal (ank/+) mice. Since inhibition of inflammation by hydrocortisone treatment did not block apatite accumulation, intraarticular deposition of hydroxyapatite occurs independent of inflammation in progressive ankylosis.

Ultrastructure of the Nucleus Pulposus in the Intervertebral Disc After Systemic Administration of Hydrocortisone in Mice

The nucleus pulposus of the lumbar intervertebral disc of mice given daily intramuscular injection of hydrocortisone at a dose of 1, 5, 10 mg/kg body weight for 1-4 weeks from 2 weeks of age was studied by electron microscopy. The hydrocortisone administration induced degeneration of the notochordal cells in the nucleus pulposus. The degenerative changes occurred earlier in the periphery of the nucleus pulposus than in the central region and developed earlier in mice treated with higher doses of hydrocortisone than in mice treated with lower doses. From the results, it is likely that steroid treatment accelerates the aging process of the nucleus pulposus and causes dysfunction of the intervertebral disc.

The effect of oxytocin, estrogen, calcium ionophore A23187 and hydrocortisone on prostaglandin F 2α and 6-oxo-prostaglandin F 1α production by cultured human endometrial and myometrial explants

Normal human endometrium (classified by histology and date after last menstrual period) was cultured for 72h, and the output of prostaglandin F 2α and 6-oxo-prostaglandin Fla detected by radioimmunoassay. Hormones/stimuli were added to the culture during the second day of culture for 5h and 19h periods. 1. 1) The output of prostaglandin F 2α from cultured endometrium was significantly higher (p<0.05) at the beginning (d4–8) and end (d25–30) of the menstrual cycle, compared to mid-cycle (d13–24) endometrium. Significantly more prostaglandin F 2α was released from proliferative than from secretory phase endometrium (p<0.02). 2. 2) Prostaglandin F 2α release was rapidly stimulated by sodium arachidonate (20–300 μg/ml), and by calcium ionophore A23187 (5 μg/ml) at an extracellular calcium ion concentration of 1.8mM.The ionophore stimulation was greater in mid-cycle endometrium than in endometrium from the beginning or the end of the menstrual cycle. 3. 3) Estradiol-17β (10 ng/ml) gradually increased the output of prostaglandin F 2α from secretory phase endometrium, and this stimulation was observed in the post-incubation period after hormone had been removed from the incubation medium. 4. 4) Oxytocin (1 × 10 −5U/ml caused a more rapid stimulation of prostaglandin F 2α output from secretory phase tissue (p<0.05 during the first 5h incubation period with hormone). 5. 5) Oxytocin (1 × 10 −5 U/ml) and estradiol (long/ml) together significantly stimulated prostaglandin F2a production by proliferative as well as secretory phase endometria. 6. 6) A high dose of hydrocortisone (loo μg/ml) inhibited the output of prostaglandin F 2α from proliferative and secretory phase endometrium and also from ionophore-stimulated endometrium. However, this dose of hydrocortisone did not inhibit the synthesis of prostaglandin F2a from exogenous arachidonic acid, or the estradiol-induced increase in prostaglandin F 2α production. 7. 7) Co-culture of endometrium with myometrium did not modify the output of prostaglandin F 2α or of 6-oxo-prostaglandin Fla from cultured tissues. 8. 8) These experiments suggest that arachidonic acid supply to the cyclooxygenase enzyme may vary during the menstrual cycle: and indicate a gradual increase in prostaglandin synthesising capacity in response to estrogen, more rapid control via oxytocin, and an interaction between estrogen and oxytocin to modulate prostaglandin F2a synthesis in human endometrium.

Effect of excessive vitamin A intake on muscle protein turnover in the rat.

3-Methylhistidine excretion in vivo and in vitro was monitored in hypervitaminotic and pair-fed control rats. Feeding with excess of retinyl palmitate (40 000 i.u./day per 100 g body wt.) significantly increased urinary 3-methylhistidine and creatinine output during a 4-day treatment interval. 3-Methylhistidine release from perfused rat hindquarters was also elevated after 5 days of vitamin treatment. To determine whether the adrenals were involved in mediating the above response, a study was conducted on adrenalectomized and sham-operated rats. Excessive vitamin A intake stimulated 3-methylhistidine excretion in vivo and in vitro in both adrenalectomized and sham-operated animals, thus suggesting that the vitamin A-induced acceleration in myofibrillar protein breakdown was not mediated by the adrenals. In both groups of rats, vitamin A treatment had no effect on the rate of protein synthesis, on the basis of incorporation in vitro of [3H]phenylalanine into muscle protein. Additional studies revealed that the addition of excess retinol to the perfusion medium (10 i.u./ml) had no significant effect on the rates of 3-methylhistidine release or [3H]phenylalanine incorporation in vitro. Finally, high doses of cortisol (7 mg/day per 100g body wt.) administered to intact rats for 5 days significantly increased rates of 3-methylhistidine excretion, both in vivo and in vitro.

Comparative study of glucocorticoid sensitivity and receptors in lymphoid tissues

Glucocorticoid sensitivity of different lymphoid tissues of avian and mammalian origin was investigated. As a measure of glucocorticoid effect variation of thymidine kinase activity was selected. By this method an order of sensitivity was established among various species and tissues. Dexamethasone uptake by isolated lymphocytes and specific binding to cytosol receptors was also examined. No direct correlation was found between glucocorticoid sensitivity and either binding capacity (receptor number per cell) or affinity of receptor for hormone. The presence of one homogeneous binding site was detected in each tissue examined both by isolated cell technique and cytosol saturation analysis in the range of 1–40 nM of [ 3H]-dexamethasone concentration. In all cases about 80% of the bound dexamethasone was associated with cell nucleus in our system. Dexamethasone binding of the hydrocortisone resistant subpopulation of chicken lymphoid tissues was studied after in vivo treatment with high doses of hydrocortisone. The surviving cells contained an amount of dexamethasone receptor cell similar to that of the whole population. A theoretical analysis of the steady-state receptor cycle gives an explanation for the differences between the values of K A determined in intact cells or in cellfree systems.

Selective inhibition by sodium butyrate of the glucocorticoid induction of glycerol phosphate dehydrogenase in glial cultures

We examined the effect of millimolar concentrations of the short chain fatty acid, n-butyrate, on the induction of two cytoplasmic enzymes in the C6 rat glioma cell line. Hydrocortisone addition to the culture medium produced a 2- to 3.5-fold induction of glycerol phosphate dehydrogenase after 24 h, and norepinephrine produced a 2-fold increase in lactate dehydrogenase activity in this time period. Five mM sodium butyrate completely abolished the glucocorticoid-mediated response, while the catecholamine-mediated response was unaffected. This selective inhibition was rapid and reversible, and did not affect the level of cytoplasmic steroid binding. Furthermore, high doses of hydrocortisone did not overcome the inhibition. Finally, this phenomenon was also seen in primary cultures of pure oligodendrocytes.

The differential actions of cortisol on the accumulation of α-lactalbumin and casein in midpregnant mouse mammary gland in culture

The dose-response relationship between cortisol and the accumulation of the two milk proteins, casein and α-lactalbumin, was studied in organ culture of mammary gland from midpregnant mice. The accumulation of casein was low in culture with insulin but was enhanced by the further addition of prolactin. Further increases in casein were effected by the addition of cortisol in increasing concentrations up to 3 × 10 −6 M, which was optimal for the accumulation of this protein. The content of α-lactalbumin in explants was similarly low in culture with insulin alone, but, in contrast, was increased to a maximal level by the addition of insulin and prolactin. The addition of cortisol up to 3 × 10 −8 M with insulin and prolactin did not further increase the level of α-lactalbumin; in fact, at concentrations above 3 × 10 −7 M the steroid caused progressive inhibition of the accumulation of this protein in cultured explants. Studies of the appearance of casein and α-lactalbumin in incubation medium during organ culture revealed the presence of substantial amounts of these milk proteins. During the first 2 days of culture with insulin, prolactin and 3 × 10 −6 M cortisol, the amount of α-lactalbumin in culture medium was almost equal to the level found in tissue, whereas in the presence of 3 × 10 −8 M cortisol, or in the absence of exogenous steroid, over 70% of total α-lactalbumin was retained in tissue. The observed difference in the amount of α-lactalbumin in culture medium can, however, only partially account for the inhibitory effect of high doses of cortisol on the accumulation of α-lactalbumin in cultured mammary explants. In contrast to α-lactalbumin, the relative amount of casein in culture medium containing insulin and prolactin was smaller—19% of total casein synthesized—and was further reduced to 16% and 11% of the total in the presence of 3 × 10 −8 M and 3 × 10 −6 M cortisol, respectively. The above results indicate that cortisol exerts dose-dependent differential actions on the accumulation of casein and α-lactalbumin in mouse mammary epithelium in vitro.

Correlation Between Natural and Antibody-Dependent Cell-Mediated Cytotoxicity Against Tumor Targets in the Mouse. II. Characterization of the Effector Cells

Direct comparison of the effector cells mediating natural killer (NK) activity against mouse tumor cells and antibody-dependent cell-mediated cytotoxicity (ADCC) against mouse tumor target cells coated with alloantisera indicated that NK cells and K-cells (effector cells mediating ADCC) may belong to the same subpopulation of lymphocytes, but they have a different mechanism of killing. Effector cells mediating NK activity and ADCC were nonadherent, nonphagocytic Fc receptor-bearing cells that sediment at 3.5-4.5 mm/hour. Treatment with anti-Thy 1.2 serum in the absence of complement resulted in an increase of NK activity, whereas this treatment caused a substantial loss in ADCC. Both NK activity and ADCC were equally sensitive to the in vivo or in vitro effects of X-irridiation. In vivo inoculations of high doses of hydrocortisone resulted in a reduction of NK activity, but ADCC was not affected. NK cells were trypsin-sensitive, with a profound decrease in the cytolytic activity being observed in a 4-hour 51Cr release assay. The activity, however, could be recovered after overnight incubation at 37 degrees C. Trypsin treatment did not inhibit ADCC as measured by the 18-hour assay.

Sensitivity to glucocorticoids of lymph node cells stimulated in vivo by oxazolone.

Sensitization of B10.A mice with oxazolone results in delayed-type hypersensitivity (DTH) and a two to three-fold increase in the weight of regional lymph nodes by the third day. Hydrocortisone treatment of the animals 3 days after sensitization suppresses the manifestation of DTH on the tenth day but not on the seventieth day and significantly decreases the weight of lymph nodes both in control and oxazolone-sensitized mice. The regional lymph node cells of oxazolone-stimulated mice were, like the controls, sensitive to dexamethasone in vitro, as judged by viability and thymidine incorporation. Dexamethasone binding capacity of the regional lymph node cells 72 h after oxazolone sensitization increased. However, the dissociation constant for dexamethasone, the binding specificity, and the nuclear transfer of the hormone were not altered. Since high doses of hydrocortisone given 3 days after sensitization were unable to erase permanently the DTH to oxazolone, it seems very likely that cells responsible for the immunological memory survive the high dose of hydrocortisone.

Differences in inducibility by glucocorticoids of rat liver TO and TAT.

The modulation of tryptophan-oxygenase (TO) and tyrosine amino-transferase (TAT) in the rat liver after a single dose of hydrocortisone has been studied under various physiological conditions. Differences in the induction behavior of the two enzymes have been observed dependent on sex, age, amount of administered hormone, and presence or absence of the adrenals. Some of the results observed are the following: 1) TO reached its maximum induction level 3 h prior to TAT in normal male rats. This difference disappeared when adrenalectomized male rats or when female animals were tested. 2) The maximal induction values of both enzymes were 50--80% higher in adrenalectomized rats than in normal rats. This effect was independent of sex. 3) Higher doses of hydrocortisone were necessary for optimal induction of TO and TAT in normal than in adrenalectomized rats. 4) The minimum dose of hydrocortisone necessary for enzyme induction was significantly lower for TO than for TAT. 5) Actinomycin D caused a complete inhibition of the induction of TO and TAT when given simultaneously with the glucocorticoid. The inhibition was less complete the longer the interval between hormone and actinomycin D administration. The activity of TAT was suppressed to a larger extent than TO.

The Stability of Vitamin A-induced Metaplasia of Mouse Vibrissa Follicles In Vitro

Tests were made of the stability of the previously described glandular morphogenesis and mucous metaplasia of embryonic mouse vibrissa follicles produced in vitro by excess vitamin A. The changes in individual follicles were observed in living tissue explants and serial sections. Upper lip skin of 13.5-day embryos underwent budding from vibrissa follicles to form branching glands which secreted mucus after 10--14 days in medium containing 4.7 microgram/ml retinol. If this medium was replaced with standard medium after 7 days, glandular morphogenesis and metaplasia continued unaffected, although some hair follicle bases returned to their original morphogenetic program. Similar results were obtained with skin of 13-day embryos treated with vitamin A (6.0 MG/ML) for only 3 days. The moderate degree of glandular morphogenesis in 15-day skin with vitamin A (4.7 microgram/ml) was not altered by the simultaneous addition of a high dose of cortisol (18 microgram/ml). It is suggested that the initiation of glandular morphogenesis of follicles differs from the initiation of mucous metaplasia in embryonic chick epidermis by vitamin A, in that it resembles a new secondary embryonic induction rather than a modulation of the epithelium.