Effect of hydrocortisone on phenylhydrazine-induced Heinz-body anemia

The effect of hydrocortisone on phenylhydrazine-induced anemia has been examined in adrenalectomized rats. The extent of hemolysis in adrenalectomized rats treated with phenylhydrazine was significantly higher than in normal and adrenalectomized rats supplemented with hydrocortisone.     

Dexamethasone and glucagon cause synergistic increases of urea cycle enzyme activities in livers of normal but not adrenalectomized rats.

Adrenalectomized and intact rats were given constant high-dose infusions of glucagon, 0.3 mg/kg per day for 7 days, with or without low-dose dexamethasone, 0.01 mg/kg daily, to test whether glucocorticoids potentiate glucagon induction of the 5 urea cycle enzymes as they do in cultured rat hepatocytes. Glucagon did not induce any of the urea cycle enzymes in adrenalectomized Sprague-Dawley rats and only induced argininosuccinate lyase (EC 4.3.2.1) in adrenalectomized inbred Wistar-Furth rats. Dexamethasone alone induced arginase in adrenalectomized and in intact Wistar-Furth rats and restored the other enzymes to normal levels in adrenalectomized rats. In intact Wistar-Furth rats, the combination of hormones gave synergistic increases of all 5 enzymes over the responses to each hormone alone, but in adrenalectomized rats the combination was only additive or less than additive compared with the sum of single hormone responses. The lack of synergism between the two hormones in adrenalectomized rats suggest that other factors play a role in glucagon induction of this cycle.     

Influence of tryptophan on the activity of acetylcholinesterase in the brain of well-fed normal and adrenalectomized rats

Eight hours after a single tube-feeding of tryptophan the activity of acetylcholinesterase in the cerebral hemisphere of well-fed (non-fasted) normal and adrenalectomized rats was 28 and 53% higher, respectively, compared to the corresponding water-fed control. On the other hand, the enzyme activity in the cerebellum of both normal and adrenalectomized rats remained essentially unchanged following tryptophan administration. Pretreatment of adrenalectomized rats with actinomycin-D totally abolished the tryptophan-mediated stimulation of cerebral acetylcholinesterase activity. The pattern of response of cerebral acetylcholinesterase in well-fed adrenalectomized rats over a period of 24-hr following a dose of tryptophan was found to be biphasic.     

Effects of adrenalectomy on hormone action on hepatic glucose metabolism. Impaired glucagon activation of glycogen phosphorylase in hepatocytes from adrenalectomized rats.

The effects of adrenalectomy on glucagon activation of liver glycogen phosphorylase and glycogenolysis were studied in isolated hepatocytes. Adrenalectomy resulted in reduced responsiveness of glycogenolysis and phosphorylase to glucagon activation. Stimulation of cAMP accumulation and cAMP-dependent protein kinase activity by glucagon was unaltered in cells from adrenalectomized rats. Adrenalectomy did not alter the proportion of type I and type II protein kinase isozymes in liver, whereas this was changed by fasting. Activation of phosphorylase kinase by glucagon was reduced in hepatocytes from adrenalectomized rats, although the half-maximal effective concentration of glucagon was unchanged. No difference in phosphorylase phosphatase activity between liver cells from control and adrenalectomized rats was detected. Glucagon-activated phosphorylase declined rapidly in hepatocytes from adrenalectomized rats, whereas the time course of cAMP increase in response to glucagon was normal. Addition of glucose (15 mM) rapidly inactivated glucagon-stimulated phosphorylase in both adrenalectomized and control rat hepatocytes. The inactivation by glucose was reversed by increasing glucagon concentration in cells from control rats, but was accelerated in cells from adrenalectomized rats. It is concluded that impaired activation of phosphorylase kinase contributes to the reduced glucagon stimulation of hepatic glycogenolysis in adrenalectomized rats. The possible role of changes in phosphorylase phosphatase is discussed.     

Changes in glucocorticoid receptors in different regions of brain of immature and mature male rats

Specific cytosolic binding for synthetic glucocorticoid dexamethasone was studied in several brain regions (hypothalamus, hippocampus, caudate nucleus, cerebellum, cerebral cortex) of immature (3-week) and mature (26-week) male rats, intact and adrenalectomized. A significant regional difference was observed in the concentration of in vitro [3H] dexamethasone binding in the brain of adrenalectomized rats at both ages, with the highest levels in the hippocampus. A marked decrease in specific binding was observed in all brain regions of adrenalectomized mature rats as compared to immature. The dexamethasone binding was significantly lower in all brain regions of normal intact animals as compared to adrenalectomized rats in both ages.     

Studies on adrenaline-induced lipolysis in adrenalectomized rats.

In a short-term study, adrenaline-induced lipolysis was less in adrenalectomized rats than in controls, though the cyclic AMP accumulation was not different. In adrenalectomized rats treated with corticosterone, lipase activity was as low as in untreated adrenalectomized rats, although adrenaline-induced lipolysis was not reduced. In a long-term study, no reduction in adrenaline-induced lipolysis or cyclic AMP accumulation was observed in adrenalectomized rats. The mechanism of the effect of adrenalectomy on adrenaline-induced lipolysis is discussed on the basis of these results.     

Tryptophan force-feeding: Changes in the activities of acetylcholinesterase in various tissues of well-fed normal and adrenalectomized rats

The activity of acetylcholinesterase in the liver, heart, spleen, lungs and kidneys of well-fed normal and adrenalectomized rats was measured following a single tube-feeding of tryptophan. In well-fed normal rats, 30 min after tryptophan force-feeding, the enzyme activity in the heart and lungs was stimulated by 28 and 25% as compared to the water-fed control while in well-fed adrenalectomized rats acetylcholinesterase acticity in the heart, liver spleen and lungs was 40, 31, 22 and 15% increased, respectively over that of the corresponding control. In both groups of rats the enzyme activity in the kidney was unaffected by tryptophan. In the liver, spleen and heart of well-fed adrenalectomized rats the pattern of response for acetylcholinesterase to a tryptophan dose, over a period of 24-hr. was found to be biphasic. In well-fed adrenalectomized rats the tryptophan-mediated stimulation of acetylcholinesterase activity in the heart was found to be insensitive to actinomycin-D. The tryptophan-mediated stimulation of acetylcholinesterase activity in the heart of well-fed normal and adrenalectomized rats could not be related to the presence of an activator.     

Synergistic effects of thyroxine and glucocorticoid in induction of trypsin-like esteroprotease in mouse submandibular gland.

The actions of thyroxine, 5 alpha-dihydrotestosterone and hydrocortisone singly or in combination in enzyme regulation in the submandibular gland were studied in intact and adrenalectomized female mice. 1. Adrenalectomy decreased the activity of trypsin-like esteroprotease (EC 3.4.4.-), and administration of hydrocortisone to adrenalectomized mice restored the activity to normal. 2. Hydrocortisone and thyroxine had synergistic effects in induction of esteroprotease in adrenalectomized mice, but 5 alpha-dihydrotestosterone and hydrocortisone did not have synergistic effects in either intact or adrenalectomized mice. 3. The activity of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) was not influenced by change in the glucocorticoid level, but was increased by thyroxine and 5 alpha-dihydrotestosterone in both adrenalectomized mice and intact mice.4. Isoelectric focusing in polyacrylamide gel showed that there are three distinct activities of esteroprotease in this gland with isoelectric points of 5.6, 6.2 and 7.3. Both thyroxine and 5 alpha-dihydrotestosterone similarly induced these activities and glucocorticoids did not affected the isozyme patterns induced by the other two hormones.     

Modulation of glucocorticoid effect in thymus of adrenalectomized-diabetic rat

Cellular receptors to glucocorticoids and the effect of dexamethasone and corticosterone on 3H-uridine incorporation into the acid-insoluble fraction were studied in thymocytes from adrenalectomized-diabetic rats and adrenalectomized ones. An increase in the dissociation constant of the hormone-receptor plot was observed when adrenalectomized-diabetic animals were compared to adrenalectomized controls. Meanwhile decreasing concentrations of dexamethasone and corticosterone below receptors saturation, were less active as inhibitor of 3H-uridine incorporation into RNA by thymocytes from adrenalectomized-diabetic than from adrenalectomized ones.     

Suppressive effect of adrenalectomy on growth of L1210 leukemic cells in ascites

This study was designed to evaluate the effect of adrenalectomy on growth of L1210 leukemic cells in ascites of BDF1 mice. Varying doses of 1.5 x 10(4), 5.0 x 10(5), and 1.5 x 10(6) viable tumour cells were inoculated intraperitoneally into groups of either adrenalectomized or sham-operated mice. At days 4 to 7 after the inoculation, adrenalectomized mice inoculated with 1.5 x 10(4) or 5.0 x 10(5) tumour cells had a smaller number of tumour cells in ascites than sham-operated controls. However, after inoculation of 1.5 x 10(6) cells, no significant differences were found at days 2 to 4 between adrenalectomized and sham-operated mice. The growth retardation by adrenalectomy was not observed in adrenalectomized mice supplemented with 4 or 6 micrograms dexamethasone per day per mouse. It suggested that the ablation of glucocorticoids was at least partially responsible for the growth retardation observed in adrenalectomized mice. Cell kinetic analysis revealed that the difference in a potential doubling time could not explain these results. Tumour retention in the peritoneal cavity was measured using [125I]-iododeoxyuridine-labelled tumour cells as a tracer. At days 4 to 6 after inoculation of 5.0 x 10(5) labelled cells, radioactivity in the peritoneal cavity in adrenalectomized mice was about 70 per cent of that in sham-operated mice. This ratio was almost equivalent to the ratio of the number of cells in ascites of adrenalectomized mice to that of sham-operated ones. Consequently, growth retardation observed in adrenalectomized mice resulted from an increase in tumour cell migration and/or in tumour cell death, but not from an increase in doubling time.     

Behavioral effects of L-tryptophan and p-chlorophenylalanine after adrenalectomy or dexamethasone administration in rats

Effects of acute administration of L-tryptophan (L-TRP. 250.0 mg/kg, i.p.) on active avoidance conditioning and "open-field" behavior were studied in male rats after adrenalectomy of dexamethasone administration. L-TRP inhibited the acquisition and reproduction of active avoidance reaction in adrenalectomized and dexamethasone-treated rats. Moreover, L-TRP decreased horizontal locomotor activity and grooming behavior in the "open field" on adrenalectomized rats. On the contrary, p-CPA restored the active avoidance conditioning in adrenalectomized rats and rats with excess of glucocorticoids. Also, p-CPA increased the total locomotor activity and grooming behavior in the "open field" in adrenalectomized rats, but decreased horizontal locomotor activity and enhanced emotional reaction in dexamethasone-treated rats in the "open field".     

皮质酮对大鼠再生肝细胞转录活性的影响

以AgNOR颗粒数为指标，研究大鼠部分肝切除后，皮质酮对余留肝细胞转录活性的影响。结果显示：部分肝切除后0～24h，各组肝细胞内(假手术、去肾上腺、去肾上腺 皮质酮)AgNOR颗粒数均下降；部分肝切除后36h，假手术鼠的AgNOR数目最多，到48h时已基本恢复到肝切除前水平；在部分肝切除后24～48h，去肾上腺鼠的AgNOR颗粒数持续升高；给去肾上腺鼠再注射剂量分别为10、20、40mg／kg体重的皮质酮，发现在36h和48h时，皮质酮剂量越高，AgNOR颗粒数日越少，且下降幅度越大。部分肝切除前12h给大鼠注射糖皮质激素受体颉颃剂——RU486(10mg／kg体重)，结果与去肾上腺鼠相似。以上结果表明：皮质酮对部分肝切除后肝细胞的转录活性具有明显的抑制作用，而且是通过受体起作用，该作用表现在部分肝切除24h之后。     

Adrenalectomy of Rats Results in Hypomyelination of the Central Nervous System

The effect of adrenalectomy on CNS myelin accumulation was investigated to determine whether glucocorticoids play a role in regulating myelination. When 14-day-old rats were adrenalectomized and sacrificed 7-8 days later, the amount of bulk-isolated myelin in whole brain, as expressed per gram wet weight of brain or per milligram DNA-phosphate, was reduced to about 75% that of sham-operated controls. Both brain weight and DNA content were unchanged by adrenalectomy. Examination of individual brain regions also revealed decreased amounts of myelin in adrenalectomized animals. Brain glycerol 3-phosphate dehydrogenase specific activity was reduced in adrenalectomized animals to 40-60% that of controls, and serum corticosterone levels were less than 0.6% of control levels. The amount of cerebral myelin in animals adrenalectomized on day 21 and sacrificed 9 days later was not significantly reduced. This suggests a possible role of glucocorticoids during the early period of rapid myelination.     

Antagonism of anethole and adrenal extract on glycogen formation in adrenalectomized rats

Anise oil, anethole, and several related compounds inhibit the deposition of glycogen in the livers of fasted, adrenalectomized rats by adrenal cortical extract. This effect is reversed by increased levels of adrenal extract.Anethole blocks the effect of adrenal cortical hormones in reducing insulin sensitivity of adrenalectomized rats.Adrenal hypertropy of unilaterally adrenalectomized rats is increased by anethole.It is postulated that these compounds compete for an active carbohydrate intermediate formed during glycogenesis.The possible role of β-glucuronidase is also pointed out.     

Incorporation of 3H-2,3-DL-valine into pancreatic proteins of adrenalectomized rats stimulated with pancreozymin-CCK and secretin

Incorporation of labelled valine was investigated in bilaterally adrenalectomized rats stimulated with pancreozymin-CCK and secretin 14 days after operation. The growth of rats, the blood pressure, the amount of pancreatic juice and the amylase output was less in the adrenalectomized animals as compared with sham operated or adrenalectomized and corticosterone substituted controls. The amylase concentration in the pancreatic juice reveals no difference between the groups but the output of amylase remained below that of the controls. The incorporation of labelled valine was higher in the pancreatic tissue and proteins in the adrenalectomized animals than in the controls. It is assumed that the adrenalectomy causes primarily a depletion in the metabolic activity and systemic blood pressure; diminished pancreatic juice secretion and output of amylase are only secondary consequences which are not compensable by hormonal stimulation of pancreatic secretion.     

Effect of naloxone on physostigmine-induced pressor response in adrenalectomized rats

Physostigmine-induced pressor response was studied in adrenalectomized rats. The increase in mean arterial blood pressure elicited by intravenous administration of physostigmine was not altered by adrenalectomy or sham-operation. The pressor response to intracerebroventricular administration of physostigmine was found to be partially inhibited in both acutely adrenalectomized and sham-operated rats, but not in those adrenalectomized 24 h earlier. This inhibition was completely prevented by naloxone pretreatment. The results suggest that endogenous opioid peptide release induced by surgical stress may be responsible for inhibition of the pressor effect of centrally administered physostigmine in rats.     

Beta-adrenergic control of phosphatidylcholine synthesis by transmethylation in hepatocytes from juvenile, adult and adrenalectomized rats.

Changes in isoprenaline-sensitive phospholipid methyltransferase were studied in hepatocytes isolated from juvenile, mature and adrenalectomized rats. Isoprenaline produced greater stimulation of cyclic AMP accumulation in juvenile and mature adrenalectomized rats than in mature animals. Similarly, isoprenaline stimulated phospholipid methyltransferase in juvenile and mature adrenalectomized rats but had no effect in mature animals. Isoprenaline-mediated activation of phospholipid methyltransferase in adrenalectomized rats was time- and dose-dependent. In hepatocytes isolated from adrenalectomized rats incubated with [Me-3H]methionine or [3H]-ethanolamine the addition of isoprenaline increased the amount of radioactivity incorporated into phosphatidylcholine. The activation by isoprenaline of phospholipid methyltransferase was abolished by the beta-blocker propranolol and by insulin. These results indicate that rat liver the occupation of functional beta-receptors causes a stimulation of phospholipid methylation. It is suggested that, as reported previously, cyclic AMP activates phospholipid methyltransferase.     

Glucose and ketone bodies production in hepatocytes isolated from fetuses at term--II. Effect of maternal adrenalectomy

Glucose and ketone bodies production has been studied in hepatocytes isolated from fetuses at term of fed and fasted adrenalectomized mothers. Maternal adrenalectomy diminishes the fetal liver weight. This effect is increased when the adrenalectomized pregnant rat is fasted for the last 2 days of gestation. Maternal adrenalectomy diminishes glucose production in hepatocytes isolated from fetuses at term. This diminution is markedly greater when the adrenalectomized pregnant rat is fasted for the last 48 hr of gestation. Maternal adrenalectomy diminishes ketone bodies production in hepatocytes isolated from fetuses at term.     

Adrenocorticotropic (ACTH) cells of rats after head irradiation.

The heads of intact rats and of rats 15 days after adrenalectomy were irradiated with 1200 R. Some of the adrenalectomized animals with irradiated heads were treated with 5 mg of deoxycorticosterone acetate. In adrenocorticotropic cells of adrenalectomized rats 15 and 30 days after irradiation, the decreased amount of the granular endoplasmic reticulum and the Golgi regression imply a considerably decreased protein synthesis. The finding of an increased number of granules and of granules larger than normal suggests that they are the result of slowed down transport and secretion of the products of these cells' activities. After head irradiation an increased number of degenerative cells was evident in the pituitary of both intact and adrenalectomized rats. The degree of the degenerative changes and the number of degenerative cells was higher 30 than 15 days after irradiation and both were decreased if the adrenalectomized rats were treated with deoxycorticosterone acetate.     

Effect of prostaglandin E1 administration on the heart glycogen synthase and phosphorylase systems

The effects of intravenous administration of PGE₁ on the glycogen synthase and phosphorylase system in rat heart were studied.Unlike the consistent effects of PGE₁ on glycogen synthase in liver, the response in heart was variable. A significant decrease in the per cent synthase occurred in fasted intact rats while a significant increase was seen in adrenalectomized hydrocortisone treated fasted rats. No significant effect was seen on the synthase system in either fed intact or fasted adrenalectomized rats.Phosphorylase activity was increased significantly following PGE₁ administration in fed intact rats and slightly increased in adrenalectomized fasted rats. The phosphorylase system was not affected in fasted intact and fasted adrenalectomized rats given glucocorticoid replacement. With our present state of knowledge an adequate explanation for the response of these heart enzymes to PGE₁ under the various conditions of this study does not appear possible.