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Benznidazole-induced ultrastructural alterations in rat adrenal cortex. Mechanistic studies.

Benznidazole (Bz) (N-benzyl-2-nitro-1-imidazole acetamide) is a drug used against Chagas' disease, a parasitic disease afflicting several millions of Latin Americans. Bz administration to Sprague-Dawley male rats at 100 mg/kg p.o. caused subcellular alterations in the adrenal cortex involving fasciculata and reticularis zones but not in the glomerulosa. There is Bz nitroreductase activity in the adrenal microsomal and mitochondrial fractions but most of it is localized in mitochondria. Activity in the two fractions requires NADPH under anaerobic conditions. Mitochondrial Bz nitroreductase activity was inhibited by oxygen. A minor but statistically significant inhibition was observed in mixtures incubated under carbon monoxide. Microsomal Bz nitroreductase activity was not detected under oxygen atmosphere and was not inhibited under carbon monoxide. No Bz nitroreductase activity mediated by xanthine oxidase or aldehyde oxidase was detected in the cytosolic fraction from rat adrenals. Electron microscopic examination of the adrenal cortex from Bz-treated animals revealed cells with marked lipid accumulation and alterations in nuclei, endoplasmic reticulum and mitochondria in the reticularis and fasciculata zones. In vitro results suggest a Bz nitroreductive activation, with minor or null P-450 participation, leading to reactive metabolites able to cause damage in various organelles.

Administration, Oral↗

[Autoregulation of hormonogenesis in the adrenal cortex].

Experiments were conducted on 60 rats. An attempt was made to ascertain with the aid of histochemical methods the possibility of a direct action of glucocorticoids on the adrenal glands. Incomplete coincidence of histochemical changes following hypophysectomy with the changes caused by the action of cortisone for the same period (10 days), and also a distinct depression with cortisone of histochemical shifts characteristic of the action of ACTH in hypophysectomized animals pointed to the direct (not mediated through the hypophysis) influence of cortisone on the adrenal cortex.

Acid Phosphatase↗

The effects of freezing and cryoprotectant exposure on adenylate cyclase activity in cell membranes of bovine thyroid gland and adrenal cortex.

We present data on the effect of freezing with or without cryoprotectant (CPA) dimethyl sulphoxide (Me(2)SO), as well as effects of exposure to CPA alone on the activity of adenylate cyclase in cellular membranes of thyroid glands and adrenal cortex. Our results show that freezing without cryoprotectant increases unstimulated adenylate cyclase activity and decreases sensitivity to specific regulators. CPA at a concentration of 5% for adenylate cyclase in adrenal cortex tissue and of 10% in thyroid gland allowed preservation of the best responses to specific receptor agonists.

Adenylyl Cyclases↗

[Functions of the adrenal cortex in patients with supratentorial brain tumors and their prognostic value for surgical intervention].

The functional activity of the adrenal cortex was studied pre- and postoperatively in patients with pituitary adenomas, craiopharyngiomas and supratentorial meningiomas. With the hypothalamus function preserved, the patients developed varying degrees of stress-responses in the postoperative period. Severe morphological injuries to the hypothalamus make the normal response to surgical trauma impossible. With some functional centers preserved, the diencephalo-catabolic syndrome develops. Severe injuries of the diencephalon, with its adaptative function completely lost, result in the development of the diencephalic areactive syndrome.

11-Hydroxycorticosteroids↗

Ad4BP in the human adrenal cortex and its disorders.

Ad4BP, a zinc finger DNA-binding protein, is a transcription factor that regulates the expression of the steroidogenic P450 genes. We performed immunoblotting and immunohistochemistry of Ad4BP in 34 human adrenal cortex specimens, which included adrenocortical adenomas and carcinomas. Immunoblotting revealed a single band of 53K, corresponding to the mol wt of Ad4BP. The immunohistochemical studies demonstrated that Ad4BP immunoreactivity was present exclusively in the nuclei of nearly all of the adrenocortical parenchymal cells in both the normal and the pathological human adrenal specimens. Ad4BP was immunostained with equal intensity and frequency among the different cell types. Ad4BP immunoreactivity was also observed in areas of marked degenerative changes, such as lipomyelomatous lesions, and in poorly differentiated carcinoma cells. These results suggest a close association of Ad4BP expression with the biological phenotype of adrenocortical parenchymal cells. Ad4BP therefore seems to play important roles in the induction and maintenance of the transcription of all steroidogenic P450 genes in human adrenocortical cells, even after malignant transformation.

Adenoma↗

Regulation of the fetal human adrenal cortex: effects of adrenocorticotropin on growth and function of monolayer cultures of fetal and definitive zone cells.

Monolayer cultures have been prepared from both definitive and fetal zones of the human fetal adrenal cortex. Cultures from each zone consist predominately of adrenocortical cells, as determined by a specific morphological retraction response to ACTH, and by ACTH-induced inhibition of DNA synthesis and cell proliferation. Cell growth was stimulated by fibroblast growth factor. ACTH stimulated steroidogenesis in cells from each zone with an ED50 of 0.4--1.0 nM and at a maximal concentration of 5 nM. Short term stimulation of less than 24 h with ACTH produced a pattern of steroid secretion that was characteristic of the zone of origin. Definitive zone cultures produced both cortisol and dehydroepiandrosterone plus its sulfate (DHA/S), with cortisol production exceeding DHA/S production. Fetal zone cultures produced more DHA/S than cortisol. 3 beta-Hydroxysteroid dehydrogenase, delta 4,5-isomerase enzyme activity was 3-fold less in fetal than in definitive zone cultures. Long term stimulation of 1--4 days with ACTH, 8-bromo-cAMP, or cholera toxin increased steroidogenic capacity in cultures from both zones. The pattern of steroid production by definitive zone cells remained constant, but cortisol production was preferentially increased in fetal zone cells. Forty-eight-hour treatment of fetal zone cells with ACTH increased 3 beta-hydroxysteroid dehydrogenase, delta 4,5-isomerase activity 5-fold. alpha-, beta-, gamma 1-, gamma 2-, and gamma 3-MSH were not effective steroidogenic agents for either zone. These studies indicate that steroidogenic agents induce in fetal zone cells steroid production characteristic of definitive and adult adrenocortical cells.

Adrenal Cortex↗

Purification and characterization of 3 beta-hydroxysteroid-dehydrogenase/isomerase from bovine adrenal cortex.

The formation of 4-ene-3-ketosteroids from 3 beta-hydroxy-5-ene precursors is an obligatory step in the biosynthesis of hormonal steroids such as glucocorticoids, mineralocorticoids, estrogens and androgens. In the adrenal cortex, pregnenolone, 17 alpha-hydroxy-pregnenolone and dehydroisoandrosterone are converted to progesterone, 17 alpha-hydroxy-progesterone and androstenedione, respectively, by the enzymatic system 3 beta-hydroxy-5-ene steroid dehydrogenase and 3-keto-5-ene steroid isomerase (3 beta-HSD/I). The present work reports a two step purification procedure which yields an homogenous preparation of 3 beta-HSD/I from bovine adrenal cortex. It uses solubilization of the microsomal proteins followed by two chromatographic steps, i.e. DEAE-cellulose and heparine-sepharose columns. The enzyme was obtained as an homogeneous protein exhibiting an apparent molecular size of 45 kDa upon SDS-gel electrophoresis and of 81 kDa upon gel filtration. The purified enzyme exhibits both the 5-ene-3 beta-ol steroid dehydrogenase and isomerase activities in contrast to previous work using a more complex procedure which yielded a final preparation having lost its isomerase activity [Hiwatashi et al., Biochem. J. 98 (1985) 1519-1525]. N-terminal aminoacid (29 residues) sequence of the purified protein was determined and was found identical to that predicted from the nucleic acid sequence of the recently identified enzyme cDNA [Zhas et al. FEBS Lett. 259 (1989) 153-157].

3-Hydroxysteroid Dehydrogenases↗

Purification and characterization of a phosphoprotein phosphatase from bovine adrenal cortex.

A phosphoprotein phosphatase which is active against chemically phosphorylated protamine has been purified about 500-fold from bovine adrenal cortex. The enzyme has a pH optimum between 7.5 and 8.0, and has an apparent Km for phosphoprotamine of about 50 muM. The hydrolysis of phosphoprotamine is stimulated by salt, and by Mn2+. Hydrolysis of phosphoprotamine is inhibited by ATP, ADP, AMP, and Pi, but is not affected by AMP or cyclic GMP. The purified phosphoprotein phosphatase preparation also dephosphorylates p-nitrophenyl phosphate and phosphohistone, and catalyzes the inactivation of liver phosphorylase, the inactivation of muscle phosphorylase a (and its conversion to phosphorylase b), and the inactivation of muscle phosphorylase b kinase. Phosphatase activities against phosphoprotamine and muscle phosphorylase a copurify over the last three stages of purification. Phosphoprotamine inhibits phosphorylase phosphatase activity, and muscle phosphorylase a inhibits the dephosphorylation of phosphoprotamine. These results suggest that one enzyme possesses both phosphoprotamine phosphatase and phosphorylase phosphatase activities. The stimulation of phosphorylase phosphatase activity, but not of phosphoprotamine phosphatase activity, by caffeine and by glucose, suggests that the different activities of this phosphoprotein phosphatase may be regulated separately.

Adenine Nucleotides↗