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Results for “ADRENAL CORTEX”

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At least 1,585 records · Page 88Linked to original sources
PubMed1997

Novel environment induced inhibition of corticosterone secretion: physiological evidence for a suprachiasmatic nucleus mediated neuronal hypothalamo-adrenal cortex pathway.

Basal plasma ACTH and corticosterone levels are controlled by the suprachiasmatic nucleus (SCN), the site of the circadian pacemaker, resulting in a daily peak in plasma corticosterone and ACTH. The present study was carried out to investigate the mechanisms employed by the biological clock to control these hormones. Novel environment induced changes in plasma ACTH and corticosterone in intact and SCN-lesioned animals were employed as experimental approach. Placing intact animals in a new environment results in different plasma corticosterone and ACTH responses depending on the clock time of the stimulus. (1) Novel environment (2 h after onset of darkness (ZT14)) results in a fast decrease followed by an increase in corticosterone. This changing pattern in corticosterone secretion was not accompanied by any change in plasma ACTH, suggesting a direct neuronal control of the adrenal cortex. (2) In contrast, novel environment at 2 h after light onset (ZT2) results in a rapid increase in plasma ACTH. Regression analysis of the relation ACTH-corticosterone before and after stress shows a changed pattern at ZT2, although at that time still no significant correlation between ACTH and corticosterone was detected. AT ZT14 this correlation was only present after stress. (3) SCN lesioning results in low basal ACTH at all circadian times combined with elevated corticosterone levels. Here, a new environment results in an immediate increase in corticosterone without inhibition; ACTH also increases rapidly, but attains lower levels than at ZT2 in intact animals. (4) The present results therefore demonstrate SCN modulating corticosterone secretion by affecting ACTH secretion and changing the sensitivity of the adrenal cortex by means of a neuronal input.

Adrenal Cortex↗
PubMedDate not supplied

Limbic system-adrenal cortex regulation in depression and schizophrenia.

Hypothalamo-pituitary-adrenal [HPA] activation and abnormal HPA regulatory mechanisms have been observed in depressed patients. Depressed and schizophrenic patients were studied to determine whether the HPA disturbances in depression are specific to this psychiatric illness or are mediated by nonspecific breakdown of psychological defense mechanisms. Despite the presence of severe ego defense breakdown and considerable secondary depressive symptomatology, the schizophrenic patients had normal HPA function. The depressed patients had elevated urine free cortisol excretion, high CSF cortisol levels, and did not show normal HPA suppression in response to dexamethasone. Within the depressed group significant correlations of HPA parameters were obtained with somatic features but not with ego breakdown features. After recovery depressed patients had more normal HPA function. The results indicate that HPA dysfunction can occur in association with primary depressive illness, that a psychoendocrine distinction can be made between primary depressive illness and secondary depressive symptomatology, and that psychological defense breakdown is not related to these neuroendocrine observations. Attention is drawn to the utility of urinary free cortisol measurement as a valuable index of HPA activation in psychoendocrine studies.

Adolescent↗
PubMed1975

Steroid hydroxylations by human adrenal cortex microsomes 1, 2.

Microsomes were prepared from human adrenals obtained at the time of cadaveric renal transplantation. Microsomes were assayed for cytochrome P-450 concentrations (mean =0.63 nmol/mg protein) and NADPH-cytochrome c reductase activity (mean 65 nmol times min-1 times mg-1 protein). Rates of steroid hydroxylation were measured. In man, the rate of 21-hydroxylation of 17-hydroxyprogesterone was approximately three times the rate of 21-hydroxylation of progesterone. The rate of 17-hydroxylation of progesterone was approximately three times the rate of 21-hydroxylation of progesterone. Substrate binding to microsomes showed a type I spectrum with progesterone and 17-hydroxy-progesterone. Both substrates bound all spectrally identifiable sites. Antibody prepared against procine NADPH-cytochrome c reductase inhibited concomitantly human reductase, 21-hydroxylation of progesterone and 17-hydroxyprogesterone, and 17-hydroxylation of progesterone. These results were compared to previous studies with beef adrenal microsomes. No specific evidence was obtained to suggest multiple forms of 21-hydroxylase in human adrenal microsomes. It appears as though the human adrenal microsomal cytochrome P-450 electron transport chain is immunologically similar to those studied previously--beef adrenal, and rat and human liver.

Adrenal Cortex↗
PubMedDate not supplied

[Role of the anterior pituitary gland in the regulation of 18-hydroxydesoxycorticosterone by the adrenal cortex].

The work is devoted to a study of the hypophysis control of the adrenal cortex hormone--18-hydroxy-11-deoxycorticosterone (18-HO-DOC) secretion; these investigations were performed on 136 mongrel female rats, weighing 130-140 g. The regulating role of the hypophysis on the 18-HO-DOC secretion was ascertained on the hypophysectomized animals (pseudohypophysectomized animals served as control) and intact rats to which ACTH was administered (physiological saline was injected to control animals). The rate of secretion, specific rate of secretion, and the secretion content in the blood and in the arenal efferent and the peripheral vessels were determined by thin-layer chromatography and competitive protein binding. The data obtained led to the conclusion that both corticosterone and 18-HO-DOC were regulated by the hypophysis. Under the effect of stress there apparently occurred selective regulating action of ACTH on 18-HO-DOC and corticosterone secretion indicating that the expediency of elevation of one or another steroid secretion was determined by the character of stress reaction, the blood adrenocorticotropin and corticosteroid level.

18-Hydroxydesoxycorticosterone↗
PubMed1979

Molecular properties of cytochrome P-45011 beta from adrenal cortex mitochondria.

Cytochrome P-45011 beta has been solubilized and partially purified from bovine adrenal cortex mitochondria using chromatography on Octyl-Sepharose CL-4B or DEAE-Sepharose CL-6B. The partially purified P-450 preparations were about 90% pure as judged by SDS-polyacrylamide gel electrophoresis. In the presence of purified preparations of adrenodoxin reductase and adrenodoxin, the partially purified P-450 preparations catalyzed NADPH-supported 11 beta-hydroxylation of unconjugated and sulphoconjugated deoxycorticosterone. In presence of Triton X-100 the partially purified cytochrome P-45011 beta had a Stoke's radius of 4.5 nm, a sedimentation coefficient of 3.1 S and a partial specific volume of about 0.85 cm3/g. These results indicate that the cytochrome P-45011 beta-Triton X-100 complex has a molecular weight of about 100 000 and that P-45011 beta bound about 1.1 g of Triton X-100 per g of protein. The P-45011 beta-Triton X-100 complex was catalytically active in hydroxylation reactions supported by NADPH or the hydroxylating agent ortho-nitroiodosobenzene, suggesting that the monomer of cytochrome P-45011 beta is an active form of the protein.

Adrenal Cortex↗
PubMed1976

Crystalloid configuration in the adrenal cortex of the Siamese tree shrew (Tupaia glis).

Crystalloids of what appear to be smooth reticulum have been observed in the zona fasciculata and zona reticularis in both the stressed and nonstressed adrenal gland of the Siamese tree shrew (Tupaia glis). No crystalloids are observed in the zona glomerulosa. Similar crystalloids have been described in other steroid-secreting organs, including the antebrachial organ of the lemur (Lemur catta), the parotoid gland of Bufo alvarius and in sebaceous gland cells of the Galagos and Macaques. Moreover, the crystalloids in the present investigation resemble the paracrystalline arrays of smooth reticulum present in the adrenal cortex of the fetal guinea pig. The crystalloids show much variation in degree of organization, sometimes appearing as wavy tubules parallel with one another or as fused tubules having a "donut" configuration. In addition, the crystalloids are nearly identical to configurations which have been described in mitochondrial cristae of the protozoan, Pelomyxa carolinensis.

Adrenal Cortex↗
PubMed1978

The active form of cytochrome P-45011beta from adrenal cortex mitochondria.

Cytochrome P-45011beta has been solubilized and partially purified from bovine adrenal cortex mitochondria by means of chromatography on Octyl-Sepharose CL-4B or DEAE-Sepharose CL-6B. The partially purified P-450 preparations were about 90% pure as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but had a low specific content of P-450 (between 1 and 2 nmol of P-450 per mg of protein). In the presence of purified preparations of adrenodoxin reductase and adrenodoxin, the partially purified P-450 preparations catalyzed NADPH-supported 11beta-hydroxylation of unconjugated and sulfoconjugated deoxycorticosterone. In the reconstituted system the hydroxylation of deoxycorticosterone sulfate proceeded at a much higher rate than in intact mitochondria, indicating that in the former case interactions between the hydrophilic substrate and P-450 were facilitated. In the presence of Triton X-100 the partially purified cytochrome P-45011beta had a Stokes radius of 4.5 nm, a sedimentation coefficient of 3.1 S, and a partial specific volume of about 0.85 cm3/g. These results indicate that the cytochrome P-45011beta . Triton X-100 complex had a molecular weight of about 100,000 and that P-45011beta bound about 1.1 g of Triton X-100 per g of protein. The P-45011beta . Triton X-100 complex was catalytically active in hydroxylation reactions supported by NADPH or the hydroxylating agent ortho-nitroiodosobenzene, suggesting that the monomer of cytochrome P-45011beta is the active form of the protein.

Adrenal Cortex↗