[Relations between adrenal cortex and adrenal medulla].
Explore the source record for details and available documents.
SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The adrenal cortex of mammals has been known to consist of three morphologically and functionally distinct zones, i.e. the zona glomerulosa (zG), the zona fasciculata (zF) and the zona reticularis (zR), each of which secretes a specific corticosteroid different from those produced by the other two zones. We found previously, however, that an additional zone existed between zG and zF of adult rat adrenal cortex and that the cells in that zone were in a functionally undifferentiated state as an adrenocortical cell [Endocrinology 135, (1994) 431]: they were incapable of synthesizing highly active forms of corticosteroids, such as aldosterone and corticosterone, although they could produce their precursors. Hence, we named the zone as the undifferentiated cell zone (zU) of the adrenal cortex. Here we show that zU and its surroundings, i.e. the innermost portion of zG and the outermost portion of zF are the sites for cell replication in adult rat adrenal cortex and that the cells raised there migrate to other regions. Such cell replications in this region occur regardless of physiological conditions, such as the rise and fall of hormonal stimuli and circadian fluctuation of adrenocortical activities. On the bases of these and other findings previously described, we propose that zU is the stem cell zone of the adult rat adrenal cortex. Our recent success in isolating novel cell lines, which display an undifferentiated phenotype similar to that of zU cells, could facilitate the exploration of molecular mechanisms for the differentiation and development of the adrenocortical cells.
The adrenal cortex is functionally a three-dimensional gland that secretes glucocorticoids, mineralocorticoids, and sex steroids. Of these three classes of steroids only the gluco- and mineralocorticoid hormones are necessary to sustain life. The availability of sensitive and specific radioimmunoassays has permitted accurate measurement of practically every steroid hormone secreted by the adrenal cortex. As in other endocrinopathies, suppression studies are employed when hyperfunction is suspected, while provocative tests are used to detect hypofunction. These dynamic studies enable the clinician to evaluate the functional status of the adrenal cortex. The anatomic configuration of the adrenal cortices is delineated by high-resolution computed tomography (and magnetic resonance imaging), obviating the need for invasive procedures such as venography or arteriography. The disorders of the adrenal cortex can be viewed from the dual perspectives of hyperfunction and hypofunction. Clinical expressions of hyperfunctional adrenocortical syndromes include Cushing's syndrome, primary hyperaldosteronism, and the adrenogenital syndrome. The expressions of hypofunctional syndromes include Addison's disease and selective hypoaldosteronism. The diagnosis and treatment of these disorders are outlined in this issue.
The adrenal cortex is the site of the synthesis of the steroid hormones such as the glucocorticoid cortisol and the mineralocorticoid aldosterone. The pathway of biosynthesis of these steroids from cholesterol involves a sequence of transformations using cytochrome P-450 enzymes. The hypothesis presented here is that damage to cytochrome P-450 enzymes on interaction with certain steroids, synthesized by the adrenal cortex itself, may be of pathological and perhaps physiological importance. The interaction between cytochrome P-450 enzymes and these steroids, which act as pseudosubstrates, may form part of the pathogenesis of some steroidogenic enzyme deficiencies, with consequent overproduction of precursor steroids, leading to mineralocorticoid or androgen excess. This interaction is dependent on achieving high concentrations of the pseudosubstrate steroids in the adrenal cortex, which probably occurs as a result of the arrangement of the vasculature in the adrenal gland. High concentrations of steroids may be expected to accumulate in steroidogenic cells, both in culture and in vivo, and may have autoregulating effects. The high content of antioxidant compounds in the adrenal cortex, principally ascorbate, may serve to protect cytochrome P-450 enzymes from the damaging effects of oxygen radical species formed as a result of cytochrome P-450/pseudosubstrate interactions.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
In vivo models are needed to study the reactions of tissues to DNA damage, such as the induction of the cyclin-dependent kinase inhibitor p21, indicating potential repair of the damage, versus apoptosis, indicating the elimination of the damaged cells. Damage to DNA occurs in tissues during shock, sepsis, and other critical medical conditions. Previous studies have found evidence of damage to the cortex of adrenal glands from organ donors who had undergone severe trauma prior to death. The present experiment studied rats under experimental interventions of clinical relevance to patients with conditions that put them at risk for damage to the adrenal glands. These interventions comprised ischaemia and reperfusion injury, sepsis following caecal ligation and puncture, acute pancreatitis, and administration of chemical agents (zymosan and acrylonitrile). All the interventions caused an increase in p21 mRNA as assessed by northern blotting and in situ hybridization. Increased nuclear p21 protein was shown by immunohistochemistry. All the interventions caused damage to DNA, as shown by labelling of available 3' termini of single-strand breaks with terminal transferase. The number of cells undergoing apoptosis, visualized by ligation of a hairpin oligonucleotide probe to double-strand breaks in DNA, was much lower. In rat adrenal glands, apoptotic cells were infrequent under all the conditions studied. They were more abundant in human organ donor adrenal glands that were previously shown to have extensive DNA damage accompanied by induction of p21. The similarity of the effects of a wide variety of surgical interventions and chemical agents suggest a common pathophysiological mechanism which is not specific to the initiating injury. Experimental injury of the rat adrenal cortex provides a model for investigating the role of organ DNA damage and of mediators of the response to DNA damage, such as p21.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.