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[Morphologic changes in the adrenal cortex in Itsenko-Cushing's syndrome].

Having studied the results of investigation of 132 patients with Icenko-Cushing syndrome (68 out of them with different structural variants of adrenal tumours, 68--without adrenal tumours), the authors came to the conclusion that adenomas of dark and mixed polymorphic cells belong to hormonally active adrenal tumours, while light-cell monomorphic adenomas belong to hormonally inactive tumours. An electron-microscopic study provides identification of signs of functional activity in adenomas and cancer tumours, to clear up the additional criteria of anaplasia in them. In patients with Icenko-Cushing syndrome, but without a tumour in the adrenal cortex ultrastructural changes in corticocytes are characteristic of the increase of cellular proliferation and the decrease of incretory activity. The follow-up results of surgical treatment were studied in all cases.

Adenoma↗

Sexually dimorphic expression of Dax-1 in the adrenal cortex.

BACKGROUND: The DAX-1 (also known as AHC) gene encodes an unusual member of the nuclear receptor superfamily, and the gene product plays a pivotal role during gonadal and adrenal differentiation. Mutations of the human DAX-1 gene cause X-linked adrenal hypoplasia congenita associated with hypogonadotropic hypogonadism. However, the molecular mechanisms underlying the transcriptional regulation of the gene are not well understood. RESULTS: Sexually dimorphic expression of Dax-1 (NR0B1) in the adrenal cortex was observed by RT-PCR, Western blotting and immunohistochemistry. The differential expression was abolished by gonadectomy and was restored again by sex steroid replacement. Our results suggested that the Dax-1 gene transcription is suppressed by androgens and androgen receptor (AR/NR3C4). Dax-1 gene transcription is regulated by Ad4BP/SF-1 (NR5A1), therefore we investigated the functional correlation between A4BP/SF-1 and AR. Interestingly, AR down-regulated the Dax-1 gene transcription mediated by Ad4BP/SF-1 in the presence of the ligand. DNA binding by AR was not essential for the suppressive action, however the suppression seemed to be dependent on the promoter contexts. An interaction between Ad4BP/SF-1 and AR was detected in the presence of the ligand for AR. CONCLUSION: The present study revealed that the expression of Dax-1 in the adrenal cortex is regulated by androgen and the receptor. Interestingly, AR acts as a suppressor in the presence of the ligand through interaction with Ad4BP/SF-1.

Adrenal Cortex↗

Characterisation of heterologous and homologous low-density lipoprotein binding to apolipoprotein B,E receptors on porcine adrenal cortex membranes: enhanced binding of trypsin-modified human low-density lipoprotein.

The characteristics of the binding of homologous and heterologous (human) LDL to membrane preparations from porcine adrenal cortex have been determined. The membranes displayed a single class of high-affinity, saturable binding site for both 125I-labelled porcine and human LDL, which was dependent on divalent cations, in addition to a low-affinity, non-saturable component(s). Porcine LDL displaced both 125I-labelled porcine and 125I-labelled human LDLs from the high-affinity binding site more effectively than human LDL, reflecting the lower Kd, (13.2 micrograms/ml) for porcine than human (Kd 19.2 micrograms/ml) LDL. These values are comparable to those obtained for half-maximal binding of human and bovine LDLs in a bovine adrenocortical membrane system (Kovanen, P.T., Basu, S.K., Goldstein, J.L. and Brown, M.S. (1979) Endocrinology 104, 610-616). Tryptic modification of porcine LDL (T-LDL) diminished its ability to compete with 125I-labelled native LDL for the high-affinity binding site; in contrast, 125I-labelled porcine T-LDL showed an elevated receptor affinity (Kd 9.7 micrograms/ml) and was more efficiently displaced by its unlabelled counterpart than by native porcine LDL. Tryptic treatment of human LDL similarly increased its binding affinity (Kd 8.3 micrograms/ml), although in this case, the unlabelled T-LDL displaced not only 125I-labelled human T-LDL but also 125I-labelled human LDL from the high-affinity site more effectively than native LDL. We conclude that (i) porcine adrenocortical membranes possess binding sites specific for LDL and resembling the apolipoprotein B,E receptors already demonstrated in murine, bovine and human adrenal cortex; (ii) tryptic modification of porcine LDL may remove or destroy segments of apolipoprotein B100 which contribute to receptor recognition sites on the surface of the particle; (iii) trypsinised porcine LDL may interact with the membrane binding site by a mechanism differing from that by which native LDL binds, and (iv) trypsinisation of human LDL may cleave or remove species-specific segments of the B100 protein at or close to the receptor recognition site(s) on the particle, thus decreasing structural differences between porcine and human LDL, and thereby enhancing its binding affinity for the porcine receptor.

Adrenal Cortex↗

[Effect of weightlessness and artificial gravitation on morphological manifestations of the adrenal cortex reaction in rats after space flight on board the biosatellite "Cosmos-936"].

Comparing the changes revealed in the adrenals of rats subjected to weightlessness and artificial gravitation, it has been stated that rotation of the animals in the centrifuge, while flying (with an acceleration of lg), prevents development of morphological stress reaction as a response to landing. After the effect of weightlessness, return to normal gravitation is accompanied with definite signs of an acute stress-reaction in the rat adrenal cortex. Differences in the adrenal reaction of the animals of the groups compared speak in favour of the fact that application of artificial gravitation in an orbital space flight contributes to level the changes resulting from weightlessness and, hence, increase the organism's stability to stress effects, while returning to the Earth.

Adrenal Cortex↗

[Effect of chemical destruction of hypothalamic monoaminergic terminals on function of the adrenal cortex, thyroid gland and enterochromaffin system].

In experiments on rats the influence of noradrenergic, dopaminergic terminal destruction after 6-hydroxydopamine intraventricular injection and of serotoninergic terminal damage following 5,6-hydroxytryptamine administration on the adrenal cortex, thyroid and enterochromaffin body function was studied under basal conditions and during cold stress. As a result of noradrenergic terminal destruction basal- and cold stress-induced functional activity of the adrenal cortex and enterochromaffin body augmented. After serotoninergic terminal damage stress-induced intensification of the functional activity of the endocrine glands mentioned was blocked. The thyroid gland function changed under the hypothalamic noradrenergic and serotoninergic terminal destruction. In the first case a cold-induced rise in the gland functional activity was blocked and in the second one a stress-provoked growth of the thyroid gland activity was rather more than in the control.

Adrenal Cortex↗

[Nycthemeral variations of mitotic activity in the adrenal cortex of the rat].

Working on histologic sections 7 microns thick in the equatorial part of male rat adrenal cortex, we found two high mitotic activity periods. The first one stays at midnight and shows an average number of 42 mitoses per section; the second one occurs at 5 a.m. with an average number of mitoses of 70,1 per section. If we except these particular points, the mitotic activity is low, the average number of mitoses being 13,2 per section.

Adrenal Cortex↗

Ultrastructure of the adrenal cortex in frozen thin sections.

Pieces of both unfixed and fixed rat adrenal cortex were frozen and cut with a cryoultramicrotome. In unstained frozen sections of unfixed adrenals patches of heterochromatin were seen in the nucleus, while numerous round uniformly dense structures, the mitochondria, could be identified in the cytoplasm. Lipid droplets appear as small ligh round areas. Staining the sections with potassium permanganate, phosphotungstic acid, or uranyl acetate, or immersing them in glutaraldehyde, increased the contrast of cell organelles. In frozen sections of fixed material, membranes became visible in negative contrast. Mitochondria display vesicular cristae, whereas the Golgi complex, lysosomes and peroxisomes are easily recognizable. The possibility of cutting frozen sections of unfixed material with reasonable morphological preservation allows the fine-structural localization of steroids in adrenal cells after applying autoradiographic emulsion to the sections.

Adrenal Cortex↗