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PubMed1990

Immunocytochemical localization of the 34 KD pregnenolone-binding protein to fasciculata and reticularis cells and a novel 32 KD protein specific for reticularis cells in guinea pig adrenal cortex.

Two proteins were isolated and purified from guinea pig adrenal cortex: a 34 KD protein that specifically binds pregnenolone (product of the rate-limiting step in steroidogenesis), and a novel co-purifying 32 KD protein that has not been characterized. Specific antisera were generated and used for immunocytochemical analysis. The 34 KD and 32 KD proteins were specific for the adrenal cortex and were absent from other tissues, including the testis. The 34 KD pregnenolone binding protein (PBP) was localized to zona fasciculata and zona reticularis cells and absent from zona glomerulosa cells. Thus, the PBP was absolutely correlated with ACTH-regulated steroidogenic cells, whereas steroidogenic cells regulated by other peptide hormones did not contain the PBP. This finding suggests a functional relationship between the PBP and ACTH. A second interesting finding was that a novel 32 KD co-purifying protein localized to the zona reticularis and was absent from the zona glomerulosa and the zona fasciculata. The 32 KD protein can therefore serve as an excellent marker for the reticularis cell of the adrenal cortex.

Adrenal Cortex↗
PubMed2000

Paracrine control of the adult adrenal cortex vasculature by vascular endothelial growth factor.

The extensive vascular network that irrigates the adult adrenal cortex is essential for both the delivery of oxygen and nutrients to glandular steroidogenic cells and for the rapid and efficient export of corticosteroid products from these cells into the blood flow. During experimental and pathological changes in adrenal cortex size caused by ACTH overproduction or deficiency, the vasculature evolves in a coordinated manner with the mass of glandular cells so that blood vessel formation/regression and cortical gowth/atrophy are respectively synchronized. In addition to its previously reported expression in human fetal adrenocortical cells, the angiogenic factor VEGF-A appears also to be strongly expressed by both glomerulosa and fasciculata cells of the adult bovine adrenal cortex, when the endothelium is quiescent. Moreover, the expression of the two major transcripts encoding the 121 and the 165 amino acid-long isoforms of VEGF-A was observed to be rapidly (within 2-4 h) up-regulated (2-3 fold) by ACTH in primary cultures of bovine fasciculata and glomerulosa cells. The expression of the signalling VEGF receptors R1 (flt-1) and R2 (flk-1) was restricted to the endothelial cells of the cortex whereas neuropilin-1 was expressed by both endothelial and steroidogenic cells. This suggests that, under the control of the pituitary hormone ACTH, VEGF exerts a paracrine control over the vasculature of the adult adrenal cortex. Given its known effects as an anti-apoptotic agent and an inducer of endothelial fenestration, VEGF is likely to play a role in the maintenance of the dense and fenestrated vascular bed of the adrenal cortex. The vasculature thus appears as an important secondary target of ACTH action in the physiological control of adrenal cortex homeostasis.

Adrenal Cortex↗
PubMed1992

Characterization of insulin receptors in the bovine adrenal cortex and medulla.

In order to identify insulin receptors in the bovine adrenal cortex and medulla, we have studied 125I-porcine insulin binding to the membrane preparations from the bovine adrenal cortex and medulla. 125I-porcine insulin bound not only to the bovine adrenal cortex but to the medulla in time-, temperature-, and pH-dependent manners. The maximum levels of 125I-porcine insulin binding in the two tissues were observed at 4 degrees C for 24 h of incubation, and its optimum pH ranged from 7.6 to 8.0. Under these conditions, at tracer concentration of porcine insulin (200 pg/ml), 10.4% and 6.6% of 125I-porcine insulin added to each reaction tube bound specifically to 10(5) x g-pellet fractions (microsomal membrane) from the cortical tissue (0.3 mg of protein) and from the medullary tissue (2 mg of protein), respectively. 125I-porcine insulin binding was observed predominantly in the microsomal membrane from the bovine adrenal cortex, and in a 15,000 x g- pellet fraction (synaptosomal membrane) from the bovine adrenal medulla. Scatchard analysis of binding data yielded curvilinear plots in each tissue. Analysis of curvilinear plots based on two sites model revealed similar affinity constant between the cortex and medulla. Receptor concentration of the cortex was several times higher than that of the medulla. In the two bovine adrenal tissues, human proinsulin and insulin-like growth factor I (IGF-I) had about 1/100 potency compared to porcine insulin in displacing 125I-porcine insulin binding. Porcine glucagon added with concentration up to 10(-6) M did not inhibit 125I-porcine insulin binding to both the cortex and the medulla.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Cortex↗
PubMed2000

Expression of leukemia inhibitory factor (LIF) and LIF receptor (LIF-R) in the human adrenal cortex: implications for steroidogenesis.

It is well established that steroidogenesis in the adrenal cortex is regulated by extraadrenal factors, such as ACTH and angiotensin II. However, over the last years, it has become increasingly clear that paracrine and autocrine mechanisms are also important for steroid synthesis in the adrenal gland. The current study was designed to analyze whether the pleiotropic cytokine leukemia inhibitory factor (LIF) and/or its receptor (LIF-R) are expressed in the normal human adrenal cortex, and whether they may play a role in regulating steroidogenesis. Using LIF- and LIF-R-specific primers, we show by RT-PCR that both mRNAs are expressed in this tissue, as well as in the NCI-H295 adrenal carcinoma cell line. The correct sequences of the PCR products were verified by restriction enzyme analysis and DNA sequencing. Immunohistochemistry, employing specific antibodies against LIF and LIF-R, reveals expression of both proteins in the normal human adrenal cortex. Finally, we show that LIF can significantly enhance basal and ACTH-induced production of cortisol and aldosterone in NCI-H295 cells. In summary, we show for the first time that LIF and its receptor are expressed in the normal human adrenal cortex. Our stimulation experiments indicate that the intraadrenal LIF/LIF-R system may participate in regulating adrenal steroidogenesis.

Adrenal Cortex↗
PubMed1979

Pilocarpine and atropine effects on the mitotic activity of the adrenal cortex.

Because of the postulated presence of direct nervous cholinergic connections between the adrenal cortex and the hypothalamic centers, effects of pilocarpine and atropine on the adrenal cortex mitotic activity were examined. The obtained results show that pilocarpine stimulates and atropine inhibits the proliferation of cells in zona glomerulosa and zona fasciculata of the adrenal cortex. It seems that the stimulating effect of pilocarpine may be related to the muscarinic receptor activation on the level of the cholinergic nervous terminals in the adrenal cortex.

Adrenal Cortex↗
PubMed1980

Development of the adrenal cortex in the fetal sheep: an ultrastructural study.

The adrenal cortex from 31 fetal lambs ranging from 60 to 146 days of gestation was examined by light and electron microscopy. The adrenals of two newborn lambs and three adult ewes were also examined. The adrenal cortex of the adult gland is divided into three regions. The cortex of the fetal lamb consists of two regions only for no zona reticularis is ever clearly seen. The adrenal cortex grows steadily throughout gestation until a rapid phase of growth in the final few days. Most of this terminal growth takes place in the zona fasciculata; it coincides with the known sharp rise in fetal plasma corticosteroids. The cells of the zona glomerulosa appeared capable of secreting steroids in the earliest fetus examined. The cells changed little throughout gestation but from 116 days to term there was an obvious alteration in the proportion of tubular to lamellar cristae within the mitochondria. Cells within the zona fasciculata appeared to undergo functional differentiation as gestation progressed. At 60 days only a few cells appeared capable of secreting steroids. These were situated at the cortico-medullary border and contained mitochondria with mainly vesicular but some tubulolamellar cristae, smooth endoplasmic reticulum and large Golgi apparatus. The remainder of the cells within the region contained mitochondria with tubulolamellar cristae and smaller amounts of predominantly rough endoplasmic reticulum. As gestation progressed the number of differentiated cells increased slowly and in a radial direction towards the zona glomerulosa. As the cells differentiated the amount of endoplasmic reticulum increased and changed from mainly rough to predominantly smooth profiles. The mitochondrial cristae became mainly vesicular. These changes appear to relate to an increase in steroidogenic capacity of the cells. There is a rapid development of functionally differentiated zona fasciculata cells in the last few days of gestation.

Adrenal Cortex↗
PubMed1983

In vitro synthesis of NADPH-adrenodoxin reductase and adrenodoxin of bovine adrenal cortex, and the existence of a large precursor of adrenodoxin.

Cytoplasmic free and bound polysomes isolated from bovine adrenal cortex were used to program protein synthesis in rat liver cell sap (175,000 X g soluble material) and wheat germ lysate S-175 (175,000 X g soluble material) systems. Both free and bound polysomes were translated with high fidelity and equal efficiency in the cell-free systems. Synthesis of adrenodoxin reductase (AdR) and adrenodoxin (Ad) in the cell-free systems was determined by the immunoprecipitation of the translation products using monospecific antibodies, and we found that AdR was synthesized by free polysomes whereas Ad was synthesized by both free and bound polysomes as a large precursor (pAd) having a molecular weight of approximately 22,000 daltons, which is about 10,000 daltons larger than mature Ad. The existence of a large precursor of Ad was also confirmed by its synthesis in a cell-free system programmed by total RNA isolated from bovine adrenal cortex. Bovine adrenal cortex mitochondria imported in vitro-synthesized AdR and pAd to the inside of the organelle in the absence of protein synthesis in a cell-free system, and processed pAd to the mature form during the import. These results suggest that cytoplasmically synthesized AdR and Ad are translocated posttranslationally into the matrix of mitochondria in adrenal cortex cells.

Adrenal Cortex↗
PubMed1980

[Histological changes in the adrenal cortex of the Syrian hamster following perinatal treatment with sex steroids].

The adrenal cortex of the Syrian golden hamster is influenced by androgen hormone, for during puberty sex dimorphism of the adrenal cortex can be observed; it is prevented by perinatal castration. The following study will show, if and how other steroids influence the adrenal cortex of the normal and castrated female and male golden hamster. Beginning perinatally, groups of 10 hamsters each (intact and castrated males and females, altogether 160 animals) received testosterone hexohydrobenzoate (T), oestrogen undecylate (0), cyproterone acetate (CA) or sesame oil till the 6th week of life in an increasing, from the 6th-12th week in a constant dose. (T: 2.0 mg, 0: 1.0 mg, CA: 10.0 mg/week). The animals were sacrificed at the end of the 12th week of life. Control of adrenal weight; light microscopy of the adrenals; histometry, statistical evaluation of all data, and histochemistry. The adrenals of intact and castrated animals reacted in the same way. Under T treatment, in females, the zona reticularis enlarged as in males. By light microscopy and histometry there were no differences anymore between the female and male adrenals. 0 feminized the adrenal of the male, i.e. the zona reticularis became narrow with small cells, while the adrenal cortex of the female did not change. In both sexes, CA affected the zona reticularis less than the zona fasciculata. Thereby numeric and single cell atrophy was caused. Our results demonstrate the sex-specificity of the zona reticularis, showing a contrary influence by T and 0, and the rather glucocorticoid than anti-androgen-like effect by CA upon the adrenals.

Adrenal Cortex↗
PubMed2000

The involvement of prolactin in the regulation of adrenal cortex function in pigs.

We investigated the in vivo and in vitro effect of prolactin (PRL) on porcine adrenal cortex function. The in vivo study was performed on 10 multiparous sows. Blood was sampled every 4 h beginning on the 17th day of the estrous cycle and continuing for 6 subsequent days. Plasma was stored at -20 degrees C until steroid hormones analysis was completed. PRL or saline were administered iv for 48 h in 2 h intervals. Injections of PRL began 4-20 h after the preovulatory LH surge. At the end of the sampling period sows were slaughtered and adrenals were immediately dissected. Adrenals were frozen at -70 degrees C for determination of adrenal cortex steroid hormones content. At the end of PRL treatment period mean plasma level of cortisol in control sows was significantly lower than that of PRL-treated sows. Moreover, the area under the mean plasma cortisol concentration curve was significantly higher in PRL-treated sows in comparison to controls. The mean cortisol adrenal content was significantly higher in adrenal cortex of PRL-treated sows than that of controls. PRL did not affect adrenal cortex concentration of androstenedione (A(4)), testosterone (T), dehydroepiandrosterone (DHEA) and estradiol (E(2)). Dehydroepiandrosterone sulfate (DHEAS) was not found in porcine adrenal cortex. In the in vitro experiment adrenal glands were removed immediately after slaughter of 6 crossbred gilts. Dispersed adrenocortical cells were incubated for 8 h with or without porcine PRL. Prolactin stimulated cortisol secretion in a dose-dependent manner. These results suggest that PRL is one of the key factors involved in the regulation of adrenal cortex function in pigs.

Adrenal Cortex↗