PubMed Health⌕ Search

Biomedical subjects

C Robba

Publications and source records attributed to C Robba.

At least 37 records · Page 2Linked to original sources
PubMed1986

Long-term trophic action of alpha-melanocyte-stimulating hormone on the zona glomerulosa of the rat adrenal cortex.

The effects of alpha-melanocyte-stimulating hormone (alpha-MSH) on the rat adrenal cortex were investigated by coupled morphometric and radioimmunological techniques. Short-term alpha-MSH administration provoked a significant increase in the aldosterone plasma level along with a notable lipid droplet depletion in zona glomerulosa cells. Long-term alpha-MSH treatment induced a notable hypertrophy of zona glomerulosa cells and a further rise in the blood concentration of aldosterone. alpha-MSH did not affect zona fasciculata morphology and corticosterone plasma level. The possibility is discussed that alpha-MSH may be specifically involved in the control of the growth and steroidogenic capacity of rat adrenal zona glomerulosa.

Adrenal Cortex↗
PubMed1986

Effects of the hypolipidemic drug nafenopin on the zona glomerulosa of the rat adrenal cortex: morphological counterparts of functional alterations.

The effects of nafenopin, a hypolipidemic drug, on the zona glomerulosa of the rat adrenal cortex were investigated. Chronic nafenopin treatment significantly lowered serum cholesterol level, but did not alter blood aldosterone concentration, though the biosynthesis of adrenal cortico-steroid hormones seems to be largely dependent upon a continuous uptake of cholesterol from plasma lipoproteins. Stereology showed that the treatment provoked a notable lipid droplet depletion, coupled with a significant proliferation of smooth endoplasmic reticulum (SER) profiles. Since SER is known to be involved in the endogenous synthesis of cholesterol, the hypothesis is advanced that SER hypertrophy is a compensatory response enabling zona glomerulosa cells to maintain an adequate level of aldosterone output even in the absence of a normal supply of exogenous cholesterol.

Adrenal Cortex↗
PubMed1986

Long term effects of the hypocholesterolaemic drug 4-aminopyrazolo-pyrimidine on the zona fasciculata of the rat adrenal cortex.

Prolonged 4-APP administration to dexamethasone/ACTH-treated rats was found to lower both plasma and intra-adrenal gland cholesterol concentrations. Morphological examination showed that zona fasciculata cells underwent a severe lipid droplet depletion, and a conspicuous increase of agranular endoplasmic reticulum and peroxisomes. The blood level of corticosterone remained unchanged. A high cholesterol diet completely reversed the effects of 4-APP treatment. The hypothesis is discussed that these morphological changes are the expression of a compensatory response enabling rat adrenocortical cells to maintain an adequate level of hormone output even in the absence of a normal supply of exogenous cholesterol.

Adenine↗
PubMed1985

Effect of somatostatin on the zona glomerulosa of rats treated with angiotensin II or captopril: stereology and plasma hormone concentrations.

Chronic somatostatin (SRIF) administration induced atrophy of zona glomerulosa cells of the rat adrenal cortex and a noticeable fall in the plasma concentration of aldosterone. The effects of SRIF were comparable with those of captopril, a specific inhibitor of the angiotensin-converting enzyme. SRIF completely abrogated the adrenoglomerulotrophic effects of angiotensin II (AII); the inhibitory actions of SRIF and captopril were not additive. The slight but significant enhancement of zona fasciculata cell growth and plasma corticosterone levels caused by chronic AII administration were ot reversed by SRIF. We interpret these data to indicate that SRIF specifically modulates the stimulatory effects of AII on the growth and steroidogenic capacity of rat zona glomerulosa.

Adrenal Cortex↗
PubMed1985

Trophic effects of potassium loading on the rat zona glomerulosa: permissive role of ACTH and angiotensin II.

The trophic effects of chronic potassium loading on the rat zona glomerulosa were investigated by morphometric and radioimmunological methods. Potassium loading exerted a potent adrenoglomerulotrophic effect in saline treated control rats, but it was not able to reverse the captopril- and dexamethasone-induced atrophy of the zona glomerulosa. However, if the captopril/dexamethasone administered rats were given maintenance doses of angiotensin II and ACTH, potassium loading was found to exert a strong trophic action. The hypothesis is advanced that potassium loading requires the integrity of both the renin-angiotensin system and the hypothalamo-hypophyseal axis to exert its powerful direct stimulating effect on the growth and steroidogenic capacity of the rat zona glomerulosa.

Adrenal Glands↗
PubMed1985

Opposed effects of chronic prolactin administration on the zona fasciculata and zona reticularis of the rat adrenal cortex: an ultrastructural stereological study.

The effects of a prolonged treatment with prolactin on the morphology and hormone secretion of rat adrenal zona fasciculata and zona reticularis, were investigated by coupled morphometric and radio-immunological techniques. Chronic prolactin administration provoked a notable atrophy of zona fasciculata cells and a small but significant increase in the corticosterone plasma level, which can be the result of the prolactin-induced inhibition of the intra-adrenal 5 alpha-reductase. Therefore, the atrophy of the zona fasciculata may be reasonably supposed to be not a direct effect of prolactin, but indirectly caused by a negative feed-back mechanism blocking ACTH release. On the contrary, prolonged prolactin treatment induced a conspicuous hypertrophy of zona reticularis cells, as well as a notable rise in the plasma concentration of testosterone, which cannot be due to gonad stimulation by prolactin since orchiectomized rats were employed. As the zona reticularis, like zona fasciculata, is ACTH-dependent, it must be concluded that prolactin exerts a direct stimulating effect on the growth of the zona reticularis, whose functional counterpart conceivably is an enhanced production of androgen hormones.

Adrenal Cortex↗
PubMed1984

Inhibitory effect of somatostatin on the growth and steroidogenic capacity of rat adrenal zona glomerulosa.

Chronic administration of somatostatin induced atrophy of zona glomerulosa cells of rat adrenals and lowering of plasma aldosterone concentration. Zona fasciculata cells did not display any significant change and corticosterone plasma concentration was not significantly affected. These findings are interpreted to indicate that somatostatin exerts a direct inhibitory effect on the growth and steroidogenic capacity of rat adrenal zona glomerulosa.

Adrenal Cortex Hormones↗
PubMed1984

Effects of ACTH on adrenocortical cells autotransplanted in the rat spleen: ultrastructural and morphometric observations.

The effects of chronic ACTH administration on adrenocortical cells autotransplanted in the rat spleen have been investigated. Morphometry showed that ACTH induced a significant hypertrophy of adrenocortical cells, which was mainly due to the increase in the smooth endoplasmic reticulum and mitochondrial compartment. Competitive protein binding assay demonstrated that adrenocortical cell hypertrophy was associated with a two-fold rise in the plasma corticosterone concentration. These data indicate that autotransplanted adrenocortical cells are normally sensitive to ACTH, which enhances their growth and steroidogenic capacity.

Adrenal Cortex↗
PubMed1983

Morphometric investigations into the mechanism of the compensatory hypertrophy of the rat adrenal zona fasciculata after unilateral adrenalectomy.

Compensatory hypertrophy of the remaining gland in unilaterally adrenalectomized rats was investigated by morphometric techniques. It was observed that compensatory adrenal growth occurred in both dexamethasone-treated and hypophysectomized rats, receiving maintenance doses of ACTH. However, it was only half that found in intact animals. These results support the view that activation of the hypothalamo-hypophyseal axis is not the unique mechanism underlying adrenal compensatory hypertrophy in the rat.

Adrenal Glands↗
PubMed1983

Effects of testosterone on the zona fasciculata of the male rat adrenal cortex. A correlated stereological and biochemical study.

The effects of long-term testosterone administration on the adrenal cortex of male rats were investigated by coupled morphometric and biochemical methods. Morphometry showed that testosterone treatment provoked a time-dependent atrophy of the zona fasciculata cells, which was mainly due to the decrease in the volume of the mitochondrial compartment and smooth endoplasmic reticulum (SER). Biochemical assays demonstrated that the decrease in the surface area per cell of SER membranes and mitochondrial cristae was tightly paralleled by the decrease in the activity per cell of two key enzymes of steroid synthesis contained in them (delta 5-3 beta-hydroxysteroid dehydrogenase and 11 beta-hydroxylase). The testosterone-induced inhibition of the growth maintenance and steroidogenic capacity of adrenocortical cells provoked a significant fall in the plasma concentration of corticosterone and a consequential increase in the level of circulating ACTH. Chronic administration of testosterone caused a notable suppression of the activity of the adrenal 5 alpha-reductase and this in turn provoked a rise in the intracellular concentration of corticosterone. Moreover, testosterone inhibited the incorporation of 3H-uridine into the nuclear and mitochondrial fractions of male rat adrenocortical cells. These findings exclude the possibility that the testosterone-provoked atrophy of the male rat adrenal glands is mediated by the suppression of the hypothalamo-hypophyseal axis, and suggest that the mechanism underlying this action of testosterone involves inhibition of nuclear and mitochondrial RNA synthesis. Whether this effect of testosterone is directly or indirectly mediated by the rise in the intracellular content of corticosterone due to the inhibition of 5 alpha-reductase activity, remains to be elucidated.

3-Hydroxysteroid Dehydrogenases↗
PubMed1982

Effects of the hypolipidemic drug nafenopin on the zona fasciculata of the rat adrenal cortex: a correlated biochemical and stereological study.

The effects of Nafenopin, a hypolipidemic drug, on the zona fasciculata of the rat adrenal cortex were investigated by biochemical, stereological, and cytochemical methods. Chronic Nafenopin treatment (5 days) significantly lowered serum cholesterol level, while it did not alter blood corticosterone concentration and 11beta-hydroxylase activity of adrenocortical cells. Stereology showed a significant increase in the average volume of zona fasciculata cells, which was almost exclusively due to smooth endoplasmic reticulum (SER) proliferation. The volume of lipid compartment was significantly reduced, whereas the volume of diaminobenzidine (DAB)-positive bodies (peroxisomes) per cell displayed a marked increase. Cholesterol administration per os to the treated animals raised the serum cholesterol level and completely reversed the Nafenopin effects. One day of Nafenopin administration provoked a slight but significant lipid depletion in adrenocortical cells, while 3 days of continuous drug treatment induced an extreme lipid depletion and a moderate increase in the SER coupled with a significant decrease in the plasma concentration of corticosterone. Since microsomal fraction and catalase seem to be involved in the cholesterol metabolism and utilization, the hypothesis is advanced that the Nafenopin-elicited SER and peroxisome proliferation is a compensatory response enabling adrenocortical cells to maintain an adequate level of hormonal output.

Adrenal Cortex↗
PubMed1982

An electron-microscopic stereological study of the compensatory hypertrophy of the rat adrenal zona fasciculata after unilateral adrenalectomy.

The ultrastructural changes associated with the compensatory hypertrophy of the zona fasciculata cells on monoadrenalectomized rats were investigated by stereological techniques. It was found that these subcellular changes display a different pattern from those underlying the ACTH-induced adrenocortical cell growth in the intact rats. This result supports the view that compensatory adrenal hypertrophy does not involve activation of the hypothalamo-hypophyseal-adrenal axis.

Adrenal Cortex↗
PubMed1982

Effects of a chronic treatment with testosterone on the morphology of the interstitial cells of the rat testis: an ultrastructural stereologic study.

The suppressive effects of chronic testosterone administration on the rat testicular interstitial cells (Leydig cells) were investigated by stereological methods. The volume of cells, nuclei, mitochondrial compartment and smooth endoplasmic reticulum (SER), as well as the surface area of SER and mitochondrial cristae decreased significantly as a function of the duration of treatment. The decrease in the SER volume accounted for about 75-80% of that in the cell volume. These findings lend support to the view that SER is the subcellular organelle more responsive to the changes in the functional activity of rat Leydig cells.

Animals↗
PubMed1982

Effects of ACTH on the zona glomerulosa of sodium-loaded timolol maleate-treated rats: stereology and plasma hormone concentrations.

The effect of chronic ACTH administration on the growth and aldosterone secretion of the zona glomerulosa of sodium-loaded timolol maleate-treated rats was investigated by stereological and radioimmunological techniques. Combined sodium loading and timolol maleate administration induced a significant atrophy of the zona glomerulosa and its cells. The plasma concentration of aldosterone was significantly decreased, while that of corticosterone did not vary. ACTH administration completely reversed zona glomerulosa atrophy, and the plasma concentration of corticosterone was noticeably enhanced, whereas that of aldosterone underwent a further decrease. This data suggests that in the absence of the other adrenoglomerulotrophic factors, ACTH stimulates the growth of the zona glomerulosa, but transforms its parenchymal elements to a functional fasciculata cell type.

Adrenal Glands↗
PubMed1982

Effects of sodium repletion and timolol maleate administration on the zona glomerulosa of the rat adrenal cortex: an electron microscopic morphometric study.

The effects of long-term sodium repletion and timolol maleate treatment on the zona glomerulosa of dexamethasone- and ACTH-administered rats were investigated. Morphometry showed that both treatments induced a noticeable atrophy of the zona glomerulosa and its parenchymal cells, which is mainly due to the decrease in the smooth endoplasmic reticulum and the mitochondrial compartment. Radio-immunological studies indicated that in the treated rats the plasma aldosterone concentration was significantly decreased. Combined sodium repletion and timolol maleate administration provoked more intense effects than the single treatments. These data confirm the contention that both Na/K balance and the renin-angiotensin system are involved in the maintenance of the growth and steroidogenic capacity of the rat zona glomerulosa, with interfering without the hypothalamo-hypophyseal-adrenal axis.

Adrenal Cortex↗
PubMed1982

Ultrastructure of aldosterone secreting adrenal adenomata.

Two adrenocortical adenomata causing Conn's syndrome were examined by electron microscopy. Adenomatous cells were arranged in small clusters and showed a rather different morphology, especially as far as mitochondria were concerned. Some cells contained mitochondria with lamellar and tubular cristae (zone glomerulosa-like cells), while other parenchymal elements displayed mitochondria with tubular and vesicular cristae (zona fasciculata-like cells). Both cells types were endowed with a quite well developed smooth endoplasmic reticulum, some lipid droplets and a prominent Golgi apparatus. Moreover, adenomatous cells with large masses of lipofuscin pigment granules were also observed (zona reticularis-like cells). These findings stress the structural heterogeneity of the Conn's adenomata.

Adenoma↗
PubMed1982

Ultrastructural observations on the regeneration of adrenocortical autotransplants in the rat spleen.

The regeneration of adrenocortical autotransplants in the rat spleen has been investigated by light and electron microscopy. Up to the seventh day after implantation, adrenal grafts showed large areas of necrosis and contained many degenerating (apoptotic) adrenocortical cells, some mesenchyme-like poorly differentiated elements, and occasional viable parenchymal cells. These last cells possessed mitochondria with scanty tubular cristae and few profiles of smooth endoplasmic reticulum. After 15 days of regeneration, adrenal grafts were reduced in volume, but contained only viable adrenocortical cells; after 30-36 days, autotransplants were noticeably enlarged and surrounded by an evident connective tissue capsule. Regeneration was closely associated with the morphological differentiation of adrenocortical cells, which one month after transplantation were found to assume all the typical features of adult rat zona fasciculata elements (i.e. mitochondria with vesicular cristae, abundant smooth endoplasmic reticulum, some lipid droplets and a well developed Golgi apparatus).

Adrenal Cortex↗