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P Rebuffat

Publications and source records attributed to P Rebuffat.

At least 109 records · Page 6Linked to original sources
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

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↗
PubMed1981

Investigations on the turnover of adrenocortical mitochondria. XVII. A correlated stereological and autoradiographic study of the effects of chronic treatment with ethidium bromide on the growth of the rat zona reticularis mitochondria.

The effects of the prolonged administration of ethidium bromide (EB), at a dose provoking a persistent inhibition of the incorporation of 3H-thymidine and 3H-uridine into the mitochondrial fraction, on the zona reticularis of ACTH-treated rats were investigated. Stereologically, it was found that EB induces noticeable decrease in the total amount of the mitochondrial compartment, mainly due to the reduction in the number of organelles per cell. High resolution autoradiography showed that the mechanism underlying this effects of EB probably involves both the inhibition of mitochondria proliferation and the acceleration of their breakdown as "intact units". These findings suggest that the ACTH-induced maintenance of the zona reticularis mitochondria growth involves mitochondrial DNA reduplication and transcription.

Adrenal Cortex↗
PubMed1981

Effects of angiotensin II on the zona fasciculata of the rat adrenal cortex: an ultrastructural stereologic study.

The effects of a chronic administration of angiotensin II on the zona fasciculata of rats treated with dexamethasone and maintenance doses of ACTH were investigated by morphometric methods applied to electron microscopy. It was found that angiotensin induced a significant increase in the volume of cells, nuclei, mitochondrial and lipid compartments as well as in the surface area of smooth endoplasmic reticulum and mitochondrial cristae. Noticeable also were the hypertrophy of the Golgi apparatus and the increase in the number of acid phosphatase-positive dense bodies. These findings are interpreted as indicating that the renin-angiotensin system is involved in the stimulation of the growth and steroidogenic capacity of the rat zona fasciculata.

Adrenal Cortex↗
PubMed1980

Investigations on the turnover of adrenocortical mitochondria. XIV. A correlated biochemical and stereological study of the effects of chronic treatment with ethidium bromide on the growth maintenance of the rat zona fasciculata mitochondria.

The effects of ethidium bromide (EB) on rat adrenocortical cells were investigated by biochemical and stereological methods. It was found that a treatment with ip. injections of 10 microgram/gm of EB every 12 hours induced a persistent inhibition of the incorporation of 3H-thymidine and 3H-uridine into the mitochondrial fraction, but not into the nuclear fraction. Chronic treatment with this dose of EB provoked in zona fasciculata cells of rats treated with maintenance doses of ACTH a noticeable decrease in the volume of the mitochondrial compartment (due to the decrease both in the number per cell and in the average volume of the organelles) and in the surface area of the mitochondrial cristae. These findings lend support to the hypothesis that the mechanism underlying the ACTH-induced maintenance of the growth of adrenocortical mitochondria involves mitochondrial DNA reduplication and transcription.

Adrenal Cortex↗
PubMed1980

Investigations on the turnover of adrenocortical mitochondria. XV. A stereological study of the effect of chronic treatment with angiotensin II on the size and number of the mitochondria in the zona glomerulosa of the rat.

The effects of a chronic treatment with angiotensin II (up to 15 consecutive days) on the mitochondria of the rat zona glomerulosa cells were investigated by electron microscopic and stereological methods. Angiotensin induced a significant increase in the volume of the mitochondrial compartment. Up to the 3rd day of treatment this was due only to the hypertrophy of the organelles, and from the 3rd to the 15th day exclusively to mitochondrial proliferation. The hypothesis that angiotensin controls the growth and proliferation of rat zona glomerulosa mitochondria is discussed.

Adrenal Cortex↗
PubMed1980

Effects of human chorionic gonadotropins on the interstitial cells of the rat testis: A morphometric and radioimmunological study.

The effects of human chorionic gonadotropins (hCG) on the rat testicular interstitial cells (Leydig cells) were investigated by stereologic and radio-immunological methods. Short-term (2 h's) hCG-administration induced only lipid depletion in the Leydig cells. Chronic hCG-treatment provoked a significant cell hypertrophy, which was mainly due to smooth endoplasmic reticulum proliferation; the surface area of mitochondrial cristae, and the volume of the lipid and peroxisome compartments were also significantly increased. These morphologic findings are discussed in the light of radioimmunological data, showing that chronic hCG-administration increased the steroidogenic capacity (testosterone output) of the Leydig cells.

Animals↗
PubMed1980

An ultrastructural stereologic study of the effects of angiotensin II on the zona glomerulosa of rat adrenal cortex.

The effects of angiotensin II on the rat zona glomerulosa were investigated by morphometric and radio-immunological methods. Short-term (1 h) angiotensin-administration induced lipid depletion in zona glomerulosa cells and a significant rise in the plasma aldosterone concentration. Chronic angiotensin-treatment provoked a noticeable increase in the volume of the zona glomerulosa and its cells, which was mainly due to the hypertrophy of smooth endoplasmic reticulum and mitochondrial compartment. In chronically treated animals the output of aldosterone in response to a short-term stimulation with angiotensin II displayed a significant increase. These findings are interpreted as indicating that angiotensin II is involved in the stimulation of the growth and steroidogenic capacity of the rat zona glomerulosa.

Adrenal Cortex↗
PubMed1979

Fine structure of the rabbit adrenal cortex and the effects of short-term ACTH administration.

The fine structure of the rabbit adrenal cortex was investigated. The parenchymal cells display the ultrastructural features of steroid-producing cells, and also contain numerous electron-dense bodies frequently located near intercellular canaliculi, when open into the subendothelial space. Short-term ACTH-administration induced a noticeable decrease in the volume of the lipid compartment in the cells of all three cortical zones and a significant increase in the volume of dense bodies in the cells of zona fasciculata and zona reticularis. The hypothesis that these dense bodies are secretory granules is discussed in the light of biochemical evidence showing that ACTH increases the concentration of both corticosterone and cortisol in the decapsulated-enucleated adrenal homogenate and does not affect the activity of two lysosome-marker enzymes (i.e., acid phosphatase and beta-glucuronidase).

Adrenal Cortex↗
PubMed1979

A stereological study of the trophic effects of the renin-angiotensin system on the rat adrenal zona glomerulosa.

Left renal artery stenosis increased and timolol maleate chronic administration decreased systolic blood pressure, plasma renin activity, and plasma aldosterone concentration, in adult male rats. In the hypertensive animals the volume of the zona glomerulosa, the volume and number of zona glomerulosa cells, as well as the volume of the mitochondrial compartment and the surface area of SER and mitochondrial cristae, were significantly increased. The volume of the lipid compartment was reduced, and several clumps of electron-dense granules appeared at the juxta-sinusoidal pole of the cells. Opposite results were found in the zona glomerulosa of the hypotensive rats, with the exception that the volume of the lipid compartment showed no significant change. These findings suggest that the renin-angiotensin system is involved in the maintenance and stimulation of the growth in the zona glomerulosa. Since in the hypertensive rats the increase in the volume density of electron-dense granules fits well with that in the intracellular concentration of aldosterone, the working hypothesis is that these granules are aldosterone-containing secretory organelles.

Adrenal Cortex↗
PubMed1979

Investigations into the mechanism of progesterone release by rat lutein cells.

Vinblastine treatment blocks progesterone release from the lutein cells of superovulated immature rat ovaries, without impairing hormone synthesis, and induces the accumulation of electron-dense granules, 0.2--0.3 micron in diameter, at the juxta-sinusoidal poles of the cells. The hypothesis is advanced that these granules are true secretory organelles and that an exocytotic mechanism underlies the progesterone release from rat lutein cells.

Animals↗
PubMed1977

Investigations on the turnover of adrenocortical mitochondria. VIII. A stereological study of the effect of chronic treatment with ACTH and dexamethasone on the morphology of mitochondria in zona glomerulosa cells of the rat.

The effects of chronic administration of ACTH and dexamethasone on the morphology of mitochondria in zona glomerulosa cells of the rat adrenal cortex were investigated by stereological techniques. It was found that the volume of the mitochondrial compartment as well as the surface of the outer and inner mitochondrial membranes were significantly increased or decreased in relation to the number of days of ACTH- or dexamethasone-treatment. In ACTH-administered rats, the average volume of individual mitochondria decreased significantly up to the 6th day of treatment and then showed a conspicuous increase from the 6th to the 15th day, whereas in dexamethasone administered animals this parameter, after a small increase during the first 6 days of treatment, displayed a significant decrease. The number of mitochondria per cell showed a dramatic increase during the first 6 days of treatment with ACTH and continued to increase, but only slightly, with the subsequent treatment. In contrast, this parameter showed a parabolic decrease as a function of the duration of treatment in animals receiving dexamethasone. In the light of evidence showing that dexamethasone blocks ACTH-release, these findings are discussed and interpreted to indicate that ACTH is involved in the maintenance and stimulation of the growth and proliferative activity of mitochondria in rat adrenal zona glomerulosa.

Adrenal Cortex↗
PubMed1977

Effects of ACTH and dexamethasone on the zona glomerulosa of the rat adrenal cortex: an ultrastructural stereologic study.

The effects of a chronic treatment with ACTH and dexamethasone on the zona glomerulosa of intact rat adrenals were investigated by morphometric methods and electron microscopy. It was found that ACTH increases the volume of the zona glomerulosa, of the cells, nuclei mitochondrial compartment as well as the surface of SER and mitochondrial compartment as well as the surface of SER and mitochondrial cristae. Also noticeable was the hypertrophy of the Golgi apparatus. Opposite effects were obtained after dexamethasone treatment. These findings are interpreted as indicating that ACTH is involved in the maintenance and stimulation of the growth and steroidogenic capacity of the adrenal zona glomerulosa.

Adrenal Cortex↗
PubMed1975

Investigations on the turnover of adrenocortical mitochondria. III. Stereologic and autoradiographic observations on the effect of chronic treatment with dexamethasone on the rat Zona fasciculata mitochondria.

The effects of chronic administration of dexamethasone (for up to 15 consecutive days) on both the morphology and DNA-synthesis of the mitochondria of the rat adrenal zona fasciculata were investigated by stereologic and autoradiographic techniques. Up to the 3rd day of continuous dexamethasone treatment, the average volume of mitochondria did not change, whereas the number of mitochondria per cell was significantly decreased. From the 3rd to the 15th day of hormonal administration both the volume and number of mitochondria were found to decrease in proportion to the duration of treatment. Autoradiography showed that after the 3rd day of dexamethasone administration there is virtually no incorporation of 3H-thymidine into the mitochondrial compartment. These findings are discussed in the light of evidence indicating that dexamethasone blocks ACTH-release by inhibiting the hypothalamo-hypophyseal axis. The results confirm the view that ACTH controls the maintenance of growth and proliferation of rat adrenocortical mitochondria.

Adrenal Cortex↗