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Biomedical subjects

G Mazzocchi

Publications and source records attributed to G Mazzocchi.

At least 181 records · Page 10Linked to original sources
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

Growth hormone secretion in pubertal and adult subjects.

GH responsiveness to insulin-induced hypoglycaemia and its circadian secretion were studied in a group of subjects in different pubertal stages. The GH peak after insulin was minimal in stage 1 boys (7.6 +/- 1.3 (SEM) ng/ml) and increased progressively, in parallel with pubertal maturation, reaching a maximum in the adult state (20 +/- 4.0 ng/ml); the basal value was superimposable in all groups studied. The circadian secretion showed a sleep-related surge which was almost identical in the different stages; however in pubertal stage 1 boys multiple secretory peaks were observed, mainly during waking hours. A statistically significant difference (P less than 0.05) was observed in the mean concentration recorded during the day with a maximum in stage 1 boys (2.7 +/- 0.2 ng/ml) and a gradual decrease to a minimum in adults (1.2 +/- 0.3 ng/ml). This pattern seems to suggest that pulsatile rhythm is present in boys, similar to that observed for gonadotrophins.

Adolescent↗
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

Growth hormone, prolactin and cortisol nyctohemeral variations during naloxone-induced opiate receptor blockade in man.

To evaluate the role of endogenous opioid peptides in prolactin (Prl), growth hormone (GH) and cortisol neuroregulation, 50 mg of the opiate antagonist naloxone was infused over 24 h to 6 normal male volunteers. An additional naloxone dose (5 mg) was given iv as a bolus injection at 20.00 h. blood specimens were collected hourly by means of a portable constant withdrawal pump. Naloxone failed to alter 24 h secretion of GH and Prl. The sleep-related GH and Prl rise was also unaffected by the opiate blocker. Moreover, naloxone failed to alter the circadian rhythm of cortisol and its 24 h concentration. The results do not suggest, a major role of opiate receptors in spontaneous GH, Prl and cortisol secretion in man.

Adult↗
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

Stereological and biochemical investigations on a possible aldosterone-containing secretory organelle in the zona glomerulosa of rat adrenal gland.

Chronic angiotensin treatment induced a significant increase in the number of dense bodies in rat zona glomerulosa cells. The possible lysosomal nature of these organelles can be excluded, since in the zona glomerulosa of the treated animals the intracellular activity of some lysosome-marker enzymes (acid-phosphatase, beta-glucuronidase, and N-acetyl-beta-glucosaminidase) did not display significant changes. Stereological and radioimmunological analysis demonstrated that the angiotensin-induced increase in the volume density of dense bodies was associated with a comparable increase in the intracellular concentration of aldosterone. The hypothesis of the secretory nature of these granules is discussed.

Adrenal Glands↗
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↗
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↗
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

Ultrastructure of cortisol-secreting adrenal adenomata.

Two adrenocortical adenomata causing Cushing's syndrome were examined by electron microscopy. Adenomatous cells were arranged in islets and contained ovoid nuclei with a prominent nucleoli. Mitochondria were polymorphic and displayed tubular and lamelliform cristae. Some cells were apparently devoid of lipid droplets and possessed an exceedingly well developed SER, the tubules of which were intermingled with small stacks of ribosome-studded cisternae, while other parenchymal cells contained large clumps of lipid droplets and scanty SER tubules. A conspicuous Golgi apparatus and many dense bodies of probable lysosomal nature were also observed. These findings suggest that the adenomata are derived from the zona fasciculata and that lipid-laden and lipid-free cells are, respectively, resting and actively secreting elements.

Adenoma↗
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↗