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R S Piezzi

Publications and source records attributed to R S Piezzi.

At least 37 records · Page 2Linked to original sources
PubMed1983

Chromaffin reactions and fluorometric determination of catecholamines in the neonatal adrenal medulla of the rat.

Adrenaline and noradrenaline fluorometric determinations were simultaneously made in adrenal glands of 2-to-10 day-old rat with the histochemical localization of total catecholamines and noradrenaline. In 10-day-old-rats the increase is three times higher for adrenaline and four times higher for noradrenaline compared to 2nd day of age. Chromaffin cells of 2-to-10-day-old rats showed a low granular population preferentially located in the periphery of the cells. Seven days after birth the chromaffin granules were numerous and dispersed in extense areas of the cytoplasm. The dichromate reactions for total catecholamines were positive from the 5th day of age when the fluorometric determination was 250 ng of catecholamines (CA) per gland. The glutaraldehyde silver technique for noradrenaline was positive from the 7th day when the fluorometric determination was 35 ng of noradrenaline (NA) per gland. However, at the electron microscope level, this last reaction shows the same silver precipitates on the chromaffin granules in adrenal glands obtained from 4-to-6-day-old rats. These results indicate that the appearance and evolution of the chromaffin positive reaction during post natal development is a direct expression of molecular changes during maturation of the granular complex.

Adrenal Medulla↗
PubMed1983

Exposure to constant light increases pineal weight and RNA content in the pineal of the vizcacha (Lagostomus maximus maximus).

The following parameters, RNA and protein content, gland weight and nuclear size were studied in pineal glands of adult male vizcachas, maintained in captivity under permanent light (Lot I) and darkness (Lot II). The same determinations were performed in pineals of vizcachas shot at night in their normal habitat (Lot III, Control lot). A significant rise of gland weight and RNA content was observed in Lot I (with respect to the Control lot), while nuclear size and protein content were unchanged. The only significative differences between Lots I and II were also found in the pineal weight and RNA content. These results indicate that exposure of vizcachas to permanent light for 10 days does not produce inhibition of the parameters under study as occurs in other species. Apparently, the light acts as a stressor in these nocturnal mammals.

Animals↗
PubMed1981

Unusual cytoplasmic bodies in chromaffin cells of the adrenal medulla of the viscacha (Lagostomus maximus maximus).

Complex structures can be seen associated with large areas of endoplasmic reticulum of the chromaffin cells in the viscacha adrenal medulla. These structures are cylindrical in shape and are formed by chains of globular subunits. A central lumen is observed within which there are bodies resembling chromaffin granules. Parallel cisternae of the endoplasmic reticulum are arranged surrounding these bodies. The functional significance of these structures in unknown.

Adrenal Medulla↗
PubMed1981

Effect of dexamethasone on the neonatal adrenal medulla.

Newborn male rats were injected with a single dose of dexamethasone on the first day of life. Controls received only the diluent. Two to ten days later the experimental and control animals were sacrificed, and the adrenal medullae were processed for electron microscopy and for histochemical demonstration of catecholamines. Rats that received dexamethasone, as compared to controls showed (1) an earlier appearance of the catecholamine reactions, and (2) a pronounced development of Golgi complex. These results are further indication that glucocorticoid stimulates the maturation of the chromaffin complex. The Golgi apparatus may play some role in this inductive mechanism.

Adrenal Medulla↗
PubMed1980

Hydroxyindole-O-methyltransferase (HIOMT), catechol-O-methyltransferase (COMT) and histamine-N-methyltransferase (HNMT) in the pineal gland of the vizcacha (Lagostomus maximus maximus).

The activities of three methylating enzymes HIOMT, COMT, and HNMT were determined in pineal glands from 2 groups of adult vizcachas of both sexes, one (I) maintained under permanent lighting (15 days) and the other (II) kept in darkness. The control determinations (III) were carried out in pineal glands from animals hunted and killed during the night. In (I) the HIOMT activity decreased and the COMT activity increased; no changes were exhibited by HNMT. In (II) showed a diminished HIOMT activity. In captivity illumination affected HIOMT and COMT activites in a similar form to that observed in other species of rodents. The decrease in HIOMT activity in (II) suggests that captivity may affect pineal function, possibly as a consequence of a decrease in locomotor activity.

Acetylserotonin O-Methyltransferase↗
PubMed1977

Hydroxyindole-O-methyl transferase (HIOMT) and serotonin in the pineal gland of the vizcacha (Lagostomus maximus maximus).

Pineal glands of vizcachas collected from their natural habitat were studied. Hydroxyindole-O-methyl transferase (HIOMT) activity showed a great individual dispersion. However, the enzyme activity was significantly higher in males than in females. Serotonin was also assayed in the glands. It did not show significant differences between both sexes. The results are discussed in relation to the natural life conditions of this rodent.

Acetylserotonin O-Methyltransferase↗
PubMed1975

Electron microscopic studies on the pineal organ of the antarctic penguin, (Pygoscelis papua).

The pineal organ of the migratory antarctic penguin, Pygoscelis papua, has a lobular structure. Clusters formed by different types of parenchymal cells are separated by connective tissue septa containing blood vessels. The predominant cell type displays a well-developed Golgi complex, free ribosomes, clear and granular vesicles (secretory granules), and lysosomes. Other cell types found in the gland are supporting and ependymal-like cells. The former contain dense bodies and filament bundles, the latter possess abundant cilia and clusters of ribosomes. Typical photoreceptor elements are lacking. Blood vessels are located within a perivascular space bordered by basal laminae. This perivascular space extends between the basal protrusions of the parenchymal cells. The presence of pinocytotic vesicles, secretory granules and cytoplasmic processes in the vicinity of these spaces suggests active sites of transport and exchange of substances. Intercellular conaliculi-like spaces are surrounded by parenchymal cells rich in microvilli. These cancliculi are continuous with the cavities (invaginations) of secretory and other parenchymal cells.

Animals↗
PubMed1975

Comparative effect of insulin and explanted adrenal medullary tissue and rat adrenal medulla in situ.

The adrenal medulla and explanted medullary cells in the anterior chamber of the eye were examined 3 h after the administration of insulin to rats. No alterations were seen in the explanted cells. In the adrenal medulla, light and electron microscopy indicated depletion of adrenaline cells; noradrenaline cells were not affected. Levels of catecholamines were three times higher in the explanted tissue after insulin treatment; in the medulla in situ they declined by 70%. These results confirm that insulin has no direct releasing effect on chromaffin cells.

Adrenal Medulla↗
PubMed1970

Pituitary serotonin content: effects of melatonin or deprivation of water.

Relatively high concentrations of serotonin are found in the three regions of the rat pituitary gland. Administration of melatonin causes a selective increase in the serotonin concentration of the pars intermedia; deprivation of water for 5 days causes a selective decrease in the serotonin concentrations of the neural lobe and pars distalis.

Animals↗