Ramón Piezzi

Effect of dehydroleucodine on mucus production : A quantitative study

We have demonstrated that dehydroleucodine(DhL), a lactone isolated from Artemisia douglasianaBesser, prevents gastroduodenal damage induced bynecrosis-inducing agents such as absolute ethanol. Wehave also reported, in a qualitative study, thatthis effect is related to the ability of the drug tostimulate mucus production. The present study wasdesigned to quantitatively evaluate the effect of DhL on adherent mucus layer thickness, to obtain amore objective approach to the mechanism of action ofthe drug. Mice were divided into two groups: (I)controls were treated with orally administeredcarboxymethylcellulose (CMC) and (II) experimental animals receivedDhL in CMC. The thickness of the mucus gel layer wasmeasured in unfixed stomachs and duodena, using an imageanalysis system. We observed an increase in the adherent mucus layer thickness in theexperimental samples. This confirms that one of the mainmechanisms involved in the cytoprotective action of thedrug is mucus secretion.

Vascularization of the hypophysial region of the normal and adenohypophysectomized toad

SummaryThe study of standarized sections of the hypophysial regions, and in vivo observations showed the presence of communicating vessels between the capillary network of the median eminence and the large capillaries of the neurointermediate junction. Moreover, direct branches from the hypophysial artery are described which give off branches, at the level of the neural stalk, to the median eminence and to the large capillaries of the neurointermediate junction.A second portal system similar to the one described by Cruz has been observed. Its primary plexus originates in several encephalic regions, and its secondary plexus is distributed through the neural lobe and thence to the pars intermedia. The course of flow in this system is a descending one. The arterial contribution to this system appears to arise from branches from the basilar and retroinfundibular arteries. — There are small venous-type vessels between the large capillaries of the neurointermediate junction and the posterodorsal region of the pars distalis. — After adenohypophysectomy, the blood which normally goes towards the pars distalis, flows towards the pars intermedia, following the path of the communicating vessels between the median eminence and the pars intermedia.

Novel anti-ulcer α,β-unsaturated lactones inhibit compound 48/80-induced mast cell degranulation

The present study was designed to examine the effects of a sesquiterpene lactone isolated from Artemisia douglasiana Besser (dehydroleucodine), a xanthanolide sesquiterpene isolated from Xanthium cavanillesii Schouw (xanthatin) and a semisynthetic butenolide (3-benzyloxymethyl-5H-furan-2-one) on mast cell degranulation induced by compound 48/80. Peritoneal mast cells from male adult Sprague-Dawley rats were purified in Percoll, preincubated in the presence of test lactones (dehydroleucodine, xanthatin or 3-benzyloxymethyl-5H-furan-2-one) and then challenged with the mast cell activator compound 48/80 (10 microg/ml). Concentration-response and kinetic studies of mast cell serotonin release evoked by compound 48/80, evaluation of mast cell viability and morphology by light and electron microscopy, and comparative studies using ketotifen and sodium chromoglycate were carried out. Serotonin release studies, carried out together with morphological studies, showed the effectiveness of the above lactones to stabilize mast cells. The comparative study with ketotifen and sodium chromoglycate, well known mast cell stabilizers, showed the following order of potency dehydroleucodine=xanthatin>3-benzyloxymethyl-5H-furan-2-one> or =ketotifen/sodium chromoglycate to inhibit mast cell serotonin release induced by compound 48/80. The present study provides the first strong evidence in favour of the hypothesis that dehydroleucodine, xanthatin and 3-benzyloxymethyl-5H-furan-2-one inhibit compound 48/80-induced serotonin release from peritoneal mast cells, acting thus as mast cell stabilizers. Our findings may provide an insight into the design of novel pharmacological agents which may be used to regulate the mast cell response.

The toad adrenal gland: I. Cortical cells during summer and winter☆

Abstract In this work we describe the seasonal changes occurring in the adreno-cortical cells of the toad Bufo arenarum Hensel. In summer, the gland presents wider cellular cords characterized by cells containing fewer lipid and cholesterol inclusions and maximal Δ 5 ,3 β -hydroxysteroid dehydrogenase activity. Under the electron microscope the summer gland shows a well developed smooth endoplasmic reticulum and numerous RNP particles, as well as dense mitochondria with occasional intramatrical granules. The winter gland, on the other hand, shows less developed smooth endoplasmic reticulum, larger and paler mitochondria, abundant lipid droplets, numerous lysosomes, particles of glycogen, and a poor Δ 5 ,3 β -hydroxysteroid dehydrogenase activity. The functional implications of these findings are discussed.

Gastroduodenal Mucosal Protection Induced by Dehydroleucodine: Mucus Secretion and Role of Monoamines

In previous work we have demonstrated thatdehydroleucodine (DhL) prevents gastric damage inducedby necrosis-inducing agents such as absolute ethanol(EtOH). In this study we examine the effects of DhL on gastroduodenal morphology and monoaminelevels by histological and biochemical methods,respectively, as an approach to elucidating thecytoprotective mechanism of the drug. Histologicalevidence shows that DhL prevents formation of gastroduodenalmucosal lesions induced by EtOH and that this protectiveeffect is related to the ability of the drug tostimulate mucus production. DhL itself does not affect the tissue concentration of NE, DA and 5-HT.However, it prevents the depletion of DA and 5-HTprovoked by EtOH. We propose that the abundant mucoidblanket secreted after treatment with DhL acts as adiffusion barrier against EtOH. It is also possible thatDhL could act as a “cell stabilizer,” byinhibiting the degranulation of cells containingmonoamines.

Ultrastructural and biochemical seasonal changes in epididymal corpus and cauda of viscacha (Lagostomus maximus maximus)

The reproductive and adaptative behavior of wild rodents is synchronized primarily by the photoperiod. The viscacha, a South American rodent of nocturnal habits and seasonal reproduction is photoperiod‐dependent and its reproductive behavior is regulated by the retinohypothalamic‐pituitary pineal axis. Adult males exhibit an annual reproductive cycle with periods of maximum gonadal activity (summer‐early autumn) and gonadal regression (winter). The corpus and the cauda, the most sensitive segments of the epididymis to changes induced by the photoperiod, were analyzed using electron microscopy and enzymatic biochemistry. During gonadal regression, principal and clear cells showed signs of involution with respect to the activity period. These were characterized by more irregular nuclei, smaller cytoplasms, large vacuoles, altered mitochondria, and glycogen deposits. All cellular populations of the epididymal epithelium in regression presented abundant lysosome‐like dense bodies during the active period. In addition, we measured the activity of four acid glycosidases in the cauda epididymis along the reproductive cycle. N‐acetyl‐β‐D‐glucosaminidase (NAG), an enzyme that degrades endocytosed substances from the epididymal lumen, increased significantly during gonadal regression relative to the active period. These results demonstrate that the viscacha epididymis exhibits significant ultrastructural and biochemical changes during the reproductive cycle. We demonstrate that during regression, melatonin secretion in viscacha increases. This study shows that the epididymal epithelium is reduced. Thus, we postulate that the changes observed in the epididymis are modulated by pineal melatonin. Despite these changes, the epididymis might maintain a microenvironment suitable for the survival of stored spermatozoa. J. Morphol. 2009.

Chromaffin tissue in the adrenal gland of the toad, Bufo arenarum Hensel

Abstract In the present work the topography of the toads adrenal is described. The gland consists of a branching system of cellular cords, sinusoid capillaries, and a venous system. The cords are made up of cortical cells and chromaffin cells. The latter can be classified in two morphological types. Type I cells are elongated, and have a smooth contoured nucleus and polymorphic chromaffin granules, a majority of which have a spherical shape. Type II cells are polygonal with an irregular nucleus and elongated chromaffin granules. Type I and Type II cells contain small mitochondria, lysosomes, and a juxtanuclear canalicular system (endoplasmic reticulum and Golgi complex). The probable role of the Golgi complex in the genesis of the chromaffin material as well as the significance of membrane-bounded granules in the walls of the capillaries are discussed.

The effects of adenohypophysectomy on the hypothalamic-hypophysial neurosecretory system and the adrenal gland of the toad Bufo arenarum Hensel

SummaryThe effects of adenohypophysectomy were studied on the hypothalamichypophysial neurosecretory system and the adrenal glands of Bufo arenarum Hensel. An increase in vascularization of the pars intermedia was found and the neurosecretory material (NSM) in the glandular region of the median eminence disappeared. Its reappearance later was accompanied by hypertrophy of the pars intermedia; differentiated chromophil cells appeared in the pars intermedia around the vessels and, at the same time, the adrenal reverted to normal. These findings are interpreted as hypertrophy and differentiation of the pars intermedia with replacement, at least partly, of the functions of the pars distalis. The probable mechanism of differentiation and the functions of chromophil cells of the pars intermedia are discussed.

Seasonal Morphological Variations and Age‐Related Changes of the Seminal Vesicle of Viscacha (Lagostomus maximus maximus): An Ultrastructural and Immunohistochemical Study

The viscacha is a seasonal rodent that exhibit an annual reproductive cycle with periods of maximum reproductive activity and gonadal regression. We studied seasonal variations in the morphology and cellular population of the seminal vesicles (SVs) during both periods and in impuber animals. Seminal vesicles were studied by light and electronic microscopy. Measurements of epithelial height, nuclear diameter, luminal diameter, and muscular layer were performed. Also, we studied the distribution of androgen receptors (AR) in this gland during the reproductive cycle and in impuber animal. During gonadal regression, principal and clear cells showed signs of reduced functional activity. These were characterized by an epithelium of smaller height, irregular nuclei, and cytoplasm with few organelles, dilated cisterns, and glycogen granules. In impuber animals, the principal cells showed large nuclei with chromatin lax and cytoplasm with small mitochondria, poorly developed Golgi apparatus, and granules of glycogen. On the other hand, the cells exhibited seasonal variations in the distribution and percentage of immunolabeled cells to AR throughout the annual reproductive cycle. During the gonadal regression period, glandular mucosa exhibited numerous epithelial cells with intense nuclear staining. However, fibromuscular stromal cells were weakly positive for AR in contrast to what was observed during the activity period. Considering that testosterone values are lower in adult animals during the period of gonadal regression and in impuber animals, our immunohistochemical results show a significant correlation with the percentage of AR‐immunopositive cells. In conclusion, these results demonstrate that the structure of the SVs changes in the activity period of viscacha, probably because of elevated levels of testosterone leading to an increase in the secretory activity of epithelial cells. Anat Rec,, 2012.

Serotonin content in the pineal gland of the antarctic penguin (Pygoscelis papua)

Abstract Pineal serotonin content of the penguin Pygoscelis papua , a migratory antarctic bird, was studied during January, 1972. Serotonin was assayed at 12 am and at 12 pm in animals with eyes exposed to light and in animals in which illumination had been prevented. In those with exposed eyes, the serotonin content was maximal at 12 pm ; those in which illumination was prevented showed similar values for 12 am and 12 pm .