C.L.A. Gómez Dumm

Tyrosine phosphorylation and morphological transfordmation induced by four vanadium compounds on MC3T3E1 cells

The present study was performed to determine the phosphotyrosine-protein levels induced by insulin and by four vanadium derivatives in MC3T3E1 osteoblast-like cells. We have also attempted to associate these patterns vath the vanadium-induced growth and morphological changes of such cells. Vanadate (Vi), vanadyl (VO), bis(maltolato)oxovanadium (IV) (BMOV) and bis(maltolato)dioxovanadium (V) (BMV) stimulate cell growth in a narrow range of concentration, but are also inhibitors for the cells at high concentrations. Vanadium-treated cells displayed clear changes in their morphology after overnight incubation. However, BMV was the least cytotoxic and the weakest inducer of morphological changes. All the compounds promote the phosphorylation of tyrosine residues in several proteins. This effect was more pronounced at low than at high doses. At low doses (10 μM), BMV showed a phosphorylation pattern similar to that of insulin, while Vi, VO and BMOV induced strong phosphorylation of cell proteins. The present findings suggest that the vanadium-induced growth regulation and morphological changes in MC3T3EI osteoblast-like cells are associated with the ability of these agents to increase the phosphotyrosine protein levels and to inhibite phosphotyrosine phosphatases. These properties are dependent on the oxidation state as well as on the organic ligand which coordinates the vanadium atom.

Effect of acute and exhaustive exercise upon the fine structure of heart mitochondria

Eine deutliche Vermehrung der Mitochondrienzahl und -grösse in den Herzrmiskelzellen wurde in Hunden durch erzwungenes Schwimmen (rasche und erschöpfende Leistung) festgestellt.

Ultrastructure of STH cells of the pars distalis of hepatectomized mice

SummaryAn electron microscopic analysis was performed on the pars distalis of the hypophysis of hepatectomized mice. Intact and sham operated mice served as controls. The STH cells presented striking changes that were most intense and widespread in those animals sacrificed at midnight of the second day after hepatectomy. These changes can be summarized as follows: 1) Hypertrophy of the Golgi complex with increased number of immature granules within the Golgi zone. This change appeared also in otherwise unmodified STH cells. 2) Strong dilatation of the endoplasmic reticulum whose cisternae contained much electron dense material. 3) Granules with partially diminished electron density, some of them in spatial relation with the plasma membrane and others swelling and bursting within the cytoplasm. All transitions between unchanged 350–400 mμ granules and extremely altered ones, were seen. 4) Release sites, characterized by dense zones in the plasmalemma, close to aggregates of electron lucent microvesicles, and almost empty granule membranes. 5) Increase in the density of the mitochondria which appeared grouped near the Golgi zone. 6) Increase in the number of large lysosomes of the autophagic vacuole type. 7) Irregular nuclear outlines. These data suggest increased synthesis and release of growth hormone in STH cells stimulated by hepatectomy.

Morphometric and ultrastructural analysis of different pituitary cell populations in undernourished monkeys

Undernutrition elicited by a low-protein diet determines a marked reduction of hypophyseal activity and affects the function of the respective target organs. The objective of the present investigation was to study the ultrastructural and quantitative immunohistochemical changes of the different pituitary cell populations in undernourished monkeys that had been previously shown to have significant changes in craniofacial growth. Twenty Saimiri sciureus boliviensis monkeys of both sexes were used. The animals were born in captivity and were separated into two groups at one year of age, i.e., control and undernourished animals. The monkeys were fed ad libitum a 20% (control group) and a 10% (experimental group) protein diet for two years. Pituitaries were processed for light and electron microscopy. The former was immunolabeled with anti-GH, -PRL, -LH, -FSH, -ACTH, and -TSH sera. Volume density and cell density were measured using an image analyzer. Quantitative immunohistochemistry revealed a decrease in these parameters with regard to somatotrophs, lactotrophs, gonadotrophs and thyrotrophs from undernourished animals compared to control ones. In these populations, the ultrastructural study showed changes suggesting compensatory hyperfunction. On the contrary, no significant changes were found in the morphometric parameters or the ultrastructure of the corticotroph population. We conclude that in undernourished monkeys the somatotroph, lactotroph, gonadotroph, and thyrotroph cell populations showed quantitative immunohistochemical changes that can be correlated with ultrastructural findings.

Ultrastructural and Quantitative Immunohistochemical Changes Induced by Nonsteroid Antiandrogens on Pituitary Gonadotroph Population of Prepubertal Male Rats

Specific blockade of the androgen receptor by the nonsteroid antiandrogens flutamide and Casodex has proven to be a useful tool for studying androgens in vivo. The aim of the present study was to investigate the effect of antiandrogen administration at the pituitary level by evaluating the ultrastructural changes in gonadotrophs, in correlation with the quantitative immunohistochemical findings, and by comparing these alterations with the effect of androgen deprivation by castration either with or without subsequent androgen replacement. Male Sprague-Dawley rats (23 days old) were grouped as follows: (1) controls, (2) flutamide-injected (10 mg/rat/day), (3) Casodex-injected (10 mg/rat/day), (4) castrated, and (5) castrated plus androgen-replaced (dihydrotestosterone propionate; 40 µg/rat/day). Groups were sacrificed after 10 days of maintenance under each condition. Pituitaries were processed for both light and electron microscopy. Serial sections (4 µm) were obtained at different levels and immunostained by means of the primary murine monoclonal antibodies anti-FSH and anti-LH and a peroxidase-mediated EnVision System (Dako). Volume density, cell density and mean cell area were measured with an image analysis system (Imaging Technology, Software Optimas 5.2). The mean cell area (p < 0.001) and the volume density (p < 0.05) increased significantly in the flutamide- and Casodex-treated groups as well as the castrated group of FSH and LH cells. On the other hand, androgen replacement in the castrated rats, however, reduced in both parameters related to control animals. The cell density of FSH-secreting cells was increased (p < 0.05) in the Casodex and flutamide treatment as well as castrated group. The cell density of LH-secreting cells was augmented (p < 0.05) in the Casodex-treated group, while there was no increase in such parameter with flutamide and castration. The ultrastructure of all groups showed two types of gonadotrophs. Type I cells contained large (300–500 nm) and small (150–200 nm) secretory granules, while type II cells were smaller, and exhibited only small granules (100–200 nm). Flutamide-treated, Casodex-treated and castrated groups presented a decreased number of secretory granules with some exocytotic profiles, well-developed rough endoplasmic reticulum and an expanded Golgi complex of both types of cells. The gonadotrophs from the castrated group exhibited numerous mitochondria with electron-dense ring-shaped laminar figures, while in the castrated plus androgen-replaced rats only a few mitochondria had similar changes to those observed in castrated animals, as a possible residual alteration. Finally, the gonadotrophs from flutamide-treated rats showed mitochondrial alterations with clear areas and isolated electron-dense laminar figures. In summary, we conclude that lack of androgen reaction through the effects of nonsteroid antiandrogens and castration on prepubertal rats produced a hypertrophia-hyperplasia of the FSH cells, and hypertrophia of LH-secreting cells, with marked alterations at the ultrastructural level suggestive of a hyperstimulation stage.

Sexual dimorphism in the age changes of the pituitary lactotrophs in rats.

It is known that aging is associated with alterations in hypothalamic and pituitary functions. In the present study, we have undertaken a quantitative immunohistochemical assessment of the lactotroph cell population as well as prolactin (PRL) secretion, in male and female rats of different ages. Pituitaries from young (3 months), old (20 months) and senescent (29 months) male and female Sprague-Dawley rats were processed for the immunohistochemical detection of lactotrophs. Serum PRL was measured by a homologous RIA. Additionally, the in vitro PRL secretory activity was estimated by perifusion of pituitary cells from senescent animals. Analysis of morphometric parameters revealed age-related changes of PRL cell population in animals of both sexes. The cell density (CD), surface density (SD) and volume density (VD) decreased with age in both male and female rats. However, CD as well as SD appeared to have increased in females when compared to males, either in young or old animals, while VD was higher only in old females. The pituitaries of senescent females displayed chromophobic microadenomas on a background of diffuse PRL cell hyperplasia. Prolactin serum levels showed a marked increase with age in females, but only a modest elevation in males. In senescent females, PRL production per cell was reduced. We conclude that in rats, there exists a clear sexual dimorphism in the age-related changes of pituitary PRL cells.

Growth hormone release after hepatectomy.

El plasma de ratones hepatectomizados, recogido a la medianoche del segundo día de la regeneración, estimula, al igual que la hormona de crecimiento pura, la síntesis de ADN de los hepatocitos y células litorales del hígado del ratón adulto intacto. Este efecto no se observa con el plasma de ratones intactos sacrificados a medianoche ni con solución fisiológica. Se sugiere que el factor estimulante del plasma de ratones hepatectomizados en hormona de crecimiento.

Immunohistochemical and Radioimmunological Assessment of Thyrotrophs in the Pituitary of Aging Rats

Thyrotrophs were studied by quantitative immunohistochemistry in the pituitary gland of young (4 months), old (20 months) and very old (29 months) male rats. An attempt was also made to correlate morphometric parameters with serum levels of thyrotropin (TSH), thyroxine (T4) and triiodothyronine (T3). Cells were immunostained by the peroxidase-antiperoxidase method and hormones were measured in serum by specific radioimmunoassays. There was a marked age-related reduction in TSH cell number, volume density and surface density but a significant increase in TSH cell area and perimeter. Basal serum levels of TSH increased, T4 decreased and T3 remained unchanged with age. There was a highly significant (p < 0.001) negative correlation between serum TSH and T4, but no significant correlation was found between TSH and morphometric parameters. The present results suggest that aged rats possess a reduced but functionally preserved thyrotrophic cell population. The coexistence of high circulating levels of TSH with reduced serum T4 suggests that aging brings about a progressive desensitization of the thyroid to TSH.

Quantitative immunocytochemical study of islet cell populations in diabetic calmodulin-transgenic mice

The present study describes the changes in the endocrine pancreas of severely diabetic calmodulin-transgenic mice using light microscopic immunocyto-chemical and morphometric techniques. A marked reduction in the number and volume of islets, together with distortion of their normal architecture, was found in diabetic mice. In addition, the volume density of both endocrine tissue and B-cells was decreased. An irregular distribution of non-B-cells was also observed in diabetic animals. The volume density and the percentage of A-cells appeared increased. However, when quantified per area unit, the number of all the islet cell types diminished, although only the decrease in B-cell number was statistically significant. The decrease in B-cell mass might account for the diabetic state developed in this animal model.

Effect of undernutrition on cranial components and somatotroph-lactotroph pituitary populations in the squirrel monkey (Saimiri sciureus boliviensis).

The aim of the present study was to investigate in monkeys the effects of undernutrition on neurocranial and facial components, correlated with a histometric and ultrastructural analysis of somatotroph (growth hormone, GH) and lactotroph (prolactin, PRL) pituitary populations. Twenty Saimiri sciureus boliviensis (Cebidae) of both sexes were employed. The monkeys were born in captivity and when they reached 1 year of age, they were separated into two groups: control and undernourished animals. They were fed ad libitum a 20% and 10% protein diet, respectively. The monkeys were radiographed when they were 3 years old in order to measure the length, width and height of the anterior, middle and posterior components of the neurocranium, as well as those of the masticatory, respiratory and optic components of the face. The volumetric and morphometric indices were then calculated. After the sacrifice, pituitary glands were processed for light and electron microscopy. The quantitative immunohistochemistry revealed a decrease in the volume density and cell density of both GH and PRL cells from malnourished animals when compared to control ones. The ultrastructural study showed changes suggestive of cellular hyperfunction for both types of cells in the former experimental group. Under nutrition also affected the size of the cranial components, with males being more affected than females; brain weight was, however, nonmodified by stress, with the brain/body ratio difference being the same for both sexes. We conclude that in monkeys, experimental undernutrition produces a decrease in the pituitary GH and PRL cell populations, in some way related to changes in the cranio-facial morphometric patterns.