A estrutura do fígado de micos-leões de cativeiro (Callithrichidae, Primates): uma abordagem estereológica

Estudos sobre a morfologia e estereologia hepática são relevantes em pesquisa de anatomia e patologia comparada. Estes também facilitam o uso de primatas não-humanos como modelos experimentais em pesquisa básica, fato que tem auxiliado os estudos em medicina humana. Estudos quantitativos de estruturas hepáticas também têm sido mais prevalentes em Primatas do Velho Mundo e outros vertebrados. Foram estudados vinte e três fígados de micos-leões adultos, sendo : 06 Leontopithecus rosalia, 07 Leontopithecus chrysomelas e 10 Leontopithecus chrysopygus, os quais foram dissecados e fixados com formol tamponado a 10%. Para a quantificação estereológica, o fígado foi considerado como consistindo de parênquima (hepatócitos) e estroma (não-hepatócitos). O parâmetro estereológico densidade de volume (Vv) foi determinado por contagem de pontos, utilizando-se do sistema teste M42. As diferenças estereológicas hepáticas entre as três espécies de micos-leões não foram estatisticamente significativas. Portanto, um valor único de V V [hepatócito] e Vv [estroma] podem ser determinados como 96, 2% e 7,4%, respectivamente. Significantemente diferente, os valores encontrados para o V V [hepatócito] em micos-leões foram 0,09 vez maior do que em babuínos, e 0,17 em humanos. Contudo, o Vv [estroma] foi 1,04 vez menor do que o de babuínos e 1,79 vez menor do que o de humanos. As diferenças encontradas entre as proporções estudadas, mesmo que não comprovadas estatisticamente, mostram a necessidade de estudos futuros para correlacionar os aspectos morfo-fisiológicos destes micos.Studies on liver morphology and stereology are relevant to the comparative anatomical and pathological research. They also facilitate the use of nonhuman primates in basic research, which has substantially supported studies in human medicine. Quantitative studies of liver structures have also been more extensive in Old World primates and other vertebrates. Twenty-three livers of adult lion tamarins were studied (06 Leontopithecus rosalia, 07 Leontopithecus chrysomelas, and 10 Leontopithecus chrysopygus), dissected, and fixed in 10% neutral buffered formalin solution. For stereological quantification, the liver was regarded as consisting of parenchyma (hepatocytes) and stroma (nonhepatocytes). The stereologic parameter volume density (Vv) was determined by point counting, using M42 test-system. Hepatic stereological differences among the three species of lion tamarins were not statistically significant. Therefore, the pooled V V [hepatocyte] and Vv [stroma] could be determined as 96.2% and 7.4%, respectively. Significantly different, the values found for V V [hepatocyte] in lion tamarins were 0.09 times greater than those in baboons, and 0.17 in man. However, the Vv [stroma] was 1.04 times smaller than that in baboons and 1.79 times smaller than that in man. The differences found among the rates studied, even if not proven statistically, point out to the need for further studies to correlate the morphological and physiological features of those tamarins

Modulation of cytokines, resistin, and distribution of adipose tissue in C57BL/6 mice by different high-fat diets

AbstractObjectiveTo investigate whether changing the lipid source induces metabolic changes and/or modulates the adipose tissue distribution in mice fed with a high-fat (HF) diet.MethodsC57BL/6 mice were subjected to a 10-wk control diet (10% fat) or an HF diet (60% fat) containing lard (HF-L), olive oil (HF-O), sunflower oil, or canola oil. Food intake and body weight were measured. At euthanasia, blood was collected and adipose tissue was dissected. Serum hormones and cytokines were determined.ResultsThe plasma insulin levels were higher in the HF-L and HF-O groups than in the other three groups (P < 0.0001). The levels of resistin were highest in the HF-L and HF-O groups (P < 0.0001). Leptin expression was also highest in these two groups (P < 0.0001). Of the four groups, interleukin-6 was expressed at the highest level in the HF-L group (P < 0.0005), whereas adiponectin was expressed at the lowest level (P < 0.0001). The accumulation of subcutaneous and visceral adipose tissues was higher in the HF-L group compared with the other groups. This group was hypertrophic because of excess subcutaneous fat and epididymal fat in the adipocytes. However, the ratio of subcutaneous to visceral fat was significantly lower in the HF-L and HF-O groups compared with the other groups.ConclusionIn mice fed fat-rich diets, the level of adipokines, the distribution of adipose tissue, and the metabolism of carbohydrates are more significantly influenced by the lipid content rather than the absolute amount of lipid

Enalapril alters the formation of the collagen matrix in spontaneously hypertensive rats

OBJECTIVE: To assess the effect of the inhibition of the angiotensin-converting enzyme on the collagen matrix (CM) of the heart of newborn spontaneously hypertensive rats (SHR) during embryonic development. METHODS: The study comprised the 2 following groups of SHR (n=5 each): treated group - rats conceived from SHR females treated with enalapril maleate (15 mg. kg-1.day-1) during gestation; and nontreated group - offspring of nontreated females. The newborns were euthanized within the first 24 hours after birth and their hearts were removed and processed for histological study. Three fields per animal were considered for computer-assisted digital analysis and determination of the volume densities (Vv) of the nuclei and CM. The images were segmented with the aid of Image Pro Plus® 4.5.029 software (Media Cybernetics). RESULTS: No difference was observed between the treated and nontreated groups in regard to body mass, cardiac mass, and the relation between cardiac and body mass. A significant reduction in the Vv[matrix] and a concomitant increase in the Vv[nuclei] were observed in the treated group as compared with those in the nontreated group. CONCLUSION: The treatment with enalapril of hypertensive rats during pregnancy alters the collagen content and structure of the myocardium of newborns

Quantitative study of myocardial microcirculation in arterial hypertension due to progressive inhibition of NO synthesis

OBJECTIVE: To study the quantitative changes in intramyocardial blood vessels in rats in whom nitric oxide synthesis was inhibited. METHODS: Four groups of 10 rats were studied: control (C25 and C40) and L-NAME (L25 and L40). The animals L25 and L40 received L-NAME in the dosage of 50mg/kg/day for 25 and 40 days, respectively. On days 26 and 41 the animals in groups 25 and 40 were sacrificed. Analysis of the myocardium was performed using light microscopy and stereology. RESULTS: Arterial blood pressure and heart weight increased 74.5 and 57.8% after 25 days and 90.2 and 34.6% after 40 days, respectively. Comparing the L-NAME rats with the respective controls revealed that vessel volume density decreased 31.3% after 40 days, and the vessel length-density decreased 53.5% after 25 days and 25.7% after 40 days. The mean cross-sectional area of the vessels showed an important reduction of 154.6% after 25 days. The intramyocardial vessels decreased significantly in length- density in the L-NAME animals. The mean cross-sectional area of the vessels, which normally increases during heart growth between 25 and 40 days, showed a precocious increase by the 25th day in the L-NAME rats. This suggests an increase of the size of the heart, including blood vessels. CONCLUSION: The inhibition of the NO synthesis provokes rarefaction in the intramyocardial vessels that progresses with the time of administration of L-NAME

Myocardial repair with long-term and low-dose administration of a nitric oxide synthesis inhibitor. Myofibroblasts, type III collagen and fibronectin

OBJECTIVE: To study the healing process of the myocardium in hypertensive rats undergoing inhibition of nitric oxide synthesis. METHODS: Two groups of animals were studied: one received L-NAME, 12mg/kg/day, and the other was a control group. The presence of type III collagen, fibronectin, and alpha-smooth muscle actin-positive cells was assessed by immunohistochemistry. RESULTS: Fibronectin was seen in both early and late lesions, while type III collagen was seen mainly in areas of incomplete healing, situated among myocytes and around the intramyocardial branches of the coronary arteries. Areas representing early and late lesions showed a population of spindle-shaped cells. Immunohistochemistry showed that these cells were positive for alpha-smooth muscle actin. CONCLUSION: In the myocardium of hypertensive rats, the alpha-smooth muscle actin-positive cells are related to the accumulation of type III collagen and fibronectin in the areas of myocardial damage