MULLER CELLS AND DIABETIC-RETINOPATHY

Muller cells provide nutrition for neural cells. We studied the structure and ultrastructure of Muller cells in the retina of thirty 3-month old Wistar rats; divided equally into 3 groups: normal rats, alloxan diabetic rats and treated alloxan diabetic rats. 1 and 12 months after induction of diabetes. We observed that the Muller cell nuclei under light microscope examination had hexagonal shape and higher density than the other nuclei. Differences between groups could be observed only by electron microscopy. In the diabetic rats, Muller cells presented dispersion of nuclear chromatin and electrondense nuclear granulations, with the presence of increased glycogen, dense bodies and lysosomes in the cytoplasm. The alterations were more frequent in the perivascular region and at 12 months. The treated diabetic rats exhibited some alterations we observed in diabetic rats. but these alterations were less intense. We conclude that, despite the treatment, the diabetic retinopathy continues to evolve.

Hypothalamic melanin-concentrating hormone is induced by cold exposure and participates in the control of energy expenditure in rats

Short-term cold exposure of homeothermic animals leads to higher thermogenesis and food consumption accompanied by weight loss. An analysis of cDNA-macroarray was employed to identify candidate mRNA species that encode proteins involved in thermogenic adaptation to cold. A cDNA-macroarray analysis, confirmed by RT-PCR, immunoblot, and RIA, revealed that the hypothalamic expression of melanin-concentrating hormone (MCH) is enhanced by exposure of rats to cold environment. The blockade of hypothalamic MCH expression by antisense MCH oligonucleotide in cold-exposed rats promoted no changes in feeding behavior and body temperature. However, MCH blockade led to a significant drop in body weight, which was accompanied by decreased liver glycogen, increased relative body fat, increased absolute and relative interscapular brown adipose tissue mass, increased uncoupling protein 1 expression in brown adipose tissue, and increased consumption of lean body mass. Thus, increased hypothalamic MCH expression in rats exposed to cold may participate in the process that allows for efficient use of energy for heat production during thermogenic adaptation to cold.

EFFECT OF CAFFEINE ON THE METABOLISM OF RATS EXERCISING BY SWIMMING

Several studies have demonstrated that caffeine improves endurance exercise performance but the mechanisms are not fully understood. Possibilities include increased free fatty acid (FFA) oxidation with consequent sparing of muscle glycogen as well as enhancement of neuromuscular function during exercise. The present study was designed to investigate the effects of caffeine on liver and muscle glycogen of 3-month old, male Wistar rats (250-300 g) exercising by swimming. Caffeine (5 mg/kg) dissolved in saline (CAF) or 0.9% sodium chloride (SAL) was administered by oral intubation (1 mu l/g) to fed rats 60 min before exercise. The rats (N = and-IO per group) swam bearing a load corresponding to 5% body weight for 30 or 60 min. FFA levels were significantly elevated to 0.475 +/- 0.10 mEq/l in CAF compared to 0.369 +/- 0.06 mEq/l in SAL rats at the beginning of exercise. During exercise, a significant difference in FFA levels between CAF and SAL rats was observed at 30 min (0.325 +/- 0.06 vs 0.274 +/- 0.05 mEq/l) but not at 60 min (0.424 +/- 0.13 vs 0.385 +/- 0.10 mEq/l). Blood glucose showed an increase due to caffeine only at the end of exercise (CAF = 142.1 +/- 27.4 and SAL = 120.2 +/- 12.9 mg/100 ml). No significant difference in liver or muscle glycogen was observed in CAF as compared to SAL rats, at rest or during exercise. Caffeine increased blood lactate only at the beginning of exercise (CAF = 2.13 +/- 0.2 and SAL = 1.78 +/- 0.2 mmol/l). These data indicate that caffeine (5 mg/kg) has no glycogen-sparing effect on rats exercising by swimming even though the FFA levels of CAF rats were significantly higher at the beginning of exercise.

Calcifications in a clear cell mucoepidermoid carcinoma: a case report with histological and immunohistochemical findings

The aim of this study was to report an unusual case of mucoepidermoid carcinoma (MEC) in a 39-year-old woman. The tumor showed a prominent population of clear and intermediate basal cells. Clear cells rarely predominate over other cell types. Such cases are called clear cell variant of MEC. The case also revealed a variable amount of calcified material in the tumor mass. Calcifications are rare in clear cell MEC. These structures were periodic acid- Schiff positive and diastase resistant, excluding glycogen origin. Immunohistochemistry was performed, and the epidermoid component was positive for cytokeratin (CK) 7, CK13, CK14, and CK19. The mucous and clear cells presented mild staining for CK7. Cytokeratins 7, 13, and 19 stained luminal cells, and intermediate cells exhibited positivity for CK7, CK14, and vimentin. The origin of the calcifications is speculated to be the result of dystrophic calcification of the amorphous eosinophilic material secreted by intermediate basal cells.

EFFECTS OF INTRAUTERINE AND POSTNATAL PROTEIN-CALORIE MALNUTRITION ON METABOLIC ADAPTATIONS TO EXERCISE IN YOUNG-RATS

The effect of intrauterine and postnatal protein-calorie malnutrition on the biochemical ability to perform exercise was investigated in young male rats. Malnourished rats were obtained by feeding dams a low-protein (6%) casein-based diet prepared in the laboratory during pregnancy and lactation. Control rats received an isocaloric diet containing 25% protein. The low-protein diet contained additional starch and glucose. At 45 days of age, malnourished rats showed lower body weight, serum protein, albumin and glucose levels, hematocrit values and heart glycogen content but higher circulating free fatty acids and gastrocnemius muscle glycogen than control rats. In response to exercise (50 min of swimming), control rats displayed lower heart, gastrocnemius and liver glycogen levels whereas malnourished rats showed low glycogen levels only in the gastrocnemius muscle. Both control and malnourished rats showed high serum glucose and free fatty acid levels after exercise. In conclusion, protein-calorie malnutrition improved muscle glycogen storage but this substrate was broken down to a greater extent in response to exercise. Malnourished rats were able to perform exercise maintaining high blood glucose levels, as observed in control rats, perhaps as a consequence of the elevated availability of circulating free fatty acids.

Influência do banho de aspersão ante-mortem na eficiência da sangria e em parâmetros bioquímicos da carne bovina

To determine the effects of the pre-slaughter showering on some meat quality parameters, the biochemical changes in the Longus colli muscle and the bleeding efficiency were studied. Thirty-six Nelore steers were slaughtered in a commercial slaughterhouse. Eighteen animals were submitted to pre-slaughter showering; a control group of eighteen animals were slaughtered without showering. Samples were collected for evaluations in the muscle depth, in the anterior portion of longus colli muscle,just before chilling. Bleeding efficiency was evaluated through the ratio of muscle haemoglobin/blood haemoglobin using blood samples taken five seconds after bleeding, and muscle sample taken before chilling. Longus colli muscle samples were also used to determine glycogen, glucose, pH and acidity, 5, 24 and 48 hours after slaughtering. Multivariate methods were used to evaluate biochemical data and the bleeding efficiency data analysis followed the randomized block design. Haemoglobin retained in the muscle and bleeding efficiency were not affected (P > .05) by pre-slaughter showering. The pre-slaughter showering did not affect (P > .05) the glycolysis. There was a significant effect of time in glycogen, glucose, pH and acidity, in the first 24 hours.

Protein deficiency during pregnancy and lactation impairs glucose-induced insulin secretion but increases the sensitivity to insulin in weaned rats

We studied glucose homeostasis in rat pups from darns fed on a normal-protein (170 g/kg) (NP) diet or a diet containing 60 g protein/kg (LP) during fetal life and the suckling period. At birth, total serum protein, serum albumin and serum insulin levels were similar in both groups. However, body weight and serum glucose levels in LP rats were lower than those in NP rats. At the end of the suckling period (28 d of age), total serum protein, serum albumin and serum insulin were significantly lower and the liver glycogen and serum free fatty acid levels were significantly higher in LP rats compared with NP rats. Although the fasting serum glucose level was similar in both groups, the area under the blood glucose concentration curve after a glucose load was higher for NP rats (859 (SEM 58) mmol/l per 120 min for NP rats v. 607 (SEM 52) mmol/l per 120 min for LP rats; P < 0.005). The mean post-glucose increase in insulin was higher for NP rats (30 (SEM 4.7) nmol/l per 120 min for NP rats v. 17 (SEM 3.9) nnol/l per 120 min for LP rats; P < 0.05). The glucose disappearance rate for NP rats(0.7 (SEM 0.1) %/min) was lower than that for LP rats (1.6 (SEM 0.2) %/min; P < 0.001). Insulin secretion from isolated islets (1 h incubation) in response to 16.7 mmol glucose/l was augmented 14-fold in NP rats but only 2.6-fold in LP rats compared with the respective basal secretion (2.8 mmol/l; P <0.001). These results indicate that in vivo as well as in vitro insulin secretion in pups from dams maintained on a LP diet is reduced. This defect may be counteracted by an increase in the sensitivity of target tissues to insulin.

Effect of fasting on carbohydrate metabolism in frugivorous bats (Artibeus lituratus and Artibeus jamaicensis)

The compensatory changes of carbohydrate metabolism induced by fasting were investigated in frugivorous bats, Artibeus lituratus and Artibeus jamaicensis. For this purpose, plasma levels of glucose and lactate, liver and muscle glycogen content, rates of liver gluconeogenesis and the activity of related enzymes were determined in male bats. After a decrease during the first 48 h of fasting, plasma glucose levels remained constant until the end of the experimental period. Plasma lactate levels, extremely high in fed bats, decreased after 48 h of fasting. Similarly, liver glycogen content, markedly high in fed animals, was reduced to low levels after 24 h without food. Muscle glycogen was also reduced in fasted bats. The expected increase in liver gluconeogenesis during fasting was observed after 48 h of fasting. The activities of liver glucose-6-phosphatase and fructose-1,6-bisphosphatase were not affected by food withdrawn. on the other hand, fasting for 24 h induced an increase in the activity of liver cytosolic phosphoenolpyruvate carboxykinase. The data indicate that liver gluconeogenesis has an important role in the glucose homeostasis in frugivorous bats during prolonged periods of food deprivation. During short periods of fasting liver glycogenolysis seems to be the main responsible for the maintenance of glycemia. (C) 2005 Elsevier B.V. All rights reserved.

Energy Expenditure and Oxygen Consumption as Novel Biomarkers of Obesity-induced Cardiac Disease in Rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Acute exposure of a glyphosate-based herbicide affects the gills and liver of the Neotropical fish, Piaractus mesopotamicus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Storaged products and presence of acid phosphatase in fat body cells at pre-pupal worker stage of Apis mellifera Linnaeus, 1758 (Hymenoptera, Apidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Thyroid State and Tolerance of Mammalian Myocardium to Hypoxia

Thyroid hormone is known to affect myocardial glycogen stores and thereby possibly limit anaerobic performance of mammalian cardiac muscle. Thyroid hormone administration (3,5,T-triiodo-L-thyroxine, 300 mu g/kg/day, sc) for 10 days decreased left ventricle (LV) glycogen concentration relative to euthyroid animals (2.78 +/- 0.46 vs. 4.28 +/- 0.29 mg/g of LV (mean +/- SEM)) while increasing the percent of V(1) myosin isozyi-ne, contractile activity and cardiac mass. In contrast, thyroidectomy increased myocardial glycogen stores (8.50 +/- 0.56 mg/g of LV) and shifted the myosin isozyme toward V(3), prolonged contractile activity and decreased LV mass. Thyroxine administration for 3, 7 and 10 days to thyroidectomized animals progressively decreased contractile duration and increased LV mass. Thyroxine administration for 3 or 7 days to thyroidectomized rats did not reduce glycogen stores (7.75 +/- 1.02 and 9.62 +/- 1.16 mg/g of LV, respectively), whereas myocardial glycogen declined to 3.30 +/- 0.58 mg/g of LV after 10 days of treatment. During hypoxia, cardiac muscle from thyroidectomized rats maintained greater active force and developed less contracture relative to euthyroid and, to a greater extent, than hyperthyroid rats. Removal of glucose from the bath decreased anaerobic performance and impaired recovery; however, myocardium from thyroidectomized rats remained more tolerant to hypoxia than the euthyroid group. Overall, the intrinsic LV glycogen content was positively correlated to anaerobic performance. These data demonstrate that the thyroid state profoundly affects myocardial growth, contractility and anaerobic performance of rat myocardium. Although energy demand may affect function during hypoxia, anaerobic substrate reserve (cardiac glycogen concentration) appears to be the primary factor determining tolerance to hypoxic stress. J. Exp. Zool. 311A:399-407, 2009. (C) 2009 Wiley-Liss, Inc.

Functional and Structural Adaptations in the Pancreatic alpha-Cell and Changes in Glucagon Signaling During Protein Malnutrition

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Características histoquímicas e estruturais do testículo do morcego hematófago (Desmodus rotundus rotundus, Geoffrey, 1810).

The testicular stroma of the vampire bat including the testicular capsula and the lamina propria of the seminiferous tubuli, was strongly PAS-positive. This observation was a possible indication of great amounts of structural glycogen and other glycoconjugates at the level of smooth muscle cells; elongated contractile cells and/or collagen frameworks of the tunica albuginea and tubular lamina propria. In the last the basement membranes of the seminiferous tubules were particularly strongly PAS positive, as an indication of their neutral mucosubstances structural composition, previously described (Malmi et al., 1987). The epithelium lining from the cavitary and surface rete testis complex showed low reactivities to mucosubstances; total proteins and lipids and oxidative enzymes studied. Although the apical granulation at the rete testis epithelium showed an intense PAS reactivity with hypothesis of glycoprotein secretion, through the rete. The PAS, Sudan Black B, NADH, MDH and LDH reactions of the testicular interstitium seem correlate to steroid metabolism (biosynthesis and secretion), at the Leydig cells level. The seminiferous epithelium generally had low reactions to all the histochemical studies realized. Particularly in the adbasal compartment the histochemical localizations of NADH diaphorase and LDH were possible related to glycolytic activities and general carbohydrates metabolism, both enzymes, and hydrogen transport, the NADH. The strong PAS, diastase and PAS, and alcian blue pH 2.5 and PAS reactions observed in the adluminal seminiferous epithelium compartment were directly related to the spermatids acrosomal glycoconjugates structuration. Also the SDH localization at this level seems to be related to the mitochondrial activities at the middle piece level in the late spermatids.