Diet-induced obesity impairs AKT signalling in the retina and causes retinal degeneration

Retinopathy, a common complication of diabetes, is characterized by an unbalanced production of nitric oxide (NO), a process regulated by nitric oxide synthase (NOS). We hypothesized that retinopathy might stem from changes in the insulin receptor substrate (IRS)/PI3K/AKT pathway and/or expression of NOS isoforms. Thus, we analysed the morphology and apoptosis index in retinas of obese rats in whom insulin resistance had been induced by a high-fat diet (HFD). Immunoblotting analysis revealed that the retinal tissue of HFD rats had lower levels of AKT1, eNOS and nNOS protein than those of samples taken from control animals. Furthermore, immunohistochemical analyses indicated higher levels of iNOS and 4-hydroxynonenal and a larger number of apoptotic nuclei in HFD rats. Finally, both the inner and outer retinal layers of HFD rats were thinner than those in their control counterparts. When considered alongside previous results, these patterns suggest two major ways in which HFD might impact animals: direct activity of ingested fatty acids and/or via insulin-resistance-induced changes in intracellular pathways. We discuss these possibilities in further detail and advocate the use of this animal model for further understanding relationships between retinopathy, metabolic syndrome and type 2 diabetes. © 2012 John Wiley & Sons, Ltd.

Localization patterns of steroid and luteinizing hormone receptors in the corpus luteum of Nelore (Bos taurus indicus) cows throughout the estrous cycle

The aim of the present study was to detect progesterone receptors (A and B isoforms), α and β estrogen receptors, luteinizing hormone receptors and aromatase cytochrome P450 enzymes in the corpus luteum of Nelore (Bos taurus indicus) cows using immunohistochemistry. The estrous cycles of 16 Nelore cows were synchronized, and luteal samples were collected via an incision into the vaginal vault. Samples were collected during specific days of the estrous cycle (days 6, 10, 15 and 18) and 24. h after circulating progesterone dropped, after luteolysis had occurred. After each biopsy was taken, all animals were resynchronized so that each biopsy was performed during a different estrous cycle. Our results showed that the concentration of studied proteins vary throughout the bovine estrous cycle. The highest concentration of α and β estrogen receptors and the highest concentration of plasma progesterone were both observed on days 10 and 15 of the estrous cycle. The highest concentration of progesterone receptors was observed on days 6 and 10 of the estrous cycle, and the most intense immunostaining for cytochrome P450 aromatase enzymes was observed on day 10 of the estrous cycle. The highest score of cells with plasma membrane immunostaining for LH receptors was observed on day 15 of the estrous cycle. In conclusion, this study demonstrates the varying concentrations of specific proteins within the corpus luteum of Nelore cows during the estrous cycle. This finding suggests that these receptors and enzymes, and their interactions, are important in regulating luteal viability. © 2013 Elsevier B.V.

Heart failure-induced skeletal myopathy in spontaneously hypertensive rats

Background: Although skeletal muscle atrophy and changes in myosin heavy chain (MyHC) isoforms have often been observed during heart failure, their pathophysiological mechanisms are not completely defined. In this study we tested the hypothesis that skeletal muscle phenotype changes are related to myogenic regulatory factors and myostatin/follistatin expression in spontaneously hypertensive rats (SHR) with heart failure. Methods: After developing tachypnea, SHR were subjected to transthoracic echocardiogram. Pathological evidence of heart failure was assessed during euthanasia. Age-matched Wistar-Kyoto (WKY) rats were used as controls. Soleus muscle morphometry was analyzed in histological sections, and MyHC isoforms evaluated by electrophoresis. Protein levels were assessed by Western blotting. Statistical analysis: Student's t test and Pearson correlation. Results: All SHR presented right ventricular hypertrophy and seven had pleuropericardial effusion. Echocardiographic evaluation showed dilation in the left chambers and left ventricular hypertrophy with systolic and diastolic dysfunction in SHR. Soleus weight and fiber cross sectional areas were lower (WKY 3615±412; SHR 2035±224 μm2; P < 0.001), and collagen fractional volume was higher in SHR. The relative amount of type I MyHC isoform was increased in SHR. Myogenin, myostatin, and follistatin expression was lower and MRF4 levels higher in SHR. Myogenin and follistatin expression positively correlated with fiber cross sectional areas and MRF4 levels positively correlated with I MyHC isoform. Conclusion: Reduced myogenin and follistatin expression seems to participate in muscle atrophy while increased MRF4 protein levels can modulate myosin heavy chain isoform shift in skeletal muscle of spontaneously hypertensive rats with heart failure. © 2012 Elsevier B.V.

Biochemical, functional, structural and phylogenetic studies on Intercro, a new isoform phospholipase A2 from Crotalus durissus terrificus snake venom

Crotoxin is a neurotoxin from Crotalus durissus terrificus venom that shows immunomodulatory, anti-inflammatory, antimicrobial, antitumor and analgesic activities. Structurally, this toxin is a heterodimeric complex composed by a toxic basic PLA2 (Crotoxin B or CB) non-covalently linked to an atoxic non-enzymatic and acidic component (Crotapotin, Crotoxin A or CA). Several CA and CB isoforms have been isolated and characterized, showing that the crotoxin venom fraction is, in fact, a mixture of different molecules derived from the combination of distinct subunit isoforms. Intercro (IC) is a protein from the same snake venom which presents high similarity in primary structure to CB, indicating that it could be an another isoform of this toxin. In this work, we compare IC to the crotoxin complex (CA/CB) and/or CB in order to understand its functional aspects. The experiments with IC revealed that it is a new toxin with different biological activities from CB, keeping its catalytic activity but presenting low myotoxicity and absence of neurotoxic activity. The results also indicated that IC is structurally similar to CB isoforms, but probably it is not able to form a neurotoxic active complex with crotoxin A as observed for CB. Moreover, structural and phylogenetic data suggest that IC is a new toxin with possible toxic effects not related to the typical CB neurotoxin. © 2013.

Avaliação bioquímica, morfológica e funcional do músculo estriado esquelético de ratos na insuficiência cardíaca

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Caracterização molecular e expressão heteróloga do alérgeno fosfolipase A1 do veneno de Polybia paulista (Hymenoptera; Vespidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudos estruturais com a importina-α de mamíferos e peptídeos de sequências de localização nuclear (NLS)

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

Proteínas quinases de Neurospora crassa envolvidas na regulação do metabolismo de glicogênio: identificação das provavéis quinases que fosforilam a enzima glicogênio sintase

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Expressão dos fatores de regulação miogênica, composição das miosinas e trofismos no músculo esquelético periférico de ratos com insuficiência cardíaca crônica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Variação sexual, ontogenética e ambiental do veneno de Crotalus durissus terrificus da região de Botucatu - São Paulo: caracterização enzimática, bioquímica e farmacológica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Determinação da taxa de ovulação e sua relação com diâmetro folicular e isoformas de mRNA para receptor de LH, em vacas da raça Nelore

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo do músculo diafragma em ratos com insuficiência cardíaca crônica: composição das miosinas e expressão dos fatores de regulação miogênica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Caracterização morfológica, bioquímica e molecular do músculo esquelético sóleo de ratos espontaneamente hipertensos com insuficiência cardíaca

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo de isoenzimas de metabolismo de carboidratos e clonagem e expressão da enolase de Xylella fastidiosa

Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV

Burst oxidativo dos neutrófilos humanos: estudo da influência do polimorfismo do receptor para IgG FeyRIIIb na cooperação com os receptores para complemento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)