Navegando por Palavras-chave "Thyroxin"

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    Efeitos da ingestão de presas sobre o metabolismo energético e os níveis hormonais de cascavéis Crotalus durissus (Serpentes, Viperidae)
    (Universidade Federal de São Paulo, 2014-04-28) Oliveira, Fernando Bagnariolli de [UNIFESP]; Carvalho, José Eduardo de [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Snakes that have foraging strategy such as ?sit-and-wait? and consequently feed on infrequent mode are excellent models to study the transition between the period of fasting and postprandial. The period of ingestion is accompanied by profound changes metabolism, thus an investigation of hormones related to metabolism and an analysis of the capacity of enzymatic pathways could elucidate questions about the processes that regulate this transition from fasting to feed. In this sense we analyze the concentration of thyroid hormones present in the plasma of rattlesnakes Crotalus durissus addition and leptin in plasma in fasted conditions and after ingestion of prey. In the same period we also analyzed the metabolic capabilities through measures of maximum activity of enzymes of glycogen synthesis (glycogen synthase - GS), an enzyme of the gluconeogenesis pathway (fructose 1,6 bisphosphatase - FBPase), enzymes of ? -oxidation lipid (? - hydroxyacyl -CoA dehydrogenase - HOAD), enzyme and metabolic pathway of ketone bodies (succinyl - CoA cetotransferase - SKT b - hydroxybutyrate dehydrogenase - HBDH) in tissue samples from liver, muscle, heart, kidney, stomach and intestine for fasted animals (45 and 90 days fasted) and after ingestion of the equivalent of 10 % of their body weight in mass of prey (24 hours, 48 hours and 120 hours). No different concentrations were found for the groups in the three hormones examined, T3, T4 e leptin. In the liver of rattlesnakes occurs regulation to form glycogen, analyzed by GS activity, in animals fed 48 hours after ingestion. Similar as result found in the kidney and muscle. With the exception of the heart, in all tissues there was a decrease in the ability to produce glucose from the gluconeogenesis, analyzed by FBPase in fasted animals for 90 days. In the heart there were also increased pathways of oxidation of lipids in fasted animals for 45 days, analyzed by HOAD, and increased metabolic pathway of ketone bodies in animals in 90 days fasting. These results suggest that although the hormones do not exert a regulatory role at least under the experimental conditions, the pathways analyzed by enzyme activities indicate possible points of regulations for times of fasting animals that foraging by ?sit-and-wait? strategies may face.