Análise da atividade mitocondrial e mecanismos de adaptação em bovinos submetidos ao estresse pelo calor
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Data
2019-01-21
Autores
Ferreira, Gabriela da Silva
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Universidade Estadual Paulista (Unesp)
Resumo
Com aumento global da temperatura, compreender como o metabolismo de bovinos se adapta ao estresse térmico, permitirá selecionar animais melhor adaptados ao aumento da temperatura ambiente. Uma das possibilidades é compreender como cada raça responde a esse efeito ambiente. O trabalho objetivou expor ao sol duas raças distintas de bovinos com diferente resistência ao calor e estudar as alterações no metabolismo mitocondrial e comportamental após a exposição ao sol ou não por 60 dias. Foram analisados 23 animais da raça Angus – susceptível ao calor (12 ao sol e 11 sob sombra) e 25 Nelores – tolerantes ao calor (13 ao sol e 12 sob sombra). Após todos os animais passarem por período de adaptação de 60 dias, foram divididos entre os grupos e analisados os parâmetros ambientais (THI, HLI e AHLU), movimentação (por radiotelemetria), concentrações séricas de testosterona e LH por radioimunoensaio, espessura de tecido adiposo subcutâneo por ultrassonografia e atividade enzimática mitocondrial de músculo esquelético do complexo I (NADH oxidoredutase). A atividade mitocondrial foi avaliada em amostras da musculatura do tríceps braquial colhidas por biópsia periodicamente ao longo do experimento. Os parâmetros ambientais caracterizam o desconforto térmico que os animais foram submetidos, principalmente Angus sol com índice de AHLU muito acima de estresse extremo. Os Angus se movimentaram mais que os Nelore durante o período experimental (p<0,05) e os Nelore se movimentaram mais à noite em comparação ao dia (p<0,05). As concentrações de testosterona aumentaram do período de adaptação para o experimento para ambas as raças e tratamentos. Os animais da raça Nelore apresentaram maior depósito de gordura subcutânea que os Angus. A atividade mitocondrial aumentou significativamente do período de adaptação (P0) para o experimento (P1) e não diferiu durante o experimento entre as raça e os tratamentos. Animais endotérmicos mantidos em altas temperaturas respondem com adaptações metabólicas e comportamentais mediante o estresse exposto. Os Nelore se movimentam mais à noite quando a temperatura é mais amena e os Angus durante o dia à procura de conforto térmico. A atividade mitocondrial é aumentada devido a alta demanda de ATP provavelmente em repercussão da necessidade de sinalizar biogênese mitocondrial, reparação celular, movimentação e níveis aumentados de testosterona.
Cattle farmers are suffering challenges in the animal breeding, consequence of the global increase of the temperature. Understanding how the homeothermic metabolism adapts to the thermal stress, allows the selection of better adapted animals to the of the environmental temperature increase. One of those possibilities is to understand each breed reacts to this ambient effect. The work aimed to expose in the sun two different bovine breeds that have different heat resistance and evaluate the mitochondrial metabolism and behavioral changes during sun exposure. Twenty three Angus - susceptible to heat (12 in the sun and 11 in shadow) and 25 Nellore - heat tolerant (13 in the sun and 12 in shadow) animals were analyzed. After all the animals went through a 60 days adaptation period, the animals were sorted composing the groups and analyzed the environmental parameters, movement (by radiotelemetry) subcutaneous fat thickeness and mitochondrial enzymatic activity from squelectical muscle samples.The activity mitochondria were evaluated by the enzymatic reaction of the compound I (NADH oxidoreductase) in muscular tissue samples that were collected periodically during the experiment. The environmental parameters characterize the thermal discomfort that the animals were subjected to, mainly Angus sun with AHLU index well above extreme stress. The Angus moved more than the Nellore during the experimental period (p <0.05) and the Nellore moved more at night compared to the day (p <0.05). Testosterone concentrations increased from the adaptation period to the experimental for both breeds and treatments. The animals of the Nelore breed presented greater subcutaneous fat deposition than the Angus. Enzymatic mitochondrial activity increased significantly from the adaptation period (P0) to the experiment (P1) and did not differ during the experiment between breed and treatments. Homeothermic animals kept at high temperatures respond with metabolic and behavioral adaptations through exposed stress. The Nelore move more at night when the temperature is milder and the Angus during the day looking for thermal comfort. Mitochondrial activity is increased due to high ATP demand probably in repercussion of the need to signal mitochondrial biogenesis, cell repair, movement and increased levels of testosterone.
Cattle farmers are suffering challenges in the animal breeding, consequence of the global increase of the temperature. Understanding how the homeothermic metabolism adapts to the thermal stress, allows the selection of better adapted animals to the of the environmental temperature increase. One of those possibilities is to understand each breed reacts to this ambient effect. The work aimed to expose in the sun two different bovine breeds that have different heat resistance and evaluate the mitochondrial metabolism and behavioral changes during sun exposure. Twenty three Angus - susceptible to heat (12 in the sun and 11 in shadow) and 25 Nellore - heat tolerant (13 in the sun and 12 in shadow) animals were analyzed. After all the animals went through a 60 days adaptation period, the animals were sorted composing the groups and analyzed the environmental parameters, movement (by radiotelemetry) subcutaneous fat thickeness and mitochondrial enzymatic activity from squelectical muscle samples.The activity mitochondria were evaluated by the enzymatic reaction of the compound I (NADH oxidoreductase) in muscular tissue samples that were collected periodically during the experiment. The environmental parameters characterize the thermal discomfort that the animals were subjected to, mainly Angus sun with AHLU index well above extreme stress. The Angus moved more than the Nellore during the experimental period (p <0.05) and the Nellore moved more at night compared to the day (p <0.05). Testosterone concentrations increased from the adaptation period to the experimental for both breeds and treatments. The animals of the Nelore breed presented greater subcutaneous fat deposition than the Angus. Enzymatic mitochondrial activity increased significantly from the adaptation period (P0) to the experiment (P1) and did not differ during the experiment between breed and treatments. Homeothermic animals kept at high temperatures respond with metabolic and behavioral adaptations through exposed stress. The Nelore move more at night when the temperature is milder and the Angus during the day looking for thermal comfort. Mitochondrial activity is increased due to high ATP demand probably in repercussion of the need to signal mitochondrial biogenesis, cell repair, movement and increased levels of testosterone.
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Palavras-chave
Bovinos, Adaptação fisiológica, Metabolismo, Mitocôndrias, Temperatura corporal, Bovine, physiological adaptation, Metabolism, Mitochondria, body temperature