Efeitos da variação metabólica sazonal sobre a hematologia e sistema bioquímico antioxidante de Salvator merianae (Squamata: Teiidae)
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Data
2018-02-28
Autores
Martins, Gabriela de Sousa
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Universidade Estadual Paulista (Unesp)
Resumo
Lagartos da espécie Salvator merianae possuem comportamento de hibernação sazonal, resultado de um ritmo fisiológico endógeno da espécie e caracterizado por redução drástica da taxa metabólica. Assim, há uma diminuição da atividade geral destes animais, os quais cessam sua movimentação e alimentação, além de reduzirem significativamente a frequência cardíaca e respiratória. Dessa forma, a oscilação entre a estação ativa e hibernação em S. merianae tem como consequência uma exposição constante a situações de depleção e retomada do consumo de oxigênio, bem como de flutuações na formação de espécies oxidantes (EO), o que faz com que seja imprescindível a atuação de um sistema antioxidante eficaz que possa prevenir os danos oxidativos ao organismo destes animais. Além disso, estes ajustes podem comprometer as células sanguíneas, uma vez que, em répteis, os valores hematológicos estão sujeitos a inúmeras alterações dependentes das condições fisiológicas e comportamentais às quais estão submetidos. Com isso, este estudo buscou avaliar as possíveis modificações na condição corporal geral, no metabolismo redox e perfil hematológico, decorrentes das mudanças fisiológicas e metabólicas únicas ocorridas no ciclo anual de S. merianae. Para isso foram utilizados seis espécimes de teiús, disponibilizados pelo Laboratório de Zoofisiologia Comparativa dos Vertebrados da UNESP de São José do Rio Preto – SP. Os animais foram previamente pesados, a temperatura corpórea foi aferida e coletou-se amostras de sangue da veia caudal em três períodos: pré-hibernação (fevereiro), hibernação (julho) e despertar (agosto). O metabolismo redox consistiu na análise das enzimas antioxidantes, CAT, GPx, GR, G6PDH e GST, e biomoléculas oxidadas, enquanto o perfil hematológico foi avaliado por meio de hemograma. Observou-se que durante o ciclo fisiológico de S. merianae os animais perdem relativamente pouca massa corpórea nos meses de hibernação, a qual é recuperada rapidamente no despertar. Além disso, a temperatura corporal oscila conforme o padrão comportamental dos animais nas diferentes estações do ano. Com relação ao metabolismo redox, o aumento na atividade de algumas enzimas antioxidantes durante a hibernação e despertar, somado aos altos níveis de biomoléculas oxidadas, sugere que houve estresse oxidativo na condição hipometabólica, mas demonstra que estes animais são capazes de suportar oscilações no equilíbrio redox. Por fim, a hibernação em S. merianae demanda ajustes na série vermelha de modo a tornar o transporte de gases eficiente, e o hipometabolismo característico do período parece suprimir o sistema imune, como evidenciado na série branca do tecido sanguíneo.
Tegu lizards, Salvator merianae, experience hibernation behavior as a result of an endogenous physiological rhythm, which is characterized by a drastic reduction in the metabolic rate. This condition leads to alterations on the behavior of these animals, with the decrease of their usual activities such as movements and feeding, in addition to significant reduction of heart and respiratory rates. Therefore, the oscillation between active and hypometabolic seasons in S. merianae results in constant exposure to depletion and resumption of oxygen, as well as fluctuations in the formation of oxidant species (OS), what makes essential the existence of an effective antioxidant system that should prevent oxidative damage in these animals. Moreover, these adjustments can affect the blood cells, because hematological values are susceptible to several changes in reptiles, depending on the physiological and behavioral conditions to which they are submitted. This work aimed to evaluate possible modifications in the general body condition, redox metabolism and hematological profile, resulted from the single physiological and metabolic changes in the annual cycle of S. merianae. The experiments were conducted with six specimens of tegus, available from the Comparative Vertebrate Zoophysiology Lab, from UNESP, São José do Rio Preto – SP. The animals were weighed, body temperature was measured and blood samples were collected from the caudal vein in three periods: active season (February), hibernation (July) and arousal (August). The redox metabolism evaluation consisted in the quantification of the antioxidant enzymes, CAT, GPx, GR, G6PDH and GST, and biomolecule oxidation levels, while the hematological profile was analyzed by hemogram. Thus, it was observed that, during the physiological cycle of S. merianae, the animals had a small lost of body mass during the months of hibernation, which was quickly recovered during arousal. In addition, the body temperature oscillates according to the behavior pattern of the animals during the different seasons of the year. In relation to redox metabolism, the increase in activity of some antioxidant enzymes during hibernation and arousal, combined with the high biomolecule oxidation levels, suggests that there was oxidative stress in the hypometabolic condition, but the lizards were able to tolerate oscillations in redox balance during their annual physiological cycle. Finally, hibernation in S. merianae requires adjustments in the red blood cells for efficient gas exchange, and the hypometabolism of the period appears to suppress the immune system.
Tegu lizards, Salvator merianae, experience hibernation behavior as a result of an endogenous physiological rhythm, which is characterized by a drastic reduction in the metabolic rate. This condition leads to alterations on the behavior of these animals, with the decrease of their usual activities such as movements and feeding, in addition to significant reduction of heart and respiratory rates. Therefore, the oscillation between active and hypometabolic seasons in S. merianae results in constant exposure to depletion and resumption of oxygen, as well as fluctuations in the formation of oxidant species (OS), what makes essential the existence of an effective antioxidant system that should prevent oxidative damage in these animals. Moreover, these adjustments can affect the blood cells, because hematological values are susceptible to several changes in reptiles, depending on the physiological and behavioral conditions to which they are submitted. This work aimed to evaluate possible modifications in the general body condition, redox metabolism and hematological profile, resulted from the single physiological and metabolic changes in the annual cycle of S. merianae. The experiments were conducted with six specimens of tegus, available from the Comparative Vertebrate Zoophysiology Lab, from UNESP, São José do Rio Preto – SP. The animals were weighed, body temperature was measured and blood samples were collected from the caudal vein in three periods: active season (February), hibernation (July) and arousal (August). The redox metabolism evaluation consisted in the quantification of the antioxidant enzymes, CAT, GPx, GR, G6PDH and GST, and biomolecule oxidation levels, while the hematological profile was analyzed by hemogram. Thus, it was observed that, during the physiological cycle of S. merianae, the animals had a small lost of body mass during the months of hibernation, which was quickly recovered during arousal. In addition, the body temperature oscillates according to the behavior pattern of the animals during the different seasons of the year. In relation to redox metabolism, the increase in activity of some antioxidant enzymes during hibernation and arousal, combined with the high biomolecule oxidation levels, suggests that there was oxidative stress in the hypometabolic condition, but the lizards were able to tolerate oscillations in redox balance during their annual physiological cycle. Finally, hibernation in S. merianae requires adjustments in the red blood cells for efficient gas exchange, and the hypometabolism of the period appears to suppress the immune system.
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Palavras-chave
Teiús, Hibernação, Estresse oxidativo, Células sanguíneas, Tegus, Hibernation, Oxidative stress, Blood cells