Physiological response of American bullfrog tadpoles to stressor conditions of capture and hypoxia

Abstract

RESUMO.-[Resposta fisiológica de girinos de rã-touro americana submetidos aos mecanismos estressores de captura e hipóxia.] A rã-touro americana (Rana catesbeiana) recentemente denominada Lithobates catesbeianus é criada com propósito comercial em várias regiões do Brasil. Situações estressantes tais como problemas de manejo, criação inadequada e alterações ambientais com consequente redução da imunidade são comuns em produções intensivas. A avaliação destas situações de estresse permitenos detectar estes probemas e diminuir as injurias causadas pelo confinamento. O principal objetivo deste estudo foi utilizar os marcadores biológicos de cortisol, glicemia e dados hematológicos para avaliar a resposta de girinos de rã-touro submetidos aos mecanismos estressores de captura e hipóxia. Os animais foram distribuídosem três tratamentos: estresse por captura individual com puçá; estresse por captura em massa com puçá e estresse por captura por escoamento. Os resultados obtidos demostraram não haver diferenças estatisticamente significativas entre os parametros avaliados quando comparou-se os grupos com e sem exposição ao ar (normoxia e hipoxia). Com base nes- Stressful situations such as problems of management, inadequate facilities and environmental changes with consequent reduction of immunity are common in intensive production. The assessments of these situations of stress allow us detect these problems decreasing the injuries causes by confinement. The main objective of this study was to use the biological markers of plasma cortisol and glucose level and hematological parameters to evaluate the response of bullfrog tadpoles submitted to stressed mechanisms of capture and hypoxia. The animals were subjected to three treatments: stress due to individual capture with a hand net; stress due to batch capture with a hand net; and stress due to capture by emptying. The results obtained demonstrated that there were no statistically significant differences in the parameters tested when comparing the treatments with and without exposure to air (normoxia and hypoxia). Based on these results we can conclude that the stressful stimuli tested were not adequate to alter the biomarker tested. For the cortisol, probably this should have occurred due to the synergistic action between this hormone and thyroxin, which induces metamorphosis in these animals. tes resultados pode-se concluir que os estímulos estressores avaliados não foram adequados para alterar os valores plasmáticos dos marcadores biológicos testados. Para o cortisol, isto ocorreu provavelmente em virtude da ação sinérgica deste hormônio e a tiroxina, que induz a metamorfose nestes animais.

Profile of cortisol, glycaemia, and blood parameters of American Bullfrog tadpoles Lithobates catesbeianus exposed to density and hypoxia stressors

“…The red series haematological parameters for animals exposed to the stressor mechanisms are presented in Ta (Coppo et al2005) and values about Ht 22,5±5%; Hb 4,7±0,9g/100mL (Cathers et al 1997) . There were not significant differences between the treatments in the different collection days corroborating the reports from another study (Rocha et al 2010) on the same species of tadpoles.…”

“…However, these authors reported qualitative uncertainties regarding the analysed material, referring to it as "cortisol like". Studies with tadpoles of the same species and in the same developmental phase, found mean plasma cortisol values ranging from 2.14 to 5.0ng/mL after exposing the animals to the stressors capture and hypoxia (Rocha et al 2010). The Kruskal-Wallis test indicated that tadpole density had no effect on cortisol concentration.…”

“…In a study on bullfrog tadpoles, glycaemic values ranging from 20 to 64 mg/dL (Wang & Chang 1994), values ranging from 45 to 54mg/dL (Coppo et al 2005) and values ranging from 49.33 to 104.33mg/dL (Rocha et al 2010). In the present study, the values found were lower, ranging from 9.31 to 30.87mg/dL.…”

Comparative leukocyte morphometric analysis between endemic Anurans from Brazil and the invasive species Lithobates catesbeianus

“…Native to the eastern United States and Canada (GIOVANELLI et al, 2008;BOTH et al, 2011), L. catesbeianus was introduced in Brazil in the 1930s, in association with aquaculture (GIOVANELLI et al, 2008;ROCHA et al, 2010). L. catesbeianus was included in this study because of its economical importance and the variety of hematologic studies of this species available (CATHERS et al, 1997;COPPO et al, 2005;DAVIS, 2009;ROCHA et al, 2010).…”

“…L. catesbeianus was included in this study because of its economical importance and the variety of hematologic studies of this species available (CATHERS et al, 1997;COPPO et al, 2005;DAVIS, 2009;ROCHA et al, 2010).…”