Isehunwa O. Grace and Alada AR Akinola
Keywords: Blood glucose, rainy season, dry season, adrenaline, cortisol, glucagon, Common African toad
Abstract: Hormones involved in the regulation of carbohydrate metabolism in amphibians have been shown to exhibit seasonal variable effects. The present study investigated the effects of adrenaline, glucagon, and cortisol on blood glucose level in the Common African toad Bufo regularis during three rainy and dry seasons. Adult toads of either sex weighing between 70-100g were randomly selected and used in the experimental study. Each animal was anesthetized with sodium pentobarbitone 3mg/100g body weight given intraperitoneally. The truncus arteriosus was used for blood sampling while the anterior abdominal vein was cannulated for injection of drugs. Blood sample was taken from truncus arteriosus to determine blood glucose using the modified glucose oxidase method. Adrenaline (10?g/kg) produced 70% increase in blood glucose during rainy season and 92% increase in blood glucose during dry season. Glucagon (10?g/kg) caused 102% increase in blood glucose during the rainy season and 88% increase in blood glucose during the dry season while cortisol (10?g/g) caused delayed but 50% increase in blood glucose during the rainy season and 61% increase in blood glucose during the dry season. The results of this study suggest that seasonal variation exists in the blood glucose response to adrenaline, glucagon and cortisol in the Bufo regularis. Therefore, seasonal changes should be taken into consideration in hormonal studies involving amphibians such as the B. regularis
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