Glucagon binding and lipolytic response in isolated adipocytes from streptozotocin-diabetic rats |
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Authors: | P Mayor C Calle |
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Institution: | Department of Biochemistry, School of Medicine, Complutense University, Madrid, Spain. |
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Abstract: | Evidence for pre-receptor, receptor and post-receptor glucagon defects was investigated in adipocytes from streptozotocin-diabetic rats. For this purpose male Wistar rats were injected by cardiac puncture with streptozotocin (65 mg/Kg body-weight) or saline solution and sacrificed after 7 and 15 days of drug administration. Increased glucagon levels and increased glucagon degradation in serum together with a decrease in glucagon binding were found in both groups of diabetic rats. The decrease in glucagon binding was related to a decrease in the number of glucagon receptors/cell rather than to a change in receptor affinity. The lipolytic response of glucagon was increased. However, the ability of glucagon to increase basal or theophylline-stimulated cAMP accumulation in the incubation medium of adipocytes from diabetic rats was decreased. Such alterations could represent a counter-regulatory mechanism of the hyperglucagonemia detected in streptozotocin-diabetic rats. |
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