The effect of calcitonin gene-related peptide (CGRP) on glucose metabolism was investigated in conscious and unrestrained rats in vivo. Intravenous injection of rat CGRP (5.67 and 0.567 nmol/kg) caused a significant, dose-dependent increase in plasma glucose concentration and a simultaneous dose-dependent increase in plasma insulin level. In contrast, plasma glucagon level was not changed. On the other hand, intravenous infusion of CGRP (46.6 pmol · kg−1 · min−1) decreased tolerance to intragastric administration of glucose (IGGTT). Plasma insulin response to IGGTT, however, was not affected by CGRP infusion. Moreover, although intravenous injection of CGRP (5.67 nmol/kg) elicited a significant increase in plasma epinephrine and norepinephrine concentrations, concomitant administration of epinephrine and norepinephrine, inducing a more prominent rise in plasma catecholamines than those induced by CGRP, affected neither plasma glucose nor insulin levels. Finally, plasma insulin levels obtained by simulating CGRP-induced changes in plasma glucose or glucose plus catecholamine levels by infusion of glucose or glucose plus catecholamines were not different from those induced by CGRP injection. These results suggest that CGRP has a hyperglycemic action that is not mediated by sympathetic outflow in conscious rats, and inhibition of insulin secretion, if any, does not play a major role in this hyperglycemic action of CGRP. We have demonstrated specific CGRP receptors linked to adenylate cyclase activation in rat liver plasma membranes; this hyperglycemic effect of CGRP in vivo may be partly due to its direct action on the liver.
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Original Articles|
February 01 1990
Calcitonin Gene—Related Peptide and Induction of Hyperglycemia in Conscious Rats In Vivo
Akinori Yamaguchi;
Akinori Yamaguchi
Third Division, Department of Medicine, and the International Center for Medical Research, Kobe University School of Medicine
Kobe
Department of Medicine, Hyogo Prefectural Awaji Hospital
Sumoto, Japan
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Tsutomu Chiba;
Tsutomu Chiba
Third Division, Department of Medicine, and the International Center for Medical Research, Kobe University School of Medicine
Kobe
Department of Medicine, Hyogo Prefectural Awaji Hospital
Sumoto, Japan
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Tomoyuki Morishita;
Tomoyuki Morishita
Third Division, Department of Medicine, and the International Center for Medical Research, Kobe University School of Medicine
Kobe
Department of Medicine, Hyogo Prefectural Awaji Hospital
Sumoto, Japan
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Akira Nakamura;
Akira Nakamura
Third Division, Department of Medicine, and the International Center for Medical Research, Kobe University School of Medicine
Kobe
Department of Medicine, Hyogo Prefectural Awaji Hospital
Sumoto, Japan
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Tetsuya Inui;
Tetsuya Inui
Third Division, Department of Medicine, and the International Center for Medical Research, Kobe University School of Medicine
Kobe
Department of Medicine, Hyogo Prefectural Awaji Hospital
Sumoto, Japan
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Toshiyuki Yamatani;
Toshiyuki Yamatani
Third Division, Department of Medicine, and the International Center for Medical Research, Kobe University School of Medicine
Kobe
Department of Medicine, Hyogo Prefectural Awaji Hospital
Sumoto, Japan
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Seizo Kadowaki;
Seizo Kadowaki
Third Division, Department of Medicine, and the International Center for Medical Research, Kobe University School of Medicine
Kobe
Department of Medicine, Hyogo Prefectural Awaji Hospital
Sumoto, Japan
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Kazuo Chihara;
Kazuo Chihara
Third Division, Department of Medicine, and the International Center for Medical Research, Kobe University School of Medicine
Kobe
Department of Medicine, Hyogo Prefectural Awaji Hospital
Sumoto, Japan
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Masaaki Fukase;
Masaaki Fukase
Third Division, Department of Medicine, and the International Center for Medical Research, Kobe University School of Medicine
Kobe
Department of Medicine, Hyogo Prefectural Awaji Hospital
Sumoto, Japan
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Takuo Fujita
Takuo Fujita
Third Division, Department of Medicine, and the International Center for Medical Research, Kobe University School of Medicine
Kobe
Department of Medicine, Hyogo Prefectural Awaji Hospital
Sumoto, Japan
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Address correspondence and reprint requests to Dr. Akinori Yamaguchi, Third Division, Department of Medicine, Kobe University School of Medicine, Kusunoki-cho, Chuo-ku, Kobe 650, Japan.
Diabetes 1990;39(2):168–174
Article history
Received:
November 03 1988
Revision Received:
August 13 1989
Accepted:
August 13 1989
PubMed:
2227123
Citation
Akinori Yamaguchi, Tsutomu Chiba, Tomoyuki Morishita, Akira Nakamura, Tetsuya Inui, Toshiyuki Yamatani, Seizo Kadowaki, Kazuo Chihara, Masaaki Fukase, Takuo Fujita; Calcitonin Gene—Related Peptide and Induction of Hyperglycemia in Conscious Rats In Vivo. Diabetes 1 February 1990; 39 (2): 168–174. https://doi.org/10.2337/diab.39.2.168
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