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Pancreas:
doi: 10.1097/MPA.0b013e3181f74b4b
Original Articles

Mechanism of Orexin B-Stimulated Insulin and Glucagon Release From the Pancreas of Normal and Diabetic Rats

Adeghate, Ernest MD, PhD; Hameed, Rasheed MSc

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Abstract

Objectives: To examine the pattern of distribution and effect of orexin B in the islets of normal and diabetic rats.

Methods: Pancreatic tissue fragments collected from normal and diabetic (4 weeks after the onset of diabetes) rats were either processed for immunohistochemistry or treated with different concentrations (10−12 to 10−6 mol/L) of orexin B.

Results: Orexin B-positive nerves were observed in the wall of blood vessels of both normal and diabetic rat pancreas. Orexin B is abundant in the islets of normal rats and colocalized with insulin in β cells. The number of orexin B-positive cells decreased after the onset of diabetes. Orexin B evoked significant (P < 0.05) increases in insulin release from the pancreas of normal and diabetic rats. Propranolol, a β-adrenergic receptor antagonist, significantly (P < 0.04) reduced the stimulatory effect of orexin B on insulin secretion. Orexin B also induced significant (P < 0.05) increases in glucagon release from the pancreas of normal rats but failed to stimulate glucagon secretion from the pancreas of diabetic rats.

Conclusions: Orexin B stimulated insulin secretion in normal and diabetic rat pancreas through the β-adrenergic pathway. Orexin B may have an important role in the regulation of islet function.

© 2011 Lippincott Williams & Wilkins, Inc.

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