| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2004: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2003: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
The enteroinsular axis is known to enhance insulin secretion upon food ingestion. The insulin secretion has been postulated to consist of cephalic and intestinal phases. We have, however, reported that an instillation of glucose into the stomach which is ligated at the pylorus and fundus induces an insulin secretion related to glucose levels in the gastric vein, indicating a gastro-pancreatic link through the vagal nervous system in dogs. In the present study, to elucidate the link, we further examined whether the presence of glucose in the gastric vein or in the gastric lumen causes signals in the gastric vagal afferent system in rats anesthetized with urethane and chloralose. The afferent activity (the impulse discharge rate) in the filaments of the ventral or dorsal branch of the gastric vagus decreased in a dose-dependent fashion, when 1.0, 2.5 or 5.0% glucose (G) solution (200 microL) was injected into the subserosal space of the greater curvature. The decreases to each of the G s
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olutions were significant compared with changes to an injection of saline solution of corresponding osmolality. The afferents also decreased in response to the G solutions, but not to the saline solutions, instilled into the gastric lumen (500 microL). Furthermore, when 5.0% G solution was administered either into the subserosal space or into the gastric lumen, the efferent activity of the pancreatic vagus was facilitated significantly. However, both the subserosal and intraluminal G administrations applied to the totally vagotomized stomach did not facilitate the pancreatic efferents at all. These results indicate the existence of the vagal gastro-pancreatic reflex pathways, i.e., the reflex pathways between the gastric vagal afferent information triggered by presence of glucose in the stomach and the pancreatic vagal efferent information. This suggests that a unique insulin secretion induced by the vagal chemoreception of glucose in the stomach is involved in the enteroinsular axis, contributing to the regulation of postprandial nutrient homeostasis. Less
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