| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Research Abstract |
We previously reported that intraportal appearance of glucagon-like peptide-1 (GLP-1) facilitates the hepatic vagal afferent activity (the impulse discharge rate) and further Reads to an increase of the pancreatic vagal efferent activity. The results indicated the presence of the vagal hepato-pancreatic reflex pathways, because the reflex was not observed in hepatic vagotomized rats, suggesting another nature of GLP-1 as neuroincretin in the enteroinsular axis. In the present study we further examined whether the vagal hepato-gastric reflex pathways, I.e., the reflex pathways between the hepatic vagi afferent information induced by GLP-1 and the gastric vagal efferent information. The same doses of GLP-1 as those in our previous study were employed for the intraportal injection in rats anesthetized with urethan and chloralose ; a 1-min bolus intraportal injection of 0.05, 0.2, or 4.0 pmol GLP-1 as aphysiologic, periphysiologic, or pharmacologic dose, respectively, was performed, because the 0.2 and 4.0 pmol injection, and 0.05 pmol weakly, facilitated the hepatic vagal afferents compared with vehicle injection. The intraportal injections attenuated tha gastric vagal efferents in normal, but not hepatic vagotomized, rats, suggesting a neurogenic enterogastrone effect. This pivotal role of the GLP-1-induced changes of the hepatic afferents was also observed upon intrafemoral injections at the GLP-1 doses. These results suggest a unique role of GLP-1 in regulation of postprandial nutrient homeostasis through the vagal chemoreception of GLP-1released into the portal vein.
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