Glucose signal in the nucleus of the vagus nerve modulates the cyclicity of gastric motility in rats.

The cyclicity and intensity of gastric motility were examined following glucose injection into the nucleus of the vagus nerve (X) or into the nucleus of the solitary tract (SOL) in anesthetized rats. Enhanced gastric motility caused by insulin administration was influenced by 4 mM glucose (500 nl) injected into the X; glucose provoked a shift in the cyclicity power spectrum without any change in intensity. The peak power spectrum shifted from 4.0-5.0 cpm to 2.0-3.0 cpm, but not significant change in the cyclicity power spectrum was seen when the same dose of glucose was injected into the SOL. It was also noted that the power spectrum response to 4 mM glucose injection into the X was not modified when 4 mM glucose was injected into the SOL simultaneously. The results suggest that the medullary glucose signal in the X differentially modulates the cyclicity of gastric motility independent of the SOL.