Involvement of sympathetic function in the sleep-related change of gastric myoelectrical activity in rats

The gastric myoelectrical activity (GMA) fluctuates across sleep-wake states as a result of modulation by the brain-gut axis. The role of the autonomic nervous system in this phenomenon, however, was not elucidated fully. Through simultaneous recording and subsequent continuous power spectral analysis of electroencephalogram, electromyogram, electrocardiogram and electrogastromyogram (EGMG) in 16 freely moving Wistar rats, the sleep-wake states of the animals were defined and indices of cardiac autonomic regulation and GMA were calculated. We found that both cardiac autonomic regulation and GMA fluctuated through sleep-wake cycles. Correlation analysis further revealed significant correlations between EGMG power and each of the R-R interval, high-frequency power, low-frequency power, very-low-frequency power, low-frequency power to high-frequency power ratio and normalized low-frequency power of heart rate variability with respect to their trend of change across different sleep-wake states. These results suggest that the sleep-wake-related change of GMA was related to sympathovagal balance. The sympathetic nerve may play a more important role in the central modulation of GMA than perceived previously.