Effects of secretin on neuronal activity and feeding behavior in central amygdala of rats.

Previous studies have shown that secretin and secretin receptors are expressed in central amygdala neurons. By using both in vivo extracellular recording as well as behavioral test, we investigated the direct electrophysiological effects of secretin in the central amygdala and its involvement in feeding behavior. Micro-pressure ejection of secretin increased the spontaneous firing rate by 104.22±26.18% in 13 out of the 27 central amygdala neurons. In other 6 out of the 27 neurons, secretin decreased the firing rate by 68.80±12.10%. Firing patter analysis showed that secretin did not change the firing pattern significantly. Further electrophysiological recordings revealed that secretin decreased the firing rate of glucose-sensitive neurons. In behavioral test, microinjection of secretin into the central amygdala significantly reduced cumulative food intake through cAMP-activated protein kinase activation. Based on the present electrophysiological and behavioral findings, we hypothesized that secretin may suppress food intake by its modulation of spontaneous firing of central amygdala neurons.