Neuronal activities of CRD-excited ACC neurons in response to CRD in CCK-8 infusion rats. (A) Recording of a 50 mmHg colorectal distension (CRD)-excited ACC neuron in a control rat and a rat with CCK-8 infusion. In control rats, the responses to 50 mmHg CRD were tested twice (first test and second test) and the results showed that the responses were stable and repeatable. In CCK-8-treated group, CCK-8 infusion did not change ACC spontaneous neuronal firing and the spike firing rates in response to 50 mmHg CRD compared with saline infusion. (B) Histograph shows that the spontaneous firing of CRD-excited neurons of ACC and spike firing rates in response to CRD pressures (50 mmHg) was not changed in rats treated with CCK-8 compared with saline. Results were expressed as means ± SE. Statistical comparisons between control and CCK-8-treated rats were made by Student’s t-test.