S induces antinociception. CRD induces a volume-dependent increase of the AWR score in both fasting and fed rats (panels A and B respectively) and Na2S (100 μMol/kg i.p.) causes a significant reduction of visceral sensitivity and pain (panel C). Data are mean ± SEM of 5 rats. *p < 0.05 versus CRD. CRD induces the increase of spinal cFos expression that is downregulated by Na2S (panel D). Data are mean ± SEM of 5 rats. *p < 0.05 versus control.