NOS1 and ischemia: Previous studies on two mouse models of intestinal ischemia/reperfusion and DNBS-induced (DiNitroBenzene Sulfonic acid) colitis in the enteric nervous system (ENS) showed OTX2 protein mainly expressed in neurons of the ENS in association with the neuronal isoform of nitric oxide synthase (nNOS), while OTX1 presented a glial distribution and an association with the inducible NOS [47, 48].