Although other sources of NPY cannot be excluded, elevated levels of plasma NPY are likely to reflect increased release of the neuropeptide from sympathetic nerve endings (Bloom et al., 1988; Zukowska-Grojec, 1995; Renshaw and Hinson, 2001), a conclusion that is consistent with other data that colitis is associated with increased sympathetic activity (Ganguli et al., 2007; Xia et al., 2011). Here, NPY is linked to colitis.