Distribution and colocalization of nitric oxide synthase and calretinin inmyenteric neurons of developing, aging, and Crohn's disease human small intestine

The pattern of distribution and colocalization of nitric oxide synthase and the calcium-binding protein calretinin in myenteric neurons and nerve fibe rs were examined in the human small intestine from preterm fetuses (14-17 w eeks of gestation), normal adults (mean age 50 years old), old age (mean ag e 80 years old), and Crohn's disease patients (mean age 30 years old) using NADPH-diaphorase histochemistry and immunohistochemical techniques. In all age groups investigated, NADPH-diaphorase-reactive and calretinin-immunore active neurons and nerve fibers were seen throughout the myenteric plexus. The highest proportion of NADPH-diaphorase-reactive neurons was found in th e myenteric ganglia of old age intestines (56% of protein gene product-immu noreactive neurons) followed by fetal intestines (41%) and Crohn's intestin e (30%) compared with intestines of control adults (20%). A similar trend w as observed for calretinin-immunoreactive neurons where the highest proport ion of immunoreactive neurons was found in the myenteric ganglia of old age intestines (28% of protein gene product-immunoreactive neurons), followed by fetal intestines (22%), and Crohn's intestines (18%) compared with intes tines of control adults (9%). A colocalization of NADPH-diaphorase activity and calretinin immunoreactivity was only seen in the myenteric neurons of fetal intestines (2% of NADPH-diaphorase-reactive neurons were also calreti nin-immunoreactive). The pattern of distribution of NADPH-reactive and calr etinin immunoreactive neurons in the myenteric ganglia of fetal intestine d iffers from that of the other age groups. In the fetal intestine, the myent eric neurons containing either calretinin or NADPH-diaphorase are distribut ed through out the myenteric ganglia with no specific orientation to one an other. In the intestines of control adult, Crohn's, and old age patients, s ingle large calretinin-immunoreactive neurons are surrounded by a number of small NADPH-diaphorase-positive neurons, with this feature being more prom inent in intestines of old-age and Crohn's disease patients. In summary, a high number of both NADPH-diaphorase-reactive and calretinin-immunoreactive neurons were seen in the myenteric ganglia of fetal, old age, and Crohn's intestines; we discuss that there may be a role for nitric oxide and calret inin in the process of development, aging, and pathological changes in the human intestine associated with alteration in the calcium homeostasis in th e myenteric neurons.