Cholecystokinin-8 activates myenteric neurons in 21- and 35-day old but not 4- and 14-day old rats

▶ Cholecystokinin (CCK) activates the myenteric neurons in rats. ▶ We determined the ontogeny of this activation. ▶ CCK activated myenteric neurons of 21- and 35-day old rats but not 4 and 14. ▶ CCK activated the dorsal vagal complex of all age groups. ▶ This delayed activation reflects a delayed role for these neurons.