Postnatal colocalization of tyrosine hydroxylase and choline acetyltransferase in neurons of the dorsal motor nucleus of the vagus of the laboratory shrew (Suncus murinus)

We detected the transient coexistence of tyrosine hydroxylase (TH) and choline acetyltransferase (CAT) in the neurons of the dorsal motor nucleus of the vagus (DMV) and in cholinergic fibers of the myenteric plexus of the stomach of the laboratory shrew (Suncus murinus) by immunohistochemistry. The DMV neurons showed no reactivity to antiserum against GTP cyclohydrolase I, DOPA, aromatic L-amino acid decarboxylase or dopamine. After birth, the intensity of TH-immunoreactivity of the DMV neurons reached a maximum on postnatal days 7-9 and then decreased until postnatal day 20, when almost no TH-immunoreactivity was detected. These results suggest that TH may function not as a catecholamine-synthesizing enzyme but as a regulatory protein necessary for release acceleration or inhibition in the postnatal development of cholinergic neurons of the DMV.