VESICULAR MONOAMINE TRANSPORTER-2 EXPRESSION IN ENTERIC NEURONS AND ENTEROCHROMAFFIN-LIKE CELLS OF THE RAT

The cellular localization of the vesicular monoamine transporter 2 (VM AT2) in the rat digestive tract was investigated with immunohistochemi stry. VMAT2-immunoreactivity (IR) was localized to neurons and fibers of enteric and pancreatic ganglia, to processes supplying the gut wail , the pancreas and blood vessels, and to enterochromaffin-like (ECL) c ells in the gastric corpus, which contained calbindin-IR. Few VMAT2-IR cells were also found in the gastric antrum, but they did not contain gastrin-IR. VMAT2-IR was expressed in extrinsic sympathetic fibers as demonstrated by the elimination of a portion of VMAT2-IR processes by sympathectomy. The VMAT2-IR pattern is consistent with the overall di stribution of biogenic amine cell groups in the digestive tract. Our r esults provide further evidence that VMAT2 is the vesicular amine tran sporter responsible for accumulation of monoamines into secretory vesi cles of monoaminergic neurons and ECL cells.