Vesicular monoamine transporter 2 expression in enteric neurons and enterochromaffin-like cells of the rat.

The cellular localization of the vesicular monoamine transporter 2 (VMAT2) in the rat digestive tract was investigated with immunohistochemistry. VMAT2-immunoreactivity (IR) was localized to neurons and fibers of enteric and pancreatic ganglia, to processes supplying the gut wall, the pancreas and blood vessels, and to enterochromaffin-like (ECL) cells 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 distribution of biogenic amine cell groups in the digestive tract. Our results provide further evidence that VMAT2 is the vesicular amine transporter responsible for accumulation of monoamines into secretory vesicles of monoaminergic neurons and ECL cells.