Identification of the taste cell G-protein, alpha-gustducin, in brush cells of the rat pancreatic duct system.

The major pancreatic excretory ducts have been shown to contain a large number of specialized epithelial cells, named brush cells, that are characterized by an apical tuft of stiff microvilli. The function of pancreatic brush cells is unknown. Because of some structural similarities to taste receptor cells of the tongue, we addressed the question whether pancreatic brush cells contain the taste cell-specific GTP-binding protein, alpha-gustducin, and hence might be considered to be involved in intraductal chemoreception. By immunostaining, we show that ductal brush cells of the rat pancreatic duct system contain alpha-gustducin, which is concentrated in the apical tuft of microvilli and is also found along the basolateral cell surface. A further outcome of this study is that brush cells are concentrated in the terminal portions of extralobular ducts and in the major pancreatic duct where brush cells comprise up to 22% of the ductal epithelium. Immunoblotting of the major pancreatic duct revealed a 42-kDa band that comigrated with alpha-gustducin of the rat tongue. In view of our previous observation that the ductal brush cells are particularly rich in nitric oxide synthase-I, there is reason to assume that these cells might play a role in certain aspects of chemoreceptive signalling. Thus, chemosensory control of pancreatic secretion might occur at two independent sites, the intestine and the terminal portions of the excretory duct system.