Immunolocalization of transforming growth factor-alpha and epidermal growth factor receptor in the rat gastroduodenal area.

The maintenance of gastrointestinal epithelium integrity requires a fine balance between proliferation and differentiation as well as protection against gastric acid secretion. Transforming growth factor-alpha (TGF-alpha) regulates these functions by binding to epidermal growth factor receptor (EGF-R). This study was designed to identify the localization of TGF-alpha and EGF-R in the rat gastroduodenal region. In the stomach, the surface and gastric pit cells showed staining for TGF-alpha antibodies in the cytoplasm and basolateral and apical membranes. TGF-alpha and EGF-R were observed in the supranuclear region of the cells lining the gland. In the duodenum, the enterocytes coexpressed both TGF-alpha and EGF-R in the supranuclear area. The EGF-R was also observed in the apical membrane. Brunner's glands were positive for both TGF-alpha and EGF-R antibodies. Our results demonstrate the coexpression of TGF-alpha and EGF-R in the rat gastroduodenal area, which suggests a functional role for them in the establishment and maintenance of the epithelial renewal.