Differential distribution of transforming growth factor-a immunohistochemistry within whole gastric mucosa in rats

Transforming growth factor-a (TGF-a) plays an important role in both proliferation and differentiation of mucosal cells at the gastrointestinal level, including stomach, where it is constitutively produced. This study evaluated the immunohistochemical distribution of TGF-a within whole gastric mucosa in rats, through the examination of seriate sections. Each stomach was opened along the greater curvature, pinned upon a cork plate, fixed in formalin and cut in 2-mm parallel strips which were sequentially superimposed on a glass slide. Sections were immunostained for TGF-a and pictures were taken from three areas: greater and lesser curvature; mucosa lying between the two curvatures. The sections were graded on the basis of the intensity of TGF-a staining, which was scored as follows: 0) no staining; 1) weakly positive; 2) intensely positive. The percent number of immunopositive cells and a mean intensity were calculated. Gastric mucosa showed a marked immunopositivity to TGF-a, mainly in parietal cells whose cytoplasm displayed moderate to intense staining. Positive cells (and the mean intensity) of total mucosa were 15.7±6.1% (1.13±0.42). However, they were not uniformly distributed, being 26.3±1.9% (1.67±0.24) in the mucosa lying between the two curvatures, 12.4±2.5% (1.52±0.22) along the lesser curvature and 8.3±2.1% (0.31±0.17) along the greater curvature. These results show that parietal cells of rat gastric mucosa exhibit immunoreactivity to TGF-a. Considering the gastroprotective effects of this factor, its non-homogeneous distribution within different areas may be of importance in understanding the lesion pattern of gastric damage after the administration of noxious agents.