Immunohistochemical localisation of EGF receptors in the intestinal tract of growing rabbits in relation to age

SummaryDuring postnatal development, the intestinal tract of newborns is exposed to morphological and functional alterations. Adaptive changes are being modulated to a great extent by biologically active substances secreted from milk, such as the epidermal growth factor (EGF). The aim of the present study was to establish by a comparative approach the distribution of receptors for EGF (EGFR and ErbB-1) expressed in epithelial cells lining the villi, crypts and serosa of the duodenum, ileum, caecum and colon of rabbits euthanised at the 21st (group A) and the 35th (group B) postnatal days.The intensity of immunohistochemical staining against EGFR on the villi surface in group A was higher than that of group B in the duodenum (2.8 ± 0.11 vs. 2.0 ± 0.17; P < 0.001), ileum (2.8 ± 0.13 vs. 2.0 ± 0.21; P < 0.01) and colon (1.9 ± 0.15 vs. 1.0 ± 0.12; P < 0.05). In contrast, the luminal surface epithelial cells in the caecum of the 21-day rabbits had lower intensity of staining than in the 35-day ones (0.9 ± 0.15 vs. 2.1 ± 0.15; P < 0.001). The intensity of the immunohistochemical reaction on the surface of the villi in both groups lessened from the proximal to the distal part of the intestinal tract.The EGFR reaction occurred in a narrow range of intensities in the crypts of all investigated segments of the intestines (0.9-1.2). In general, the lowest (0.7 ± 0.14) reaction was established in the serosa of the colon of 21-day-old animals.The age-dependent presence of EGFR observed indicated that this factor should be considered when defining the optimal weaning age of the rabbit.