ACINAR AND CELLULAR-DISTRIBUTION AND MESSENGER-RNA EXPRESSION OF THE EPIDERMAL GROWTH-FACTOR RECEPTOR ARE CHANGED DURING LIVER-REGENERATION

The epidermal growth factor receptor shows acinar heterogeneity with a portal-to-central concentration gradient, Immunohistochemical analysi s showed that the strong cytoplasmic staining for epidermal growth fac tor receptor found in normal hepatocytes disappears over time after pa rtial hepatectomy or sham operation, however, with different time cour ses, Four hours after surgery, 84.3+/-3.5% (mean+/-SD) of the hepatocy tes in animals after sham operation showed strong cytoplasmic staining vs, 21.8+/-19.0% in animals after partial hepatectomy, After 12 h, th e cytoplasmic staining in animals after sham operation was further red uced to 39.0+/-22.6% vs. 20.0+/-5.5% in animals after partial hepatect omy. At the same time point, we found staining for the epidermal growt h factor receptor in nuclei of 21.8+/-14.8% and 3.0+/-3.9% of the hepa tocytes in animals after partial hepatectomy and animals after sham op eration, respectively. Northern blot analysis revealed comparable chan ges in expression of the epidermal growth factor receptor mRNA in anim als after partial hepatectomy and in animals after sham operation, No changes were evident in animals after sham operation, however, if the abdominal incisions were shortened, This suggests that at least part o f the changes found in animals with sham operation are due to acute ph ase events and/or surgical stress, In conclusion, partial hepatectomy induces changes in the intracellular and acinar fate of the epidermal growth factor receptor, drives the receptor to the nuclei, and affects the expression of the epidermal growth factor receptor mRNA.