Cobalamin deficiency-induced changes of epidermal growth factor (EGF)-receptor expression and EGF levels in rat spinal cord

We investigated the effect of cobalamin (Cbl) deficiency on epidermal growth factor receptor (EGFR) mRNA levels in the spinal cord (SC) and liver of rats made Cbl-deficient (Cbl-D) by means of total gastrectomy or a Cbl-D diet, and simultaneously measured the levels of the epidermal growth factor (EGF). Both methods of inducing Cbl deficiency decreased EGFR expression in the SC and liver. Cbl replacement treatment normalized or nearly so most of the abnormalities in EGFR expression in the totally gastrectomized (TGX) rats at different times. The EGFR-immunostaining intensity decreased in the SC white matter of the Cbl-D rats and significantly increased in that of the TGX, Cbl-treated rats. EGF levels significantly increased in liver of TGX rats and in SC of 4-month TGX rats, and the increases returned to almost normal levels after a postoperative 2-month administration of Cbl to TGX rats. These findings demonstrate that Cbl deficiency dysregulates the EGFR-EGF dyad in these tissues.