2,3,7,8-Tetrachlorodibenzo-p-Dioxin Causes an Increase in Protein Kinases Growth Hepatic Associated with Epidermal Factor Receptor in the Plasma Membrane

The study investigated the effects of 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) on male rats, finding that a single dose of 25 μg/kg led to the down-regulation of epidermal growth factor (EGF) receptors in the liver's plasma membrane, starting two days post-administration and lasting for 20 days. This down-regulation was associated with increased protein kinase activity, particularly protein tyrosine kinase. Despite these changes, no differences were observed in the levels of EGF or related substances in serum samples. In mouse neonates, TCDD exposure resulted in early eye opening, tooth eruption, and poor body weight gain and hair growth, similar to effects seen with external EGF administration. The study suggested that TCDD's impact on the EGF receptor is mediated through the cytosolic/nuclear TCDD receptor, regulated by the Ah locus, and highlighted the toxicological significance of these findings.