Epidermal growth factor receptor induced Erk phosphorylation in the suprachiasmatic nucleus.

A significant functional role for epidermal growth factor receptor (EGFR) in the suprachiasmatic nucleus (SCN) is suggested by the confluence of several recent findings: (1) EGFR is highly expressed in the SCN, (2) the EGFR ligand TGFalpha is expressed and apparently locally released in the SCN, and (3) EGFR activation local to the 3rd ventricle suppresses circadian locomotor behavior and drinking/feeding activities. However, it has not yet been shown that binding of EGFR in the SCN can activate the key signaling pathways associated with its function. Here, we report that EGF treatment induced Erk1/2 phosphorylation in the rat SCN cells. The observation indicates functional EGFR in the SCN and motivates further investigation of the functional role of these receptors.