Circadian periodicity of epidermal growth factor and its abolition by superior cervical ganglionectomy.

Overview

The concentration of epidermal growth factor (EGF) in mouse submaxillary gland displays a circadian variation, which can be phase-shifted by light-dark reversal, and which is abolished by superior cervical ganglionectomy (SCG). Such circadian variation persists in fasted animals. Peak concentrations occur during light hours, trough concentrations during dark, although peak concentrations in female animals occur 8 h in advance of the time when they are seen in male animals. The nocturnal fall can be reversed by a one hour exposure to light presented during the normal dark period. SCG does not abolish the increase in submaxillary gland EGF concentrations to levels characteristic of the normal male that is seen following testosterone administration to female mice (who normally exhibit much lower EGF concentrations). Plasma EGF concentrations do not exhibit a ciradian variation.