Peripheral peptide YY induces c-fos-like immunoreactivity in the rat brain

The influence of peripheral injection of peptide YY (PYY) on neuronal activity in the rat brain was examined by immunohistochemical detection of c-fos protein. Numerous c-fos-immunoreactive nuclei were found in the area postrema, nucleus tractus solitarius (commissural and medial subnuclei), central amygdala and thalamus (periventricular and medial) of rats injected i.p. with PYY at a dose of 300 micrograms/kg. c-fos-like immunoreactivity was found to be less when lower doses of PYY (50-200 micrograms/kg, i.p.) were injected. Either no or few cells were detected after i.p. injection of the vehicle alone. These data provide anatomical support for the centrally mediated actions of peripheral PYY on gut function.