NON-PHOTIC MANIPULATIONS INDUCE EXPRESSION OF FOS PROTEIN IN THE SUPRACHIASMATIC NUCLEUS AND INTERGENICULATE LEAFLET IN THE RAT

Expression of Fos protein in the suprachiasmatic nucleus (SCN) and int ergeniculate leaflet (IGL) is considered a cellular correlate of light -induced phase-shift of circadian rhythms in rodents. Non-photic stimu li also induce phase shifts, but their effects on Fos expression have not been established. We examined induction of Fos protein in SCN and IGL regions, in response to cage change, intraperitoneal saline inject ion, and restraint stress. Fos immunoreactivity was observed in SCN an d IGL regions, with greater expression observed in IGL during the ligh t phase of the light-dark cycle. Results suggest that cells in SCN and IGL respond to several types of non-photic manipulations and that exp ression of Fos in these regions is not light-specific.