The ontogeny of induction of c-fos in the rat SCN by a 5-HT2A/2C agonist

The induction of c-fos in the suprachiasmatic nucleus (SCN) by the 5-HT2A/2 C agonist, DOI was studied at mid-dark in neonatal rats. The number of cell s expressing c-FOS immunoreactivity following DOI was low 3 days after birt h, but increased rapidly over the next 3 days. By contrast, light exposure stimulated cells throughout this period. These results are consistent with the arrival of serotonergic afferents at the SCN and their role in the entr ainment of rhythms. (C) 2000 Elsevier Science B.V. All rights reserved.