In the present study we investigated the effects of norepinephrine and vasoactive intestinal peptide on the intracellular calcium concentration ([Ca2+]i) and on phosphorylation of the transcription factor CREB in isolated rat pinealocytes. Norepinephrine evoked a biphasic calcium response via activation of α1-adrenergic receptors in virtually all pinealocytes identified by the S-antigen immunoreaction. This response involved mobilization of calcium from intracellular calcium stores and calcium influx into the cell. Moreover, norepinephrine induced phosphorylation of CREB via activation of β-adrenergic receptors. In contrast, vasoactive intestinal peptide did not cause an elevation of [Ca2+]i, but induced pCREB immunoreactivity in a subpopulation of the pinealocytes, suggesting their functional heterogeneity.