Noradrenaline activates vasopressin neurons via alpha(1)-receptor-mediated Ca2+ signaling pathway

Noradrenaline (Nn) (1-10 mu M), dibutyryl-cAMP (1-5 mM), and forskolin (10-20 mu M) increased cytosolic Ca2+ concentration ([Ca2+](i)) in isolated arginine-vasopressin (AVP)-containing neurons in the hypothalamic supraoptic nucleus (SON). The NA-induced increase in [Ca2+](i) in AVP-containing neurons was abolished by a specific alpha(1)-antagonist, prazosin (1 mu M) and was markedly reduced when treated with a protein kinase A (PKA) blocker, H89 (40 mu M). The NA-induced [Ca2+](i) was not altered by a protein kinase C (PKC) inhibitor, calphostin C (0.1 mu M) and a PKC activator, TPA (100 nM). In general, NA, a known neurotransmitter the SON, activates AVP-containing neurons via alpha(1)-receptor which is linked to stimulation of cAMP-PKA-regulated Ca2+ signaling pathway. (C) 1997 Elsevier Science Ireland Ltd.