PLC beta 4-independent Ca2+ rise via muscarinic receptors in the mouse suprachiasmatic nucleus

Cholinergic regulation of the suprachiasmatic nucleus (SCN) has been extens ively studied although the intracellular signaling mechanisms are not well understood. We examined immunostaining for phospholipase C-beta (PLC-beta) families that couple to muscarinic acetylcholine receptors (mAChR) and demo nstrated the expression of PLC-beta 1 and beta 4 in the mouse SCN. Ca2+ ima ging analysis indicated that the MI-mAChR antagonist, pirenzepine blocked c arbachol-induced Ca2+ elevation in the SCN and the response was equivalent between the wild type and the PLC-beta 4-knockout mice. In addition. the kn ockout mice displayed locomotor and temperature rhythms coupling to 24 h li ght/dark cycles. Therefore, it was proposed that PLC-beta 1 but not PLC-bet a 4 was involved in the mAChR-mediated Ca2+ signaling in the SCN. NeoroRepo rt 11:907-912 (C) 2000 Lippincott Williams & Wilkins.