CHOLINERGIC AGONISTS INCREASE INTRACELLULAR CA2+ IN CULTURED HUMAN MICROGLIA

Microglia are resident phagocytic cells in the central nervous system (CNS), and can be activated in response to various stimuli including n eurotransmitters. Using fura-2 imaging, we investigated the effects of carbachol (CCh), a cholinergic agonist, on [Ca2+](i) in cultured huma n microglia. Treatment of microglia with CCh (100 mu M) produced a tra nsient increase in [Ca2+](i), which was atropine-sensitive and was ass ociated with release from intracellular Ca2+ stores. Successive applic ations of CCh showed a change in the amplitude of the [Ca2+](i) signal consistent with desensitization. These results show that human microg lia express functional muscarinic receptors and respond to cholinergic agonists. The rapid change of [Ca2+](i) in microglia may serve as a s econd messenger to trigger downstream cascades which contribute to sig nalling pathways in CNS pathology. (C) 1998 Elsevier Science Ireland L td. All rights reserved.