Muscarinic Receptor Subtypes as Potential Targets to Modulate Oligodendrocyte Progenitor Survival, Proliferation, and Differentiation Federica De Angelis, 1 Antonietta Bernardo, 2 Valerio Magnaghi, 3 Luisa Minghetti, 2 Ada Maria Tata 1 1 Department of Biology and Biotechnologies Charles Darwin, Center of Neurobiology Research Daniel Bovet, La Sapienza University of Rome, Rome, Italy 2 Department of Cell Biology and Neurosciences, ISS, Rome, Italy 3 Department of Endocrinology, Physiopathology and Applied Biology, University of Milan, Italy Received 27 May 2011; revised 6 August 2011; accepted 6 September 2011 ABSTRACT: Acetylcholine (ACh) is a major neurotransmitter but also an important signaling mole- cule in neuron-glia interactions. Expression of ACh receptors has been reported in several glial cell popula- tions, including oligodendrocytes (OLs). Nonetheless, the characterization of muscarinic receptors in these cells, as well as the description of the cholinergic effects at different stages of OL development, is still incom- plete. In this study, we characterized the pattern of expression of muscarinic receptor subtypes in primary cultures of rat oligodendrocyte progenitor cells (OPC) and mature OLs, at both mRNA and protein levels. We found that muscarinic receptor expression is develop- mentally regulated. M1, M3, and M4 receptors were the main subtypes expressed in OPC, whereas all receptor subtypes were expressed at low levels in mature OLs. Exposure of OPC to muscarine enhanced cell prolifera- tion, an effect mainly due to M1, M3, and M4 receptor subtypes as demonstrated by pharmacological competi- tion with selective antagonists. Conversely, M2 receptor activation impaired OPC survival. In line with the mito- genic activity, muscarinic receptor activation increased the expression of platelet derived growth factor receptor a. Muscarine stimulation increased CX32 and myelin basic protein expression, left unaffected that of myelin proteolipid protein (PLP), and decreased member of the family of epidermal growth factor receptor (EGFR) ErbB3/ErbB4 receptor expression indicating a predomi- nant role of muscarinic receptors in OPC. These find- ings suggest that ACh may contribute to the mainte- nance of an immature proliferating progenitor pool and impair the progression toward mature stage. This hy- pothesis is further supported by increased expression of Notch-1 in OL on muscarinic activation. ' 2011 Wiley Periodicals, Inc. Develop Neurobiol 72: 713–728, 2012 Keywords: muscarinic receptors; oligodendrocytes; proliferation; survival; myelin proteins INTRODUCTION During nervous system development, neuron-glia interactions modulate several processes, including neural stem cell proliferation (Ma et al., 2004; Zhou et al., 2004) neurite extension and fiber myelination (Barres, 1997), synapse formation (Pfrieger et al., 1997) and neuron migration (Anton et al., 1997), and differentiation (Garcia-Abreu et al., 1995). Several Additional Supporting Information may be found in the online version of this article. Federica De Angelis and Antonietta Bernardo contributed equally to this work. Correspondence to: A.M. Tata (adamaria.tata@uniroma1.it). Contract grant sponsor: University La Sapienza and Istituto Superiore di Sanita ` funds. Contract grant sponsor: Centro di Eccellenza di Biologia e Medicina Molecolare (BEMM). ' 2011 Wiley Periodicals, Inc. Published online 12 September 2011 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/dneu.20976 713