α9α10 nicotinic acetylcholine receptors regulate murine bone marrow granulocyte functions

Polymorphonuclear neutrophilic granulocytes (PMNs) are extremely important in defense of the organism against infections and in inflammatory processes including neuroinflammation and pain sensation. Different subtypes of nicotinic acetylcholine receptors (nAChRs) are involved in modulation of PMN activities. Earlier we determined expression of α2-7, α9, β3, β4 subunits and regulatory role of α7 and α3β2 nAChR subtypes in functions of inflammatory PMNs. Other authors detected mRNA of α9 subunit in bone marrow neutrophils (BM-PMNs). Murine BM-PMNs coming out from the bone marrow, where they develop, to blood were characterized as mature. There was no data for α10 and for the presence of functionally active α9α10 nAChRs in BM-PMNs. Here we detected for the first time mRNA expression of the α10 nAChR subunit in BM-PMNs and confirmed the expression of mRNA for α9 nAChR. With the help of α-conotoxins RgIA and Vc1.1, highly selective antagonists of α9α10 nAChRs, we have revealed participation of α9 and/or α9α10 nAChRs in regulation of cytosolic Ca²⁺ concentration, cell adhesion, and in generation of reactive oxygen species (ROS). Nicotine, choline, RgIA, and Vc1.1 induced Ca²⁺ transients in BM-PMNs, enhanced cell adhesiveness and decreased production of ROS indicating involvement of α9, possibly co-assembled with α10, nAChRs in the BM-PMN activity for recruitment and cytotoxicity.