Neuronal nicotinic acetylcholine receptor expression by O2A/Oligodendrocyte progenitor cells

Oligodendrocyte precursor cells (O2A/OPC, A2B5(+)) were examined for expres sion of neuronal nicotinic acetylcholine receptors (nAChR). RT-PCR analysis and immunocytochemistry of O2A/OPCs purified from the rat corpus collusum revealed the expression of nAChR subunits (alpha3,alpha4, alpha5, alpha7, b eta2, and beta4. Immunoreactivity toward nAChR subunits was not detected in cells induced to differentiate into either oligodendrocytes or astrocytes. Approximately 65% of O2A/OPCs loaded with the calcium-responsive dye FURA- 2 increased their intracellular free calcium in response to nicotine applic ation. This response was sensitive to the nAChR alpha4/beta2 antagonist, di hydro-beta -erythroidine (DH betaE), and the voltage-gated calcium channel antagonist, nifedipine. A subset of nicotine-responsive cells (37%) establi shed DH betaE or nifedipine-sensitive intracellular free calcium oscillatio ns that continued in the presence of nicotine. Typical oscillations occurre d at intervals of 20 to 30 s with progressively diminished amplitudes over a period of 2 to 3 min. In rare cases, oscillations persisted for as long a s 10 min. O2A/OPCs exposed to carbachol or AMPA produced no oscillations de spite robust increases in intracellular free calcium. The expression of nAC hRs in non-neuronal glial precursor cells suggests an expanded role for thi s receptor system in the development of the mammalian brain. GLIA 33:306-31 3, 2001. Published 2001 Wiley-Liss, Inc.(+)