Nicotinic acetylcholine receptor subtypes in rat superior cervical ganglion neurons as studied by sequential application of two alpha -subunit-specific antibodies

All cultured neurons of rat superior cervical ganglion (SCG) were stained with nicotinic acetylcholine receptor (nAChR) alpha 5- or alpha 7-subunit-specific oligoclonal antibodies (Abs) and could additionally bind alpha 3-subunit-specific monoclonal antibody (mAb). About 60% of the neurons were stained with alpha 4-specific Ab and could not bind alpha 3-specific mAb. The acetylcholine-induced membrane currents recorded with the whole-cell patch clamp method and partially blocked with alpha 3-specific mAbs, could be additionally blocked with alpha 5- and alpha 7-specific Abs, and vice versa. The results suggest that: (1) each neuron of rat SCG expresses several nAChR subtypes with different alpha -subunits; (2) the alpha 3-, alpha 5- and alpha 7- subunit-containing nAChRs are probably located far enough from each other thus enabling joint binding to the cell of the corresponding alpha -subunit specific Abs, in contrast to the alpha 4-subunit-containing nAChRs which are probably located too close to the alpha 3-containing ones to allow their joint binding.