Journal of neurochemistry
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Journal of neurochemistry · Sep 1996
Effects of steroid exposure on ligand binding and functional activities of diverse nicotinic acetylcholine receptor subtypes.
Nicotinic acetylcholine receptors (nAChR) are diverse members of the ligand-gated ion channel superfamily of neurotransmitter receptors and play critical roles in chemical signaling throughout the nervous system. The present study tests whether nAChR are potential targets for steroids. Acute or short-term (5 min) preexposure to steroids such as progesterone (which acts most potently), estradiol, corticosterone, or dexamethasone inhibits function of human muscle-type (alpha 1 beta 1 gamma delta) or ganglionic (alpha 3 beta 4) nAChR measured using 86Rb+ efflux assays in TE671/RD clonal or SH-SY5Y neuroblastoma cells. ⋯ Chronic (48 h) exposure to progesterone or estradiol, but not the other steroids, also produces blockade of nAChR function, without significant effects on numbers of nAChR radioligand-binding sites. Collectively, these results suggest that steroids act noncompetitively at extracellular sites to inhibit nAChR function with unique potencies for different steroid-nAChR subtype combinations. Thus, nAChR could be among the targets mediating physiologically relevant effects of steroid action in the nervous system.