Muscarinic acetylcholine receptors in bulk-isolated astrocytes of the hippocampus in the rat.
The high-affinity muscarinic antagonist L-[3H]quinuclidinyl benzi-late (L-[3H]QNB) was used to label muscarinic acetylcholine receptors in the astrocyte-enriched fraction isolated from rat hippocampus. Analysis of the saturation and drug inhibition data showed that [3H]QNB binding in the astroglia fraction was saturable, of high affinity (Kd = 0.026 nM) and competitively inhibited by muscarinic antagonists and agonists. The Kd for [3H]QNB binding sites in the astroglia fraction was similar to that found for muscarinic receptors in the hippocampal homogenate and in the hippocampal synaptic plasma membranes. The density of [3H]QNB binding sites in the bulk-isolated astroglia fraction (Bmax =0.852 pmol/mg protein) was, however, much lower than that in the hippocampal synaptic plasma membranes (Bmax equal to about 2 pmol/mg protein). The results suggest that hippocampal astrocytes possess specific [3H]QNB binding sites with receptor binding characteristics of neuronal muscarinic acetylcholine receptor.
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D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D002469:Cell Separation; D006624:Hippocampus / Q000166:cytology* / Q000378:metabolism; D007700:Kinetics; D008297:Male; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000378:metabolism*
D011976:Receptors, Muscarinic; D011813:Quinuclidinyl Benzilate