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EVIDENCE FOR THE PHARMACOLOGICAL SIMILARITY BETWEEN THE CENTRAL PRESYNAPTIC MUSCARINIC AUTORECEPTOR AND POSTSYNAPTIC MUSCARINIC RECEPTORS
Author(s) -
BOWEN D.M.,
MAREK K.L.
Publication year - 1982
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1982.tb08795.x
Subject(s) - autoreceptor , muscarinic acetylcholine receptor , postsynaptic potential , muscarinic acetylcholine receptor m4 , chemistry , muscarinic acetylcholine receptor m2 , endocrinology , muscarinic acetylcholine receptor m1 , medicine , atropine , muscarinic antagonist , acetylcholine , stimulation , agonist , muscarinic acetylcholine receptor m3 , pharmacology , receptor , biology , biochemistry
1 Twenty antagonist substances with varying potencies for central and peripheral postsynaptic muscarinic receptors have been examined for effects on the central presynaptic muscarinic autoreceptor. This has been monitored by measuring the stimulating effects of the substances on acetylcholine synthesis by rat neocortical tissue prisms. 2 Dose‐response curves for selected agents showed that maximal stimulation of synthesis was to 136–140% of the value without an antagonist. 3 At a concentration of 1 μ m , 17 of the substances caused a significant increase in synthesis, whilst at 0.01 μ m significant stimulation occurred with only atropine, dexetimide, N‐methyl‐piperdin‐4‐yl (R)‐2‐cyclohexyl‐2‐hydroxyl‐2‐phenylacetate, quinuclidinyl benzilate (QNB) and scopolamine. 4 Linear regression analysis between synthesis values obtained with the substances and published data for the effects on either cholinoceptor‐agonist induced contraction of guinea‐pig ileum or the binding of [ 3 H]‐QNB to rat forebrain membranes gave correlation coefficients of r = 0.84 ( P <0.01), and r = 0.75 ( P <0.02) respectively. 5 The results provide no indication of a pharmacological difference between the central presynaptic muscarinic autoreceptor and central and peripheral postsynaptic muscarinic receptors.