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Castration decreases amylase release associated with muscarinic acetylcholine receptor downregulation in rat parotid gland
Author(s) -
Busch Lucila,
Borda Enri
Publication year - 2003
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 - 10.1038/sj.bjp.0705260
Subject(s) - carbachol , pirenzepine , muscarinic acetylcholine receptor , endocrinology , medicine , muscarinic acetylcholine receptor m3 , muscarinic acetylcholine receptor m2 , chemistry , muscarinic acetylcholine receptor m1 , population , acetylcholine , biology , receptor , environmental health
The mechanism and receptor subtypes involved in carbachol‐stimulated amylase release and its changes after castration were studied in parotid slices from male rats. Carbachol induced both amylase release and inositol phosphate (IP) accumulation in parotid slices from control and castrated rats, but castration induced a decrease of carbachol maximal effect. The effect of castration was reverted by testosterone replacement. The selective M 1 and M 3 muscarinic receptor antagonists, pirenzepine and 4‐diphenylacetoxy‐ N ‐methylpiperidine methiodide, respectively, inhibited carbachol‐stimulated amylase release and IP accumulation in a dose‐dependent manner in parotid slices from control and castrated rats. A diminution of binding sites of muscarinic receptor in parotid membrane from castrated rats was observed. Competition binding assays showed that both, M 1 and M 3 muscarinic receptor subtypes are expressed in membranes of parotid glands from control and castrated rats, M 3 being the greater population. These results suggest that amylase release induced by carbachol in parotid slices is mediated by phosphoinositide accumulation. This mechanism appears to be triggered by the activation of M 1 and M 3 muscarinic receptor subtypes. Castration induced a decrease of the maximal effect of carbachol evoked amylase release and IP accumulation followed by a diminution in the number of parotid gland muscarinic acetylcholine receptors.British Journal of Pharmacology (2003) 139 , 399–407. doi: 10.1038/sj.bjp.0705260