A sed of conformationally restricted compounds containing the 4, 5, 6, 7-tetrahydroi0 [4, 5-c] pyridin-3-01 (THPO) skeleton, including 0-methyl-THPO (loa) and 0, 5-dimethyl-THPO (1 la), were synthesized. The compounds were designed by bioisosteric replacement of the methyl ester groups of the muscarinic cholinergic agonists norarecoline and arecoline by the 3- methoxyisoxazole group, and their interactions with central and peripheral muscarinic ...