Stereoisomerism and muscarinic receptor agonists: Synthesis and effects of the stereoisomers of 3-[5-(3-amino-1,2,4-oxadizol)yl]-1-azabicyclo[2.2.1]heptane

E. Pombo-Villar, K.-H. Wiederhold, G. Mengod, J.M. Palacios, P. Supavilai, H.W.G.M. Boddeke

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The preparation and the biological activities of the four stereoisomers of 3-[5-(3-amino-1,2,5-oxadiazol)yl]-1-azabicyclo [2.2.1]heptane are described. The most potent stereoisomer, 3a, has the 3R,4R configuration, and in vitro activities in (pD2(% efficacy): ileum 8.8 (87%), hippocampus 9.8 (116%) and ganglion 10.2 (36%)). 3b (3S,4S) was weaker (ileum 8.1 (121%), hippocampus 8.5 (107%), ganglion 9.0 (63%)). The other two stereoisomers, 4a (3S,4R; ileum 7.1 (108%), hippocampus 8.2 (116%), ganglion 7.3 (31%)) and 4b (3R,4S; ileum 7.0 (100%), hippocampus 7.0 (120%), ganglion 7.2 (67%)) are of comparable activity, with an analogous profile to that of the more potent stereoisomers. Thus, compounds 3a and 4a, possessing the 4R stereochemistry, showed selectivity for the hippocampus over the ileum. Compound 3a was, however, more potent in the ganglion than in the hippocampus. All four stereoisomers were full agonists in the hippocampus, indicating M1activity; however, they were partial agonists in the depolarisation of the rat superior cervical ganglion, another M1-mediated response. This may be due to M2-mediated hyperpolarization. With 3a (0.01 mg/kg i.p.), expression of c-fos mRNA was observed in the hypothalamus and in brain areas involved in sensory processing; these effects were totally blocked by pretreatment with 2 mg/kg scopolamine. In particular, activation of the superior colliculus is consistent with potent M2activity.
Original languageEnglish
Pages (from-to)317-325
Number of pages9
JournalEuropean journal of pharmacology-Molecular pharmacology section
Issue number4
Publication statusPublished - 12-Nov-1992


  • c-fos expression
  • Hippocampal slice (Rat)
  • Hybridization in situ
  • Ileum (guinea pig)
  • Muscarinic receptor agonists
  • Muscarinic receptor subtypes
  • Stereochemistry (absolute)
  • Superior cervical ganglion (rat)
  • 1,3 dioxolane derivative
  • 3 (3 amino 1,2,4 oxadiazol 5 yl) 1 azabicyclo[2.2.1]heptane
  • carbachol
  • messenger RNA
  • muscarinic agent
  • muscarinic M1 receptor
  • muscarinic M2 receptor
  • muscarinic receptor
  • pirenzepine
  • radioligand
  • unclassified drug
  • animal experiment
  • animal tissue
  • article
  • controlled study
  • drug potency
  • drug selectivity
  • drug synthesis
  • gene expression
  • hippocampus
  • ileum
  • in situ hybridization
  • intraperitoneal drug administration
  • male
  • nonhuman
  • oncogene c fos
  • priority journal
  • rat
  • stereoisomerism
  • superior cervical ganglion

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