Differential analgesic activity of the enantiomers of atropine derivatives does not correlate with their muscarinic subtype selectivity
摘要:
The enantiomers of several tropic and p-substituted tropic acid esters related to atropine obtained by esterification under non-racemizing conditions after resolution of the corresponding racemic acids [(+)- and (-)-18, (+)- and (-)-19] are reported. They were tested in vitro on muscarinic subtype receptors and in vivo for their analgesic activity on mice. As in the case of the lead compound, R-(+)-hyoscyamine, these substances show enantioselectivity in analgesic tests, the eutomers being the R-(+) or R-(+)-p-substituted tropic acid derivatives. However, this property, which is a consequence of increased central release of ACh, seems unrelated to muscarinic subtype selectivity insofar as the compounds are unable to discriminate muscarinic subtype receptors. A possible explanation of these results which does not involve subtype selectivity is proposed, based on the recently developed concept of inverse agonism.
Differential analgesic activity of the enantiomers of atropine derivatives does not correlate with their muscarinic subtype selectivity
摘要:
The enantiomers of several tropic and p-substituted tropic acid esters related to atropine obtained by esterification under non-racemizing conditions after resolution of the corresponding racemic acids [(+)- and (-)-18, (+)- and (-)-19] are reported. They were tested in vitro on muscarinic subtype receptors and in vivo for their analgesic activity on mice. As in the case of the lead compound, R-(+)-hyoscyamine, these substances show enantioselectivity in analgesic tests, the eutomers being the R-(+) or R-(+)-p-substituted tropic acid derivatives. However, this property, which is a consequence of increased central release of ACh, seems unrelated to muscarinic subtype selectivity insofar as the compounds are unable to discriminate muscarinic subtype receptors. A possible explanation of these results which does not involve subtype selectivity is proposed, based on the recently developed concept of inverse agonism.