• Metabotropic glutamate receptors;
  • submucous plexus;
  • enteric nervous system;
  • small intestine;
  • intestinal secretion

Intracellular recording methods and immunostaining revealed the existence of functional group I metabotropic glutamate receptors (mGluRs) in submucous plexus neurons of guinea-pig ileum. Selective group I, but not groups II or III metabotropic glutamate receptor agonists induced concentration-dependent, slowly-activating depolarizing responses. Group I metabotropic glutamate receptor antagonism observed with (S)-4-carboxyphenylglycine (S-4-CPG) (100–600 μM) was competitive as determined by Schild analysis (pA2=3.81±0.02). Neither the group II and III metabotropic nor ionotropic glutamate receptor antagonists altered responses evoked by group I receptor agonists. Immunoreactivities for metabotropic glutamate 1α and 5 receptors were found to locate exclusively in neurons in the submucous plexus of guinea-pig ileum with the highest density around the cell bodies. The results suggest that group I metabotropic glutamate receptors are functionally expressed in the submucous plexus of guinea-pig small intestine.

British Journal of Pharmacology (1999) 128, 1631–1635; doi:10.1038/sj.bjp.0702980