A subtype of the metabotropic glutamate receptor family in the olfactory system of Atlantic salmon

Abstract

A plasma membrane rich fraction was prepared from olfactory rosettes of Atlantic salmon and used to study binding of l-glutamic acid and activation of phospholipase C (PLC). Glutamate binding was saturable, high affinity, and inhibited by aspartic acid and taurocholate but not by alanine and lysine. Binding of glutamate was potently inhibited by various ligands for rat brain metabotropic glutamate receptors (mGluR) and also by kainate and N-methyl- d-aspartate. Glutamate stimulated phosphatidylinositol 4,5-bisphosphate breakdown consistent with G protein-dependent activation of PLC. Northern blot analyses demonstrated the presence of olfactory rosette RNA that hybridizes with cDNA probes for mGluR1 and mGluR4 under low stringency conditions. The results indicate the salmon olfactory system includes a subtype of the metabotropic glutamate receptor family.