A SUBTYPE OF THE METABOTROPIC GLUTAMATE-RECEPTOR FAMILY IN THE OLFACTORY SYSTEM OF ATLANTIC SALMON

A plasma membrane rich fraction was prepared from olfactory rosettes o f Atlantic salmon and used to study binding of L-glutamic acid and act ivation of phospholipase C (PLC). Glutamate binding was saturable, hig h affinity, and inhibited by aspartic acid and taurocholate but not by alanine and lysine. Binding of glutamate was potently inhibited by va rious ligands for rat brain metabotropic glutamate receptors (mGluR) a nd also by kainate and N-methyl-D-aspartate. Glutamate stimulated phos phatidylinositol 4,5-bisphosphate breakdown consistent with G protein- dependent activation of PLC. Northern blot analyses demonstrated the p resence of olfactory rosette RNA that hybridizes with cDNA probes for mGluR1 and mGluR4 under low stringency conditions. The results indicat e the salmon olfactory system includes a subtype of the metabotropic g lutamate receptor family.