THE ENDOZEPINE ODN STIMULATES POLYPHOSPHOINOSITIDE METABOLISM IN RAT ASTROCYTES

Astrocytes synthesize a series of peptides called endozepines which ac t as endogenous ligands of benzodiazepine receptors. The present study demonstrates that the endozepine ODN causes a dose-dependent increase in inositol trisphosphate and a parallel decrease in phosphatidylinos itol bisphosphate in cultured rat astrocytes, Pre-incubation of astroc ytes with the phospholipase C inhibitor U 73122 or with pertussis toxi n totally blocked polyphosphoinositide metabolism. These data show tha t, in rat astrocytes, ODN stimulates a phospholipase C coupled to a pe rtussis toxin-sensitive G protein.