Glucagon-like peptide-1 modulates neuronal activity in the rat's hippocampus

IN order to assess effects of glucagon-like peptide-1 (GLP-1) in the brain excluding the hypothalamus, the effects of GLP-1 (7-36) amide, a naturally produced active fragment, on the electroencephalogram and hippocampal singl e unit activities of anesthetized male Wistar rats were examined. I.c.v. in jection of GLP-1 (7-36) amide decreased the hippocampal theta wave duration . Juxtacellular administration of GLP-1 (7-36) amide first increased and th en decreased single unit activities recorded in the hippocampal CA1, which effects were antagonized by exendin (9-39) amide, a GLP-1 receptor antagoni st, or 6-cyano-7-nitroquinoxaline-2,3-dione, a non-NMDA type glutamate rece ptor antagonist. These results indicate that GLP-1 receptors exist in the h ippocampus and are involved in modulating hippocampal activity through an i ncrease in the release of excitatory amino acid transmitters. NeuroReport 1 0:1643-1646 (C) 1999 Lippincott Williams & Wilkins.