Participation of the Cholinergic System in Ameliorating Effect of Vasopressin Fragment by Group I Metabotropic Glutamate–Receptor Blockade

Abstract

Abstract. The effect of [pGlu 4 ,Cyt 6 ,Arg 8 ]-vasopressin fragment 4-9 (AVP4-9) on group I metabotropic glutamate (mGlu 1 ) receptor antagonist-induced memory deficits was studied using 8-arm radial maze performance with 4 arms baited. In addition, the participation of the cholinergic system in the ameliorating effect of AVP4-9 on mGlu 1 receptor antagonist-induced memory deficits was also investigated. Intrahippocampal injection of (R,S)-1-aminoindan-1,5-dicarboxylic acid (AIDA), an mGlu 1 -receptor antagonist, significantly increased total error, reference memory error, and working memory error at a dose of 20 nmol / side. AVP4-9 (0.1 and 1.0 μg/ kg, s.c.) showed a significant ameliorative effect on AIDA-induced memory deficits. Improvement of AIDA-induced memory deficit in response to AVP4-9 treatment was significantly antagonized by scopolamine (5 nmol / side) but not by mecamylamine (200 nmol / side) at a dose that caused no effect on performance when injected separately. These findings indicate that the ameliorating effect of AVP4-9 on AIDA-induced memory deficit may be closely associated with the muscarinic receptor.

Ameliorative Effect of a Hippocampal Metabotropic Glutamate– Receptor Agonist on Histamine H1 Receptor Antagonist–Induced Memory Deficit in Rats

“…The maze was elevated 40-cm above the floor and placed in a rectangular room that contained salient visual cues. The procedure was as follows (17,18): To familiarize rats with the radial maze, they received a once-daily habituation session for 3 days prior to training. On the first day, food pellets (45 mg each, Bio-Serv; A Holton Industries, Frenchtown, NJ, USA) were scattered over the entire maze surface, and 4 rats were simultaneously placed on the radial maze and allowed to take pellets freely.…”

Interaction between Hippocampal .GAMMA.-Aminobutyric AcidA and N-Methyl-D-aspartate Receptors in the Retention of Spatial Working Memory in Rats

“…Eight-Arm Radial Maze Task The apparatus was described in our previous paper. 14,15) First, to familiarize them with the radial maze, rats received one daily habituation session for 2 d prior to training. Food pellets (45 mg each, BioServ; A Holton Industries, Frenchtown, NJ, U.S.A.) were scattered over the entire maze surface, and 3 rats were simultaneously placed on the radial maze and allowed to take pellets freely.…”