Periventricular anteroventral third ventricle lesions diminish the pressorresponse produced by systemic injection of the N-methyl-D-aspartate receptor antagonist MK-801

This study examined whether electrolytic ablation of the periventricular an teroventral third ventricle (AV3V) would affect the increases in mean arter ial blood pressure (MAP) and heart rate (HR) in conscious rats produced by systemic injection of the centrally acting N-methyl-D-aspartate (NMDA) rece ptor ion-channel blocker, (+)5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohep ten-5,10-imine (MK-801; 250 mu g/kg, i.v.). MK-801 produced a smaller incre ase in MAP in rats with AV3V lesions than in sham-lesion rats (+36 +/- 2% v s. +52 +/- 5%, respectively, P < 0.05). in contrast, MK-801 produced simila r increases in HR in the AV3V- and sham-lesion rats (+28 +/- 3% vs. +22 +/- 4%, respectively, P > 0.05). These findings demonstrate that the MK-801-in duced presser response is dependent upon the integrity of the AV3V region, whereas the MK-801-induced tachycardia is not. (C) 1999 Elsevier Science B. V. All rights reserved.