Central Histaminergic System Mediates Prostaglandin Cascade Induced Cardiovascular Effects

Abstract

Previously, we showed that central injection of melittin, a phospholipase A2 activator, arachidonic acid (AA) or U‐46619, a thromboxane A2 analog, caused pressor effects. Moreover centrally injected histamine leads to pressor response by activating central histamine receptors. In the present study, it was aimed to demonstrate interaction between central prostaglandinergic and histaminergic system on central regulation of cardiovascular system by activating prostaglandin cascade with central administration of melittin or AA.Experiments were performed in male Spraque Dawley rats. Intracerebroventricularly (i.c.v.) injected melittin or AA caused dose‐ and time‐dependent increases in mean arterial pressure (MAP) and decrease in heart rate (HR) as we reported previously. Also, melittin or AA accompanied by 28 % or 56 % increase in extracellular histamine concentration in the posterior hypothalamus, respectively as shown in microdialysis studies. Moreover, H2 receptor antagonist ranitidine almost completely and H3/H4 receptor antagonist thioperamide partly blocked melittin‐evoked cardiovascular effects, whereas H1 receptor blocker chlorpheniramine had no effect.In conclusion, obtained first data show that there is an interaction between central histaminergic and prostaglandin cascade to central regulate cardiovascular system.This study was supported by grants from TUBITAK (110O878).