Short Communication Effects of Histamine on Phosphoinositide Metabolism in Chick Cerebral Cortex

Effects of histamine (HA) and agonists of HA receptors on phosphoinositide metabolism in chick cerebral cortex have been studied using two approaches – measurement of inositol 1,4,5-trisphosphate (IP ) level by a specific and sensitive IP receptor radioassay, and analysis of [ H]inositol phosphates accumulation in cortical slices prelabeled with myo-[ H]inositol. HA concentration-dependently elevated IP levels in slices of chick cerebral cortex. The effect of HA was mimicked by 2-methylHA, a selective agonist of H -HA receptors, and blocked by mepyramine, an H receptor antagonist. 4-MethylHA and R -methylHA, selective agonists of H and H -HA receptors, respectively, did not affect IP level in the chick cerebrum. In cerebral cortical slices prelabeled with myo-[ H]inositol, 2-methylHA significantly stimulated [ H]inositol phosphates accumulation, whereas HA only slightly and non-significantly increased phosphoinositide metabolism. It is suggested that phospholipase C-coupled H -HA receptors are present in the chick cerebral cortex, yet their number seems to be a small one.