Effect of Long-Term Centrally Injected Histamine and Its Receptors Antagonist on The Hypothalamic Cyclooxygenase and Lipoxygenase Enzymes in Rats

Abstract

The current study was designed to determine the effect of centrally chronic-administrated histamine and histaminergic receptors antagoniston the level of hypothalamic cyclooxygenase (COX) and lipoxygenase (LOX) enzymes.Studies were performed in male Sprague–Dawley rats. Histamine (100 nmol), histaminergic H1 receptor antagonist chlorpheniramine (100nmol), histaminergic H2 receptor antagonist ranitidine (100 nmol) or histaminergic H3/H4 receptor antagonist thioperamide (100 nmol)was injected intracerebroventricularly for 7 days. Central chronic histamine treatment caused increases in the levels of all three enzymes inthe hypothalamus. Central chronic treatments with all three histaminergic receptors antagonists reduced the hypothalamic COX-1 levels andraised the hypothalamic COX-2 and LOX levels.In conclusion, our findings show that the central histamine has a possible role to affect the central COX and LOX pathways. This could beinterpreted as that central histaminergic system might have a potential to activate central COX and LOX pathways to regulate central nervoussystem functions.