Effect of long-term centrally ınjected histamine and ıts 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 antagonist on 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 (100 nmol), 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 in the hypothalamus. Central chronic treatments with all three histaminergic receptors antagonists reduced the hypothalamic COX-1 levels and raised 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 be interpreted as that central histaminergic system might have a potential to activate central COX and LOX pathways to regulate central nervous system functions.