Maprotiline inhibits and gene expression in lipopolysaccharide-stimulated U937 macrophages and carrageenan-induced paw edema in rats.

Maprotiline, a tetracyclic antidepressant, is used for the management of mental disorders and various types of chronic pain. In our previous work, we found the inhibitory effect of maprotiline on inflammatory mediator's expression like tumor necrosis factor α (TNF-α and interleukin 1β (IL-1β. As part of that study, we sought to evaluate the effect of maprotiline on the expression of some inflammatory mediators such as cyclooxygenases 2 (COX2) and inducible nitric oxide synthase (iNOS). For this reason we used an in vitro model system of lipopolysaccharide (LPS)-stimulated human U937 macrophages and also an in vivo model of carrageenan-induced paw edema in rats. We measured the expression of these genes by quantitative RT-real time PCR. The expression of COX2 and iNOS significantly decreased by maprotiline in U937 macrophages and carrageenan-induced paw inflammation in rats. Our finding also confirmed that intraperitoneal (i.p.) injection of maprotiline inhibited carrageenan-induced paw edema. Moreover, maprotiline significantly decreased the migration of polymorphonuclear (PMN) leukocytes to the site of inflammation. The results of the present study provide further evidence for the anti-inflammatory effect of maprotiline. This effect appears to be mediated by down regulation of inflammatory genes. Further studies are needed to evaluate the complex cellular and molecular mechanisms of maprotiline.