97 Other clinical studies have suggested that the COX2 inhibitor celecoxib has positive effects on cognitive function in depressed

patients.97 It should be noted that celecoxib has also been shown to have beneficial effects as an “add-on” component to clozapine in the treatment of schizophrenia in patients who are only partially responding to the antipsychotic medication.98,99 There are several mechanisms that are postulated to be involved in the etiology of depression. It is commonly Inhibitors,research,lifescience,medical assumed that a selleck chemicals llc decrease in both the noradrenergic and serotonergic functions are causally related to the changes in the mood, motivation, and cognitive changes associated with the disorder, There is now experimental evidence to show that the inhibition of COX2 is associated with a rise in the synthesis of serotonin Inhibitors,research,lifescience,medical in the cortex of the rat brain.100 In addition, PGE2 has been shown to reduce the release

of noradrenaline from central noradrenergic neurons, an effect that would be blocked by the COX2 inhibitors. Thus Inhibitors,research,lifescience,medical inhibition of COX2 activity in the brain contributes not only to the reduction in inflammatory changes but also to an enhancement of biogenic amine function. PGE2 is probably one of the most potent inflammatory mediators in terms of the initiation Inhibitors,research,lifescience,medical and propagation of inflammation within the brain.101 Both clinical90,102 and experimental

studies have shown that there is an increase in the tissue concentrations of PGE2 in depression and in an animal model of depression.89 In the brain, the microglia act as macrophages. On activation, they release proinflammatory cytokines, PGE2, and neurotoxic metabolites of the kynurenine pathway.103 Recent experimental evidence has shown that lipopoly saccharide (LPS), an activator of macrophage activity and a cause Inhibitors,research,lifescience,medical of brain inflammation, induces mitochondrial PGE2 synthase and COX2 activity in activated microglia, thereby increasing the synthesis of PGE2 at sites of inflammation in the brain.104 This provides a possible mechanism to Phosphatidylinositol diacylglycerol-lyase explain the inflammatory changes in patients with depression or dementia; changes that contribute to neurodegeneration. Nitric oxide (NO) can also act as an inflammatory mediator that contributes to neurodegeneration,105 and is raised in the plasma of depressed patients.106 NO is produced by both the constitutive and inducible forms of NO synthase (NOS) that are associated with neurons and microglia.107-109 Recent evidence suggests that proinflammatory cytokines activate inducible NOS, thereby increasing NO; apoptosis results from the nitrosylation of deoxyribonucleic acid (DNA).