These findings indicate an elevated peripheral proinflammatory response, and provide further support for low grade inflammation in GAD. Further research may identify an 'inflammatory signature' for diagnosis and treatment response, and guide the search for novel pharmacological interventions.

No abstract

Although the pathogenesis of depression, an incapacitating psychiatric ailment, remains largely unknown, previous human and animal studies have suggested that both proinflammatory cytokines and altered oligodendrocytes play important roles in the condition. This study examined these two factors in the brains of rats following unpredictable chronic mild stress for 4 weeks, with the hypothesis that chronic stress may affect oligodendrocytes and elevate proinflammatory cytokines in the brain. After suffering unpredictable stressors for 4 weeks, the rats showed depression-like behaviors, including decreased locomotion in the open field, increased immobility time in the forced swim test, and decreased sucrose consumption and less sucrose preference when compared with controls. Immunohistochemical staining of brain sections showed higher immunoreactivity of proinflammatory cytokines in certain brain regions of stressed rats compared with controls; lower immunoreactivity of myelin basic protein and fewer mature oligodendrocytes were seen in the prefrontal cortex, but no demyelination was detected. These results are interpreted and discussed in the context of recent findings from human and animal studies.

Clinical studies have demonstrated that a single dose of ketamine produces complete remission within 24h in some depression patients. The ability of ketamine to produce fast-acting antidepressant-like effects in animal models depends on rapid synthesis of brain-derived neurotrophic factor (BDNF). Here we examined effects of a single dose dizocilpine, a non-competitive NMDA receptor antagonist, on the behavioral and neurobiological changes in rats treated with a single high dose reserpine, which is a monoamine re-uptake blocker and depletes monoamines in the brain with the outcome of depression-like symptoms in animals. A single high dose reserpine (4.0mg/kg) was given to rats intraperitoneally. Forty-eight hours later, the rats showed depressive symptoms as evidenced by decreased locomotor activity in the open field and increased immobility time in the forced swim test. Meanwhile, the treatment decreased BDNF levels and neurogenesis in the hippocampus. Pretreatment of a single dose dizocilpine (0.30mg/kg), however, prevented all the reserpine-induced changes, except for GluN1 subunit. These results are suggestive of the involvement of neurogenesis and BDNF in the rapid-acting antidepressant-like behavioral effects of the NMDA receptor antagonists in the reserpinized rats.