Effects of SSRIs on peripheral inflammatory cytokines in patients with Generalized Anxiety Disorder.

BACKGROUND: Extensive research into psychoneuroimmunology has led to substantial advances in our understanding of the reciprocal interactions between the central nervous system and the immune system in neuropsychiatric disorders. To date, inflammation has been implicated in the pathogenesis of depression and anxiety. The immunomodulating effects of antidepressants on depression have been reported, however, there is no evidence of the similar effects of antidepressants on anxiety. The aim of the study was to investigate the effects of selective serotonin reuptake inhibitors (SSRIs) on peripheral inflammatory cytokines in patients with first episode generalized anxiety disorder (GAD). METHODS: A prospective cohort design was employed: 42 patients with first episode GAD were treated with either escitalopram or sertraline for 12 weeks. Anxiety was measured by the Generalized Anxiety Disorder Scale and the State Trait Anxiety Inventory, serum pro-inflammatory cytokine levels were measured by the enzyme-linked immunosorbent assay (ELISA), and CRP determined by an immunoturbidimetric method before and after SSRIs treatment RESULTS: Baseline levels of anxiety and pro-inflammatory cytokines including IL-1α, IL-6, IL-8, IL-12, IFN-γ, and CRP were significantly reduced after treatment of SSRIs (p < 0.05 in all cases). In addition, the change of anxiety measures co-vary with the change of peripheral cytokine levels (p < 0.05 in all cases). The regression model revealed that log transformed baseline levels of CRP and IL-6 predicted treatment response (p < 0.05 in both cases). CONCLUSIONS: This study is the first to investigate the effects of SSRIs on pro-inflammatory cytokines in patients with first episode GAD. The findings indicate moderate acute anti-inflammatory effects of SSRIs in GAD, and suggest that these anti-inflammatory effects may underlie anxiolytic effects of SSRIs. The study also indicates that serum levels of CRP and IL-6 may predict treatment response. However, data from randomized controlled trials is warranted to confirm these findings.

Peripheral proinflammatory cytokines in Chinese patients with generalised anxiety disorder.

BACKGROUND: Inflammatory responses and inflammatory cytokines have been implicated in the pathogenesis of affective disorders, particularly major depression. Given the limited evidence relating to the potential role of proinflammatory cytokines in generalised anxiety disorder (GAD), we aimed to examine peripheral proinflammatory cytokines in Chinese patients with GAD. METHODS: A case-controlled cross-sectional study design, with recruitment of 48 patients with first episode GAD and 48 matched healthy controls. All participants completed measures of anxiety using well-established questionnaires, and serum levels of pro-inflammatory cytokines were measured using multiplex technology. RESULTS: Serum levels of CRP, IL-1α, IL-2, IL-6, IL-8, IL-12, IFN-γ, and GM-CSF were significantly higher in the GAD group in comparison to the control group (p < 0.05). Pearson correlation revealed significant positive correlations between anxiety measures and serum levels of CRP, IL-1α, IL-6, IL-8, IFN-γ, and GM-CSF (p < 0.05). LIMITATIONS: The cross-sectional study design does not permit definite conclusions on causal directions between inflammation and GAD. The study was limited to a panel of 8 cytokines and does not exclude the possibility of other important cytokines being involved. CONCLUSIONS: 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.

The influence of dizocilpine on the reserpine-induced behavioral and neurobiological changes in rats.

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.

Changes in proinflammatory cytokines and white matter in chronically stressed rats.

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.