Involvement of dopamine D1 and D2 receptors in the rat nucleus accumbens in immunostimulation

Microglial synaptic pruning in the nucleus accumbens during adolescence sex-specifically influences splenic immune outcomes

Strong social support promotes a variety of positive health outcomes in humans and rodent models, while social isolation in rodents shortens lifespan, perceived social isolation (i.e. loneliness) can increase mortality by up to 50% in humans. How social relationships lead to these drastic health effects is unclear, but may involve modulation of the peripheral immune system. The reward circuitry of the brain and social behaviors undergo a critical period of development during adolescence. We published that microglia-mediated synaptic pruning occurs in the nucleus accumbens (NAc) reward region during adolescence to mediate social development in male and female rats. We hypothesized that if reward circuitry activity and social relationships directly impact the peripheral immune system, then natural developmental changes in the reward circuitry and social behaviors during adolescence should also directly impact the peripheral immune system. To test this, we inhibited microglial pruning in the NAc during adolescence, and then collected spleen tissue for mass spectrometry proteomic analysis and ELISA validation. We found that the global proteomic consequences of inhibiting microglial pruning in the NAc were similar between the sexes, but target-specific examination suggests that NAc pruning impacts Th1 cell-related immune markers in the spleen in males, but not females, and broad neurochemical systems in the spleen in females, but not males.

Effect of Antidepressants on Immunological Reactivity in ASC Mice with Genetically Determined Depression-Like State

The effect of chronic treatment with antidepressant drugs fluoxetine (20 mg/kg) and imipramine (25 mg/kg) on the number of antibody-producing cells and the main T cell subpopulations in ASC mice characterized by genetic predisposition to depression-like states was studied at the peak of the SE-induced immune response (5×10(8)). Fluoxetine produced an immunostimulatory effect manifested in an increase in the relative and absolute number of IgM antibody-producing cells in the spleen and index of immunoreactivity (CD4/CD8). Administration of fl uoxetine to parental mouse strains without depression (CBA and AKR) had no effect (CBA) or reduced the immune response. The CD4/CD8 ratio did not increase under these conditions. Imipramine was ineffective in the correction of immune reactions in a depression-like state.

Lipopolysaccharide-induced cytokine production in obsessive-compulsive disorder and generalized social anxiety disorder

The immune system is implicated in the pathophysiology of various psychiatric disorders. In anxiety disorders such as obsessive-compulsive disorder (OCD) and generalized social anxiety disorder (GSAD), immunological findings are equivocal and sparse. In this study, we investigated the lipopolysaccharide (LPS)- stimulated cytokine levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and interleukin-8 (IL-8) by peripheral blood leukocytes in 26 OCD patients, 26 GSAD patients, and 52 healthy controls. We found that leukocytes of OCD patients produced less IL-6 compared with matched controls, whereas no cytokine differences were found between GSAD patients and matched controls. When both patient groups were compared, a trend toward lower IL-6 levels in OCD patients was observed. This supports the idea of immunological involvement in the pathophysiology of OCD and suggests that GSAD and OCD might be different in immunological respect.