Priming of metabolic dysfunctions by prenatal immune activation in mice: relevance to schizophrenia

Schizophrenia is associated with increased risk for multiple metabolic abnormalities, including altered glucose homeostasis, type-2 diabetes, obesity, and cardiovascular disease. Some of the metabolic alterations can already exist in psychosis-prone subjects prior to the onset of chronic schizophrenic disease and pharmacotherapy, indicating that they may have a developmental origin. In the present study, we tested the hypothesis that metabolic alterations pertinent to schizophrenic disease can be primed by an environmental risk factor associated with the disorder, namely prenatal exposure to immune challenge. We used a well-established mouse model of prenatal immune challenge induced by maternal gestational treatment with poly(I:C) (="polyriboinosinic-polyribocytidilic acid"), an analog of double-stranded RNA that stimulates a cytokine-associated viral-like acute phase response. Metabolic effects were studied using high-resolution computed tomography and fully automated indirect calorimetry system, along with an oral glucose tolerance test and plasma cytokine and corticosterone measurements. We found that prenatal immune activation caused altered glycemic regulation and abnormal ingestive behavior in periadolescence and led to an adult onset of excess visceral and subcutaneous fat deposition. These effects were accompanied by age-dependent changes in peripheral secretion of proinflammatory (interleukin [IL]-6 and tumor necrosis factor [TNF]-α) and T cell-related (IL-2 and interferon [IFN]-γ) cytokines and by increased release of the stress hormone corticosterone in periadolescence. Our findings show that schizophrenia-relevant metabolic and physiological abnormalities can be primed by prenatal viral-like immune activation, but at the same time, our study emphasizes that this environmental insult is unlikely to precipitate the full spectrum of metabolic and immunological changes pertinent to chronic schizophrenic disease.