A multidimensional inflammatory response ensues after status epilepticus (SE), driven partly by cyclooxygenase-2-mediated activation of prostaglandin EP2 receptors. The inflammatory response is typified by astrocytosis, microgliosis, erosion of the blood-brain barrier (BBB), formation of inflammatory cytokines, and brain infiltration of blood-borne monocytes. Our previous studies have shown that inhibition of monocyte brain invasion or systemic administration of an EP2 receptor antagonist relieves multiple deleterious consequences of SE. Here we identify those effects of EP2 antagonism that are reproduced by conditional ablation of EP2 receptors in immune myeloid cells and show that systemic EP2 antagonism blocks monocyte brain entry in male mice. The induction of hippocampal IL-6 after pilocarpine SE was nearly abolished in EP2 conditional KO mice. Serum albumin levels in the cortex, a measure of BBB breakdown, were significantly higher after SE in EP2-sufficient mice but not in EP2 conditional KOs. EP2 deficiency in innate immune cells accelerated the recovery from sickness behaviors following SE. Surprisingly, neurodegeneration was not alleviated in myeloid conditional KOs. Systemic EP2 antagonism prevented monocyte brain infiltration and provided broader rescue of SE-induced effects than myeloid EP2 ablation, including neuroprotection and broader suppression of inflammatory mediators. Reporter expression indicated that the cellular target of CD11b-driven Cre was circulating myeloid cells but, unexpectedly, not microglia. These findings indicate that activation of EP2 receptors on immune myeloid cells drives substantial deficits in behavior and disrupts the BBB after SE. The benefits of systemic EP2 antagonism can be attributed, in part, to blocking brain recruitment of blood-borne monocytes.

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Mutations in the disrupted in schizophrenia-1 (DISC1) gene are associated with an increased risk of developing psychological disorders including schizophrenia, bipolar disorder, and depression. Assessing the impact of knocking out genes, like DISC1, in animal models provides valuable insights into the relationship between the gene and behavioral outcomes. Previous research has relied on mouse models to assess these impacts, however these may not yield as reliable or rich a behavioral analysis as can be obtained using rats. Thus, the goal of the present study was to characterize the behavioral effects of a biallelic functional deletion of the DISC1 gene in the Sprague Dawley rat. Female and male wild type and DISC1 knockout rats were assessed beginning just prior to weaning and during the post-weaning periadolescent period.The primary outcomes evaluated were activity, anxiety, responses to novel objects and conspecifics, and prepulse inhibition. These behaviors were selected as analogous indices of psychological dysfunction in humans. The DISC1 knockout had significant effects on behavior, although the kind and magnitude of deficits was different for females and males: in females, effects included hyperactivity, aversion to novelty, and a modest prepulse inhibition deficit; in males, effects in anxiety and neophobia were mild but their prepulse inhibition deficit was large. These data confirm that the DISC1 knockout rat model is an excellent way to reproduce and study symptoms of psychological disorders and provides compelling evidence for differential consequences of its dysfunction for females and males in the progression and emergence of specific behavioral deficits.

The human gastrointestinal tract is home to trillions of microorganisms—collectively referred to as the gut microbiome—that maintain a symbiotic relationship with their host. This diverse community of microbes grows and changes as we do, with developmental, lifestyle, and environmental factors all shaping microbiome community structure. Increasing evidence suggests this relationship is bidirectional, with the microbiome also influencing host physiological processes. For example, changes in the gut microbiome have been shown to alter neurodevelopment and have lifelong effects on the brain and behavior. Age-related changes in gut microbiome composition have also been linked to inflammatory changes in the brain, perhaps increasing susceptibility to neurological disease. Indeed, associations between gut dysbiosis and many age-related neurological diseases—including Parkinson's disease, Alzheimer's disease, multiple sclerosis, and amyotrophic lateral sclerosis—have been reported. Further, microbiome manipulation in animal models of disease highlights a potential role for the gut microbiome in disease development and progression. Although much remains unknown, these associations open up an exciting new world of therapeutic targets, potentially allowing for improved quality of life for a wide range of patient populations.

Background: Regulatory interactions between the gut and the brain are essential for energy homeostasis across systems. Current evidence indicates high-fat, high-carbohydrate diets (HFHC) impact Alzheimer's disease (AD) pathophysiology, however, the mechanisms underlying this association are poorly understood. We hypothesize that (1) Tumor Necrosis Factor (TNF) mediates metabolic inflammation in an obesogenic environment with impacts across the gut-brain axis and (2) that HFHC interacts with an AD-relevant genetic background to promote metabolic and immune dysregulation that accelerates pathological and behavioral dysfunction in an animal model of AD. Method:To investigate the effects of chronic systemic inflammation on AD-associated pathology, 2-month old female 5xFAD mice were fed HFHC or a control diets (CD) for 8 weeks. One month following dietary intervention, the brain-permeant soluble TNF inhibitor XPro1595 or a brain-impermeant pan (sol and membrane-bound) TNF inhibitor Etanercept (Enbrel, Amgen-Wyeth) or vehicle (saline) were dosed twice weekly for 4 weeks. Behavioral test were performed to assess cognitive parameters.Plasma, brain and gut were collected for evaluation of insulin impairment, metabolic and immune parameters. Cortical tissues were subjected to RNAseq analysis to determine gene pathways modified by interactions between diet, genotype, and TNF inhibition.Result: HFHC promoted metabolic syndrome features associated with increases in adiposity, body weight, and plasma glucose, cholesterol, leptin, and insulin. TNF inhibition did not rescue diet-induced insulin increases, however XPro specifically reduced plasma glucose, while Enbrel increased HOMA-IR in HFHC-fed mice. HFHC diet increased circulating IL-6, CXCL1, CXCL2 and CCL2 and TNF neutralization with either drug decreased IL-6 in HFHC-fed groups. In the colon, HFHC diet decreased CCL3 and TNF blockade increased colonic IL-15 in HFHC-fed mice. Ongoing behavioral assessment, cortical transcriptional analysis, and hippocampal protein profiles of