Pharmacological and proteomic analyses of neonatal polyI:C-treated adult mice

Effects of different types of induced neonatal inflammation on development and behavior of C57BL/6 and BTBR mice

Neuroinflammation in the early postnatal period can disturb trajectories of the completion of normal brain development and can lead to mental illnesses, such as depression, anxiety disorders, and personality disorders later in life. In our study, we focused on evaluating short- and long-term effects of neonatal inflammation induced by lipopolysaccharide, poly(I:C), or their combination in female and male C57BL/6 and BTBR mice. We chose the BTBR strain as potentially more susceptible to neonatal inflammation because these mice have behavioral, neuroanatomical, and physiological features of autism spectrum disorders, an abnormal immune response, and several structural aberrations in the brain. Our results indicated that BTBR mice are more sensitive to the influence of the neonatal immune activation (NIA) on the formation of neonatal reflexes than C57BL/6 mice are. In these experiments, the injection of lipopolysaccharide had an effect on the formation of the cliff aversion reflex in female BTBR mice. Nonetheless, NIA had no delayed effects on either social behavior or anxiety-like behavior in juvenile and adolescent BTBR and C57BL/6 mice. Altogether, our data show that NIA has mimetic-, age-, and strain-dependent effects on the development of neonatal reflexes and on exploratory activity in BTBR and C57BL/6 mice.

Early-life stress contributes to depression-like behaviors in a two-hit mouse model

BACKGROUND

Depression is a common psychological disorder with pathogenesis involving genetic and environmental interactions. Early life stress can adversely affect physical and emotional development and dramatically increase the risk for the development of depression and anxiety disorders.

METHODS

To examine potential early life stress driving risk for anxiety and depression, we used a two-hit developmental stress model，injecting poly(I: C) into neonatal mice on P2-P6 followed by peripubertal unpredictable stress in adolescence.

RESULTS

Our study shows that early-life and adolescent stress leads to anxiety and depression-related behavioral phenotypes in male mice. Early-life stress exacerbated depression-like behavior in mice following peripubertal unpredictable stress. We confirmed that early life stress might be involved in the decreased neuronal activity in the medial prefrontal cortex (mPFC) and might be involved in shaping behavioral phenotypes of animals. We found that increased microglia and neuroinflammation in the mPFC of two-hit mice and early life stress further boost microglia activation and inflammatory factors in the mPFC region of mice following adolescent stress.

LIMITATIONS

The specific neural circuits and mechanisms by which microglia regulate depression-like behaviors require further investigation.

CONCLUSIONS

Our findings provide a novel insight into developmental risk factors and biological mechanisms in depression and anxiety disorders.

Group I mGluRs positive allosteric modulators improved schizophrenia-related behavioral and molecular deficits in the Poly I:C rat model

RATIONALE

Maternal polyinosinic-polycytidylic acid (Poly I:C) exposure leads to an increase in various proinflammatory cytokines and causes schizophrenia-like symptoms in offspring. In recent years, group I metabotropic glutamate receptors (mGluRs) have emerged as a potential target in the pathophysiology of schizophrenia.

OBJECTIVES

The aim of our study was to investigate the behavioral and molecular changes by using the mGlu1 receptor positive allosteric modulator (PAM) agent RO 67-7476, and the negative allosteric modulator (NAM) agent JNJ 16259685 and the mGlu5 receptor PAM agent VU-29, and NAM agent fenobam in the Poly I:C-induced schizophrenia model in rats.

METHODS

Female Wistar albino rats were treated with Poly I:C on day 14 of gestation after mating. On the postnatal day (PND) 35, 56 and 84, behavioral tests were performed in the male offspring. On the PND84, brain tissue was collected and the level of proinflammatory cytokines was determined by ELISA method.

RESULTS

Poly I:C caused impairments in all behavioral tests and increased the levels of proinflammatory cytokines. While PAM agents caused significant improvements in prepulse inhibition (PPI), novel object recognition (NOR), spontaneous alternation and reference memory tests, they brought the levels of proinflammatory cytokines closer to the control group. NAM agents were ineffective on behavioral tests. It was observed that PAM agents significantly improved Poly I:C-induced disruption in behavioral and molecular analyses.

CONCLUSIONS

These results suggest that PAM agents, particularly the mGlu5 receptor VU-29, are also promising and could be a potential target in schizophrenia.

Antipsychotic-like effects of fasudil, a Rho-kinase inhibitor, in a pharmacologic animal model of schizophrenia

Current antipsychotics used to treat schizophrenia have associated problems, including serious side effects and treatment resistance. We recently identified a significant association of schizophrenia with exonic copy number variations in the Rho GTPase activating protein 10 (ARHGAP10) gene using genome-wide analysis. ARHGAP10 encodes a RhoGAP superfamily member that is involved in small GTPase signaling. In mice, Arhgap10 gene variations result in RhoA/Rho-kinase pathway activation. We evaluated the pharmacokinetics of fasudil and hydroxyfasudil using liquid chromatography-tandem mass spectrometry in mice. The antipsychotic effects of fasudil on hyperlocomotion, social interaction deficits, prepulse inhibition deficits, and novel object recognition deficits were also investigated in a MK-801-treated pharmacological mouse schizophrenia model. Fasudil and its major metabolite, hydroxyfasudil, were detected in the brain at concentrations above their respective K_i values for Rho-kinase after intraperitoneal injection of 10 mg kg^-1 fasudil. Fasudil improved the hyperlocomotion, social interaction deficits, prepulse inhibition deficits, and novel object recognition deficits in MK-801-treated mice in a dose-dependent manner. Following oral administration of fasudil, brain hydroxyfasudil was detected at concentration above the K_i value for Rho-kinase whilst fasudil was undetectable. MK-801-induced hyperlocomotion was also improved by oral fasudil administration. These results suggest that fasudil has antipsychotic-like effects on the MK-801-treated pharmacological mouse schizophrenia model. There are two isoforms in Rho-kinase, and further investigation is needed to clarify the isoforms involved in the antipsychotic-like effects of fasudil in the MK-801-treated mouse schizophrenia model.

Linking Inflammation, Aberrant Glutamate-Dopamine Interaction, and Post-synaptic Changes: Translational Relevance for Schizophrenia and Antipsychotic Treatment: a Systematic Review

Evidence from clinical, preclinical, and post-mortem studies supports the inflammatory/immune hypothesis of schizophrenia pathogenesis. Less evident is the link between the inflammatory background and two well-recognized functional and structural findings of schizophrenia pathophysiology: the dopamine-glutamate aberrant interaction and the alteration of dendritic spines architecture, both believed to be the “quantal” elements of cortical-subcortical dysfunctional network. In this systematic review, we tried to capture the major findings linking inflammation, aberrant glutamate-dopamine interaction, and post-synaptic changes under a direct and inverse translational perspective, a paramount picture that at present is lacking. The inflammatory effects on dopaminergic function appear to be bidirectional: the inflammation influences dopamine release, and dopamine acts as a regulator of discrete inflammatory processes involved in schizophrenia such as dysregulated interleukin and kynurenine pathways. Furthermore, the link between inflammation and glutamate is strongly supported by clinical studies aimed at exploring overactive microglia in schizophrenia patients and maternal immune activation models, indicating impaired glutamate regulation and reduced N-methyl-D-aspartate receptor (NMDAR) function. In addition, an inflammatory/immune-induced alteration of post-synaptic density scaffold proteins, crucial for downstream NMDAR signaling and synaptic efficacy, has been demonstrated. According to these findings, a significant increase in plasma inflammatory markers has been found in schizophrenia patients compared to healthy controls, associated with reduced cortical integrity and functional connectivity, relevant to the cognitive deficit of schizophrenia. Finally, the link between altered inflammatory/immune responses raises relevant questions regarding potential new therapeutic strategies specifically for those forms of schizophrenia that are resistant to canonical antipsychotics or unresponsive to clozapine.

Application of animal experimental models in the research of schizophrenia

Schizophrenia is a relatively common but serious mental illness that results in a heavy burden to patients, their families, and society. The disease can be triggered by multiple factors, while the specific pathogenesis remains unclear. The development of effective therapeutic drugs for schizophrenia relies on a comprehensive understanding of the basic biology and pathophysiology of the disease. Therefore, effective animal experimental models play a vital role in the study of schizophrenia. Based on different molecular mechanisms and modeling methods, the currently used experimental animal experimental models of schizophrenia can be divided into four categories that can better simulate the clinical symptoms and the interplay between susceptible genes and the environment: neurodevelopmental, drug-induced, genetic-engineering, and genetic-environmental interaction of animal experimental models. Each of these categories contains multiple subtypes, which has its own advantages and disadvantages and therefore requires careful selection in a research application. The emergence and utilization of these models are promising in the prediction of the risk of schizophrenia at the molecular level, which will shed light on effective and targeted treatment at the genetic level.