Quetiapine Ameliorates MIA-Induced Impairment of Sensorimotor Gating: Focus on Neuron-Microglia Communication and the Inflammatory Response in the Frontal Cortex of Adult Offspring of Wistar Rats

Prenatal Immune Challenge Differentiates the Effect of Aripiprazole and Risperidone on CD200-CD200R and CX3CL1-CX3CR1 Dyads and Microglial Polarization: A Study in Organotypic Cortical Cultures

Microglia are the primary innate immune cells of the central nervous system and extensively contribute to brain homeostasis. Dysfunctional or excessive activity of microglia may be associated with several neuropsychiatric disorders, including schizophrenia. Therefore, we examined whether aripiprazole and risperidone could influence the expression of the Cd200-Cd200r and Cx3cl1-Cx3cr1 axes, which are crucial for the regulation of microglial activity and interactions of these cells with neurons. Additionally, we evaluated the impact of these drugs on microglial pro- and anti-inflammatory markers (Cd40, Il-1β, Il-6, Cebpb, Cd206, Arg1, Il-10 and Tgf-β) and cytokine release (IL-6, IL-10). The research was executed in organotypic cortical cultures (OCCs) prepared from the offspring of control rats (control OCCs) or those exposed to maternal immune activation (MIA OCCs), which allows for the exploration of schizophrenia-like disturbances in animals. All experiments were performed under basal conditions and after additional stimulation with lipopolysaccharide (LPS), following the "two-hit" hypothesis of schizophrenia. We found that MIA diminished the mRNA level of Cd200r and affected the OCCs' response to additional LPS exposure in terms of this parameter. LPS downregulated the Cx3cr1 expression and profoundly changed the mRNA levels of pro- and anti-inflammatory microglial markers in both types of OCCs. Risperidone increased Cd200 expression in MIA OCCs, while aripiprazole treatment elevated the gene levels of the Cx3cl1-Cx3cr1 dyad in control OCCs. The antipsychotics limited the LPS-generated increase in the expression of proinflammatory factors (Il-1β and Il-6) and enhanced the mRNA levels of anti-inflammatory components (Cd206 and Tgf-β) of microglial polarization, mostly in the absence of the MIA procedure. Finally, we observed a more pronounced modulating impact of aripiprazole on the expression of pro- and anti-inflammatory cytokines when compared to risperidone in MIA OCCs. In conclusion, our data suggest that MIA might influence microglial activation and crosstalk of microglial cells with neurons, whereas aripiprazole and risperidone could beneficially affect these changes in OCCs.

Quetiapine improves sensorimotor gating deficit in a sleep deprivation-induced rat model

Background

Sleep deprivation (SD) impairs pre-stimulus inhibition, but the effect of quetiapine (QET) remains largely unknown.

Objective

This study aimed to investigate the behavioral and cognitive effects of QET in both naïve and sleep-deprived rats.

Materials and methods

Seven groups (n = 49) of male Wistar Albino rats were used in this study. SD was performed using the modified multiple platform technique in a water tank for 72 h. Our study consists of two experiments investigating the effect of QET on pre-pulse inhibition (PPI) of the acoustic startle reflex. The first experiment tested the effect of short- and long-term administration of QET on PPI response in non-sleeping (NSD) rats. The second experiment used 72 h REM sleep deprivation as a model for SD-induced impairment of the PPI response. Here, we tested the effect of QET on the % PPI of SD rats by short- and long-term intraperitoneal injection at the last 90 min of sleep SD and immediately subsequently tested for PPI.

Results

72 h SD impaired PPI, reduced startle amplitude, and attenuated the PPI% at + 4 dB, + 8 dB, and + 16 dB prepulse intensities. 10 mg/kg short and long-term QET administration completely improved sensorimotor gating deficit, increased startle amplitude, and restored the impaired PPI% at + 4 dB, + 8 dB, and + 16 dB after 72 h SD in rats.

Conclusion

Our results showed short- and long-term administration of QET improved sensorimotor gating deficit in 72 h SD. Further research is required for the etiology of insomnia and the dose-related behavioral effects of QET.

Neurodevelopmental and Neuropsychiatric Disorders

This chapter will focus on microglial involvement in neurodevelopmental and neuropsychiatric disorders, particularly autism spectrum disorder (ASD), schizophrenia and major depressive disorder (MDD). We will describe the neuroimmune risk factors that contribute to the etiopathology of these disorders across the lifespan, including both in early life and adulthood. Microglia, being the resident immune cells of the central nervous system, could play a key role in triggering and determining the outcome of these disorders. This chapter will review preclinical and clinical findings where microglial morphology and function were examined in the contexts of ASD, schizophrenia and MDD. Clinical evidence points out to altered microglial morphology and reactivity, as well as increased expression of pro-inflammatory cytokines, supporting the idea that microglial abnormalities are involved in these disorders. Indeed, animal models for these disorders found altered microglial morphology and homeostatic functions which resulted in behaviours related to these disorders. Additionally, as microglia have emerged as promising therapeutic targets, we will also address in this chapter therapies involving microglial mechanisms for the treatment of neurodevelopmental and neuropsychiatric disorders.

The Janus face of antipsychotics in glial cells: Focus on glioprotection

Antipsychotics are commonly prescribed to treat several neuropsychiatric disorders, including schizophrenia, mania in bipolar disorder, autism spectrum disorder, delirium, and organic or secondary psychosis, for example, in dementias such as Alzheimer's disease. There is evidence that typical antipsychotics such as haloperidol are more effective in reducing positive symptoms than negative symptoms and/or cognitive deficits. In contrast, atypical antipsychotic agents have gained popularity over typical antipsychotics, due to fewer extrapyramidal side effects and their theoretical efficacy in controlling both positive and negative symptoms. Although these therapies focus on neuron-based therapeutic schemes, glial cells have been recognized as important regulators of the pathophysiology of neuropsychiatric disorders, as well as targets to improve the efficacy of these drugs. Glial cells (astrocytes, oligodendrocytes, and microglia) are critical for the central nervous system in both physiological and pathological conditions. Astrocytes are the most abundant glial cells and play important roles in brain homeostasis, regulating neurotransmitter systems and gliotransmission, since they express a wide variety of functional receptors for different neurotransmitters. In addition, converging lines of evidence indicate that psychiatric disorders are commonly associated with the triad neuroinflammation, oxidative stress, and excitotoxicity, and that glial cells may contribute to the gliotoxicity process. Conversely, glioprotective molecules attenuate glial damage by generating specific responses that can protect glial cells themselves and/or neurons, resulting in improved central nervous system (CNS) functioning. In this regard, resveratrol is well-recognized as a glioprotective molecule, including in clinical studies of schizophrenia and autism. This review will provide a summary of the dual role of antipsychotics on neurochemical parameters associated with glial functions and will highlight the potential activity of glioprotective molecules to improve the action of antipsychotics.

Insights into the Potential Impact of Quetiapine on the Microglial Trajectory and Inflammatory Response in Organotypic Cortical Cultures Derived from Rat Offspring

Atypical antipsychotics currently constitute the first-line medication for schizophrenia, with quetiapine being one of the most commonly prescribed representatives of the group. Along with its specific affinity for multiple receptors, this compound exerts other biological characteristics, among which anti-inflammatory effects are strongly suggested. Simultaneously, published data indicated that inflammation and microglial activation could be diminished by stimulation of the CD200 receptor (CD200R), which takes place by binding to its ligand (CD200) or soluble CD200 fusion protein (CD200Fc). Therefore, in the present study, we sought to evaluate whether quetiapine could affect certain aspects of microglial activity, including the CD200-CD200R and CX3CL1-CX3CR1 axes, which are involved in the regulation of neuron-microglia interactions, as well as the expression of selected markers of the pro- and anti-inflammatory profile of microglia (Cd40, Il-1β, Il-6, Cebpb, Cd206, Arg1, Il-10 and Tgf-β). Concurrently, we examined the impact of quetiapine and CD200Fc on the IL-6 and IL-10 protein levels. The abovementioned aspects were investigated in organotypic cortical cultures (OCCs) prepared from the offspring of control rats (control OCCs) or those subjected to maternal immune activation (MIA OCCs), which is a widely implemented approach to explore schizophrenia-like disturbances in animals. The experiments were performed under basal conditions and after additional exposure to the bacterial endotoxin lipopolysaccharide (LPS), according to the "two-hit" hypothesis of schizophrenia. The results of our research revealed differences between control and MIA OCCs under basal conditions and in response to treatment with LPS in terms of lactate dehydrogenase and nitric oxide release as well as Cd200r, Il-1β, Il-6 and Cd206 expression. The additional stimulation with the bacterial endotoxin resulted in a notable change in the mRNA levels of pro- and anti-inflammatory microglial markers in both types of OCCs. Quetiapine diminished the influence of LPS on Il-1β, Il-6, Cebpb and Arg1 expression in control OCCs as well as on IL-6 and IL-10 levels in MIA OCCs. Moreover, CD200Fc reduced the impact of the bacterial endotoxin on IL-6 production in MIA OCCs. Thus, our results demonstrated that quetiapine, as well as the stimulation of CD200R by CD200Fc, beneficially affected LPS-induced neuroimmunological changes, including microglia-related activation.