Pitolisant protects mice chronically treated with corticosterone from some behavioral but not metabolic changes in corticosterone-induced depression model

CircSYNDIG1 ameliorates stress-induced abnormal behaviors by suppressing miR-344-5p in mice

Circular RNA (circRNA) plays an important role in diverse stress-related neuropsychiatric disorders like depression, anxiety and cognitive disorders. Here, using a circRNA microarray, we found that circSYNDIG1, an unreported circRNA, was significantly downregulated in the hippocampus of chronic unpredictable mild stress (CUMS) mice and further validated this finding in corticosterone (CORT) and lipopolysaccharide (LPS) mice by qRT-PCR, and it was negatively correlated with depressive- and anxiety-like behaviors of these three stressed mice. Furthermore, the interaction of miR-344-5p and circSYNDIG1 was confirmed by in situ hybridization (FISH) assay in hippocampus and dual luciferase reporter assay in 293 T cells. And miR-344-5p mimics could simulate the dendritic spine density reduction, depressive- and anxiety-like behaviors and memory impairment induced by CUMS. Overexpression of circSYNDIG1 in hippocampus significantly ameliorated these abnormal changes induced by CUMS or miR-344-5p. It indicated that circSYNDIG1 functions as an miR-344-5p sponge to inhibit miR-344-5p impact, resulting in the increase of dendritic spine density and the subsequent amelioration of the abnormal behaviors. Therefore, the downregulation of circSYNDIG1 in hippocampus participates in CUMS-induced depressive and anxiety-like behavior of mice though miR-344-5p. These findings represent the first evidence for the involvement of circSYNDIG1 and its coupling mechanism in depression and anxiety, suggesting that circSYNDIG1 and miR-344-5p might be new targets for the treatment of stress-related disorder.

TRPA1 participation in behavioral impairment induced by chronic corticosterone administration

RATIONALE

Major depressive disorder (MDD) is one of the most diagnosed mental disorders. Despite this, its pathophysiology remains poorly understood. In this context, basic research aims to unravel the pathophysiological mechanisms of MDD as well as investigate new targets and substances with therapeutic potential. Transient receptor potential ankyrin 1 (TRPA1) is a transmembrane channel considered a sensor for inflammation and oxidative stress. Importantly, both inflammation and oxidative stress have been suggested as participants in the pathophysiology of MDD. However, the potential participation of TRPA1 in depressive disorder remains poorly investigated.

OBJECTIVE

To investigate the involvement of the TRPA1 channel in the behavioral changes induced by chronic corticosterone administration (CCA) in male mice.

METHODS

Swiss male mice were exposed to 21 days of CCA protocol and then treated with HC-030031 or A-967079, TRPA1 antagonists. Behavioral tests, analyzes of oxidative parameters and TRPA1 immunocontent were performed in the prefrontal cortex (PFC) and hippocampus (HIP).

RESULTS

CCA induced despair-like behavior in mice accompanied by an increase in the levels of hydrogen peroxide (H₂O₂), a TRPA1 agonist, which was reversed by TRPA1 antagonists and ketamine (positive control). In addition, CCA protocol reduced the immunocontent of this channel in the HIP and showed a tendency to increase the TRPA1 protein expression in the PFC.

CONCLUSION

Our work suggests that TRPA1 channel appears crucial to mediate the behavioral impairment induced by CCA in male Swiss mice.

Antipsychotic- and Anxiolytic-like Properties of a Multimodal Compound JJGW08 in Rodents

Schizophrenia is a chronic mental illness, which remains difficult to treat. A high resistance to the available therapies, their insufficient efficacy, and numerous side effects are the reasons why there is an urgent need to develop new antipsychotics. This study aimed to assess the antipsychotic-like effects of JJGW08, a novel arylpiperazine alkyl derivative of salicylamide, in rodents. First, considering the JJGW08 receptor profile, we investigated the compound's intrinsic activity towards dopamine D₂ and serotonin 5-HT_1A, 5-HT_2A, and 5-HT₇ receptors using functional assays. Next, we assessed the effect of JJGW08 on MK-801- and amphetamine-induced hyperlocomotion, its risk of inducing catalepsy and impairing motor coordination, as well as the anxiolytic-like effects in the four-plate and marble burying tests in mice. Finally, we investigated the antipsychotic-like properties of JJGW08 in rats using MK-801-induced hyperlocomotion and prepulse inhibition tests. We found that JJGW08 showed antagonistic properties at dopamine D₂ and serotonin 5-HT_1A, 5-HT_2A, and 5-HT₇ receptors. However, the effect on the 5-HT_2A and 5-HT₇ receptors was very weak. Moreover, the tested compound showed an antipsychotic-like effect in MK-801- and amphetamine-induced hyperlocomotion but not in a prepulse inhibition test in rats. Notably, JJGW08 demonstrated anxiolytic-like properties in both behavioral tests. Importantly, the compound did not induce catalepsy or motor coordination impairment in mice at antipsychotic-like doses. Our study suggests it is worth searching for new potential antipsychotics among arylpiperazine alkyl derivatives of salicylamide.

Revisiting Preclinical Observations of Several Histamine H3 Receptor Antagonists/Inverse Agonists in Cognitive Impairment, Anxiety, Depression, and Sleep-Wake Cycle Disorder

A relationship appears to exist between dysfunction of brain histamine (HA) and various neuropsychiatric brain disorders. The possible involvement of brain HA in neuropathology has gained attention recently, and its role in many (patho)physiological brain functions including memory, cognition, and sleep-wake cycle paved the way for further research on the etiology of several brain disorders. Histamine H3 receptor (H3R) evidenced in the brains of rodents and humans remains of special interest, given its unique position as a pre- and postsynaptic receptor, controlling the synthesis and release of HA as well as different other neurotransmitters in different brain regions, respectively. Despite several disappointing outcomes for several H3R antagonists/inverse agonists in clinical studies addressing their effectiveness in Alzheimer's disease (AD), Parkinson's disease (PD), and schizophrenia (SCH), numerous H3R antagonists/inverse agonists showed great potentials in modulating memory and cognition, mood, and sleep-wake cycle, thus suggesting its potential role in neurocognitive and neurodegenerative diseases such as AD, PD, SCH, narcolepsy, and major depression in preclinical rodent models. In this review, we present preclinical applications of selected H3R antagonists/inverse agonists and their pharmacological effects on cognitive impairment, anxiety, depression, and sleep-wake cycle disorders. Collectively, the current review highlights the behavioral impact of developments of H3R antagonists/inverse agonists, aiming to further encourage researchers in the preclinical drug development field to profile the potential therapeutic role of novel antagonists/inverse agonists targeting histamine H3Rs.