Antidepressant‐like effect of anacardic acid in mice via the L‐arginine–nitric oxide–serotonergic system

Anacardic acid improves neurological deficits in traumatic brain injury by anti-ferroptosis and anti-inflammation

BACKGROUND

Traumatic brain injury (TBI) is an important cause of disability and death. TBI leads to multiple forms of nerve cell death including ferroptosis due to iron-dependent lipid peroxidation. Anacardic acid (AA) is a natural component extracted from cashew nut shells, which has been reported to have neuroprotective effects in traumatic brain injury. We investigated whether AA has an anti-ferroptosis effect in TBI.

METHODS

We used the Feeney free-fall impact method to construct a TBI model to investigate the effect of AA on ferroptosis caused by TBI, in which Ferrostatin-1 (Fer-1), a ferroptosis inhibitor, served as a positive control group. We first identified the therapeutic effect of AA on TBI through modified neurological severity score (mNSS) and determined the appropriate concentration. Secondly, we investigated the effect of AA on the expression level of the key protein of ferroptosis by Western blotting and immunohistochemistry. Then the effect of AA on nerve tissue injury and nerve function improvement was verified. Finally, enzym-linked immunosorbent assay (ELISA) was used to verify that AA could reduce inflammation after TBI.

RESULTS

We found the intensely inhibitory effect of AA on ferroptosis, which is in parallel with the results obtained after Fer-1 treatment. In addition, AA and Fer-1 mitigated TBI-mediated tissue defects, destruction of the blood-brain barrier, and neurodegeneration. Novel object recognition (NOR), mNSS and water maze test showed that AA could significantly reduce the impairment of neural function and behavioral cognitive ability caused by TBI. Finally, we also demonstrated that AA has not only an anti-ferroptosis effect, but also an anti-inflammation effect.

CONCLUSIONS

AA can reduce the neurological impairment and behavioral cognitive impairment caused by TBI through the dual effect of anti-ferroptosis and anti-inflammation.

Dissecting the Relationship Between Neuropsychiatric and Neurodegenerative Disorders

Neurodegenerative diseases (NDDs) and neuropsychiatric disorders (NPDs) are two common causes of death in elderly people, which includes progressive neuronal cell death and behavioral changes. NDDs include Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, multiple sclerosis, and motor neuron disease, characterized by cognitive defects and memory impairment, whereas NPDs include depression, seizures, migraine headaches, eating disorders, addictions, palsies, major depressive disorders, anxiety, and schizophrenia, characterized by behavioral changes. Mounting evidence demonstrated that NDDs and NPDs share an overlapping mechanism, which includes post-translational modifications, the microbiota-gut-brain axis, and signaling events. Mounting evidence demonstrated that various drug molecules, namely, natural compounds, repurposed drugs, multitarget directed ligands, and RNAs, have been potentially implemented as therapeutic agents against NDDs and NPDs. Herein, we highlighted the overlapping mechanism, the role of anxiety/stress-releasing factors, cytosol-to-nucleus signaling, and the microbiota-gut-brain axis in the pathophysiology of NDDs and NPDs. We summarize the therapeutic application of natural compounds, repurposed drugs, and multitarget-directed ligands as therapeutic agents. Lastly, we briefly described the application of RNA interferences as therapeutic agents in the pathogenesis of NDDs and NPDs. Neurodegenerative diseases and neuropsychiatric diseases both share a common signaling molecule and molecular phenomenon, namely, pro-inflammatory cytokines, γCaMKII and MAPK/ERK, chemokine receptors, BBB permeability, and the gut-microbiota-brain axis. Studies have demonstrated that any alterations in the signaling mentioned above molecules and molecular phenomena lead to the pathophysiology of neurodegenerative diseases, namely, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis, and neuropsychiatric disorders, such as bipolar disorder, schizophrenia, depression, anxiety, autism spectrum disorder, and post-traumatic stress disorder.

In Silico Study Examining New Phenylpropanoids Targets with Antidepressant Activity

BACKGROUND

Natural products, such as phenylpropanoids, which are found in essential oils derived from aromatic plants, have been explored during non-clinical psychopharmacology studies, to discover new molecules with relevant pharmacological activities in the central nervous system, especially antidepressant and anxiolytic activities. Major depressive disorder is a highly debilitating psychiatric disorder and is considered to be a disabling public health problem, worldwide, as a primary factor associated with suicide. Current clinically administered antidepressants have late-onset therapeutic actions, are associated with several side effects, and clinical studies have reported that some patients do not respond well to treatment or reach complete remission.

OBJECTIVE

To review important new targets for antidepressant activity and to select phenylpropanoids with antidepressant activity, using Molegro Virtual Docker and Ossis Data Warris, and to verify substances with more promising antidepressant activity.

RESULTS AND CONCLUSION

An in silico molecular modeling study, based on homology, was conducted to determine the three-dimensional structure of the 5-hydroxytryptamine 2A receptor (5- HT2AR), then molecular docking studies were performed and the predisposition for cytotoxicity risk among identified molecules was examined. A model for 5-HT2AR homology, with satisfactory results, was obtained indicating the good stereochemical quality of the model. The phenylpropanoid 4-allyl-2,6-dimethoxyphenol showed the lowest binding energy for 5-HT2AR, with results relevant to the L-arginine/nitric oxide (NO)/cGMP pathway, and showed no toxicity within the parameters of mutagenicity, carcinogenicity, reproductive system toxicity, and skin-tissue irritability, when evaluated in silico; therefore, this molecule can be considered promising for the investigation of antidepressant activity.

Saikosaponin-d attenuated lipopolysaccharide-induced depressive-like behaviors via inhibiting microglia activation and neuroinflammation

Saikosaponin-d (SSd), a triterpenoid saponins compound extracted from Radix Bupleuri, has been demonstrated to effectively alleviate chronic mild stress-induced depressive behaviors in rats, but the underlying molecular mechanisms are still uncertain. Increasing evidence indicated that microglia activation and inflammatory responses were involved in the pathogenesis of depression. Thus, we desired to induce inflammation-related depressive-like behaviors in mice by injecting lipopolysaccharide (LPS) to investigate whether the antidepressant effect of SSd is related to inhibiting inflammation. The results of behavioral tests showed that SSd administration ameliorated LPS-induced depressive-like behaviors, as shown by increased sucrose consumption in the sucrose preference test and decreased immobility time in the tail suspension test and forced swimming test. Furthermore, immunostaining results showed that SSd pretreatment inhibited LPS-induced microglia activation in the hippocampus of mice and primary microglia cells. Enzyme-linked immunosorbent assay (ELISA) results showed that SSd pretreatment suppressed LPS-induced overexpression of inflammatory factors such as interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α both in vivo and in vitro. Immunostaining and western blot analysis results demonstrated that SSd pretreatment also inhibited LPS-induced HMGB1 translocation from nuclear to extracellular and decreased the protein levels of TLR4, p-IκB-α, NF-κBp65. These results suggested that SSd effectively improved LPS-induced inflammation-related depressive-like behaviors by inhibiting LPS-induced microglia activation and neuroinflammation, and the possible mechanism might associate with the regulation of the HMGB1/TLR4/NF-κB signaling pathway.