Effects of psychoactive drugs on cellular bioenergetic pathways

Neuroprotective effects of selenium against lithium-induced cerebellar toxicity in rats: The role of apoptosis, gliosis, and aging markers

BACKGROUND

Prolonged lithium therapy in psychiatric disorders may be complicated by multi-organ dysfunction, particularly in the nervous system. Toxicity to the cerebellum is one of these, which, while uncommon, inevitably emerges negatively and permanently. Selenium is a trace element regarded as one of the critical antioxidants. Numerous investigations have validated selenium's neuroprotective properties against various neurotoxic medications. The degree of affliction of the nerve cells is assessed using GFAP, a marker of astrocytosis; Caspase-3, a marker of apoptosis; and klotho, a marker of anti-aging.

AIM OF THE STUDY

This study is designed to investigate the cerebellar structural and functional changes in lithium-treated rats and the postulated neuroprotective role of selenium.

METHODOLOGY

A total of 24 adult male albino rats were divided into 4 groups: control, selenium (1 mg/kg in water solution by gavage daily), lithium (by intraperitoneal injection of 25 mg/kg lithium carbonate dissolved in 0.9 % NaCL twice daily for 4 weeks), and lithium-selenium group. Motor coordination was evaluated using the rotarod test. Cerebellar malonaldehyde (MDA) and reduced glutathione (GSH) were measured, and histopathological examination and immunohistochemical expression of Klotho, GFAP, and Caspase 3 were evaluated.

RESULTS

The lithium-treated group exhibited reduced latency on the rotarod test, elevated oxidative stress indicators, and an altered cerebellar structure in HE and cresyl violet-stained sections. Moreover, there was a diminished Klotho expression and increased levels of both caspase-3 and GFAP expression. Selenium administration reduced latency time, diminished oxidative stress markers, mitigated lithium-induced cerebellar alterations, increased Klotho expression, and lowered the expression of caspase-3 and GFAP.

CONCLUSION

Lithium exposure causes alterations in the cerebellar cortical structure in albino rats. Selenium protected the cerebellar cortex from such changes by enhancing Klotho expression, diminishing oxidative stress, and reducing apoptosis.

Effect of antipsychotics on the focal adhesion pathway

Focal adhesions and their dynamic nature are essential for various physiological processes, including the formation of neurites, synaptic function and plasticity. Alterations in these processes have been associated with schizophrenia and bipolar disorder.

OBJECTIVES

This study aimed to explore the impact of pharmacological treatments used for bipolar disorder and schizophrenia on the expression of genes involved in the focal adhesion pathway, addressing a gap in understanding the interaction between medication effects and disease pathophysiology.

METHODS

NT2-N (neuron-like) cells were exposed to treatment with amisulpride, aripiprazole, chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone, or vehicle for 24 h. Genome-wide mRNA expression was analysed using gene set enrichment analysis.

RESULTS

The analysis revealed that seven out of the eight drugs widely prescribed for bipolar disorder and schizophrenia downregulate the expression of genes associated with the focal adhesions pathway. Focal adhesion was the pathway with the most negative normalised enrichment score across all treatments.

CONCLUSIONS

Our results support the hypothesis that focal adhesion pathways may play a role in the pathophysiology of bipolar disorder and schizophrenia. Moreover, the data underscore the importance of differentiating medication effects from disease mechanisms in psychiatric research, a challenge compounded by the medicated state of most study participants.

Effects of antipsychotic drugs on energy metabolism

Schizophrenia (SCZ) is a complex neuropsychiatric disorder associated with altered bioenergetic pathways and mitochondrial dysfunction. Antipsychotic medications, both first and second-generation, are commonly prescribed to manage SCZ symptoms, but their direct impact on mitochondrial function remains poorly understood. In this study, we investigated the effects of commonly prescribed antipsychotics on bioenergetic pathways in cultured neurons. We examined the impact of risperidone, aripiprazole, amisulpride, and clozapine on gene expression, mitochondrial bioenergetic profile, and targeted metabolomics after 24-h treatment, using RNA-seq, Seahorse XF24 Flux Analyser, and gas chromatography-mass spectrometry (GC-MS), respectively. Risperidone treatment reduced the expression of genes involved in oxidative phosphorylation, the tricarboxylic acid cycle, and glycolysis pathways, and it showed a tendency to decrease basal mitochondrial respiration. Aripiprazole led to dose-dependent reductions in various mitochondrial function parameters without significantly affecting gene expression. Aripiprazole, amisulpride and clozapine treatment showed an effect on the tricarboxylic acid cycle metabolism, leading to more abundant metabolite levels. Antipsychotic drug effects on mitochondrial function in SCZ are multifaceted. While some drugs have greater effects on gene expression, others appear to exert their effects through enzymatic post-translational or allosteric modification of enzymatic activity. Understanding these effects is crucial for optimising treatment strategies for SCZ. Novel therapeutic interventions targeting energy metabolism by post-transcriptional pathways might be more effective as these can more directly and efficiently regulate energy production.

Network-based drug repurposing for schizophrenia

Despite recent progress, the challenges in drug discovery for schizophrenia persist. However, computational drug repurposing has gained popularity as it leverages the wealth of expanding biomedical databases. Network analyses provide a comprehensive understanding of transcription factor (TF) regulatory effects through gene regulatory networks, which capture the interactions between TFs and target genes by integrating various lines of evidence. Using the PANDA algorithm, we examined the topological variances in TF-gene regulatory networks between individuals with schizophrenia and healthy controls. This algorithm incorporates binding motifs, protein interactions, and gene co-expression data. To identify these differences, we subtracted the edge weights of the healthy control network from those of the schizophrenia network. The resulting differential network was then analysed using the CLUEreg tool in the GRAND database. This tool employs differential network signatures to identify drugs that potentially target the gene signature associated with the disease. Our analysis utilised a large RNA-seq dataset comprising 532 post-mortem brain samples from the CommonMind project. We constructed co-expression gene regulatory networks for both schizophrenia cases and healthy control subjects, incorporating 15,831 genes and 413 overlapping TFs. Through drug repurposing, we identified 18 promising candidates for repurposing as potential treatments for schizophrenia. The analysis of TF-gene regulatory networks revealed that the TFs in schizophrenia predominantly regulate pathways associated with energy metabolism, immune response, cell adhesion, and thyroid hormone signalling. These pathways represent significant targets for therapeutic intervention. The identified drug repurposing candidates likely act through TF-targeted pathways. These promising candidates, particularly those with preclinical evidence such as rimonabant and kaempferol, warrant further investigation into their potential mechanisms of action and efficacy in alleviating the symptoms of schizophrenia.

Co-Expression Networks Unveiled Long Non-Coding RNAs as Molecular Targets of Drugs Used to Treat Bipolar Disorder

Long non-coding RNAs (lncRNAs) may play a role in psychiatric diseases including bipolar disorder (BD). We investigated mRNA-lncRNA co-expression patterns in neuronal-like cells treated with widely prescribed BD medications. The aim was to unveil insights into the complex mechanisms of BD medications and highlight potential targets for new drug development. Human neuronal-like (NT2-N) cells were treated with either lamotrigine, lithium, quetiapine, valproate or vehicle for 24 h. Genome-wide mRNA expression was quantified for weighted gene co-expression network analysis (WGCNA) to correlate the expression levels of mRNAs with lncRNAs. Functional enrichment analysis and hub lncRNA identification was conducted on key co-expressed modules associated with the drug response. We constructed lncRNA-mRNA co-expression networks and identified key modules underlying these treatments, as well as their enriched biological functions. Processes enriched in key modules included synaptic vesicle cycle, endoplasmic reticulum-related functions and neurodevelopment. Several lncRNAs such as GAS6-AS1 and MIR100HG were highlighted as driver genes of key modules. Our study demonstrates the key role of lncRNAs in the mechanism(s) of action of BD drugs. Several lncRNAs have been suggested as major regulators of medication effects and are worthy of further investigation as novel drug targets to treat BD.

Transcriptional Modulation of the Hippo Signaling Pathway by Drugs Used to Treat Bipolar Disorder and Schizophrenia

Recent reports suggest a link between positive regulation of the Hippo pathway with bipolar disorder (BD), and the Hippo pathway is known to interact with multiple other signaling pathways previously associated with BD and other psychiatric disorders. In this study, neuronal-like NT2 cells were treated with amisulpride (10 µM), aripiprazole (0.1 µM), clozapine (10 µM), lamotrigine (50 µM), lithium (2.5 mM), quetiapine (50 µM), risperidone (0.1 µM), valproate (0.5 mM), or vehicle control for 24 h. Genome-wide mRNA expression was quantified and analyzed using gene set enrichment analysis (GSEA), with genes belonging to Hippo, Wnt, Notch, TGF- β, and Hedgehog retrieved from the KEGG database. Five of the eight drugs downregulated the genes of the Hippo pathway and modulated several genes involved in the interacting pathways. We speculate that the regulation of these genes, especially by aripiprazole, clozapine, and quetiapine, results in a reduction of MAPK and NFκB pro-inflammatory signaling through modulation of Hippo, Wnt, and TGF-β pathways. We also employed connectivity map analysis to identify compounds that act on these pathways in a similar manner to the known psychiatric drugs. Thirty-six compounds were identified. The presence of antidepressants and antipsychotics validates our approach and reveals possible new targets for drug repurposing.