PPARD May Play a Protective Role for Major Depressive Disorder

Integration of non-targeted metabolomics with network pharmacology deciphers the anxiolytic mechanisms of Platycladi Semen extracts in CUMS mice

ETHNOPHARMACOLOGICAL RELEVANCE

Platycladi Semen was recorded in Shen Nong's Herbal Classic and was considered a herbal medicine with low toxicity after long-term medication. Multiple traditional Chinese medicine prescriptions containing Platycladi Semen have been used to treat insomnia. Modern clinical practitioners commonly use Platycladi Semen to treat anxiety disorders, but there are few studies on its composition and anxiolytic mechanisms.

AIM OF THE STUDY

To describe the main components of Platycladi Semen and investigate its anxiolytic effects and mechanisms.

MATERIALS AND METHODS

The main components of Platycladi Semen were characterized by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS). The anxiolytic effects of oral Platycladi Semen were evaluated in chronic unpredictable mild stress (CUMS) induced mice. To explore the anxiolytic mechanisms of Platycladi Semen, serum non-targeted metabolomics combined with network pharmacology and molecular docking was performed.

RESULTS

Fourteen compounds were identified in the 50% methanol extract and 11 fatty acid derivatives were identified in the methyl-esterified fatty oil of Platycladi Semen. In CUMS mice, both the aqueous extract and fatty oil of Platycladi Semen had anxiolytic effects, which were shown by the increase in the time and frequency of mice entering the open arm in the elevated plus maze (EPM) experiment. Through serum non-targeted metabolomics, 34 differential metabolites were identified, and lipid metabolic pathways such as sphingolipid metabolism, steroidogenesis, alpha-linoleic acid, and linoleic acid metabolism were enriched. Through network pharmacology, 109 targets of the main components in Platycladi Semen were identified, and the 'neuroactive ligand-receptor interaction' and 'lipid metabolism' were enriched. The molecular docking results showed that the main components in Platycladi Semen could bind to the key targets such as peroxisome proliferator-activated receptor delta (PPARD), peroxisome proliferator-activated receptor alpha (PPARA), fatty acid binding protein 5 (FABP5), fatty acid binding protein 3 (FABP3), peroxisome proliferator-activated receptor gamma (PPARG), arachidonate 5-lipoxygenase (ALOX5) and fatty acid amide hydrolase (FAAH).

CONCLUSION

This study indicated that Platycladi Semen has anxiolytic effects, and the anxiolytic mechanisms may be the regulation of lipid metabolism and the neuroactive ligand-receptor interaction.

The role of crm-1 in ionizing radiation-induced nervous system dysfunction in Caenorhabditis elegans

Ionizing radiation can cause changes in nervous system function. However, the underlying mechanism remains unclear. In this study, Caenorhabditis elegans (C. elegans) was irradiated with 75 Gy of ⁶⁰Co whole-body γ radiation. Behavioral indicators (head thrashes, touch avoidance, and foraging), and the development of dopaminergic neurons related to behavioral function, were evaluated to assess the effects of ionizing radiation on nervous system function in C. elegans. Various behaviors were impaired after whole-body irradiation and degeneration of dopamine neurons was observed. This suggests that 75 Gy of γ radiation is sufficient to induce nervous system dysfunction. The genes nhr-76 and crm-1, which are reported to be related to nervous system function in human and mouse, were screened by transcriptome sequencing and bioinformatics analysis after irradiation or sham irradiation. The expression levels of these two genes were increased after radiation. Next, RNAi technology was used to inhibit the expression of crm-1, a gene whose homologs are associated with motor neuron development in other species. Downregulation of crm-1 expression effectively alleviated the deleterious effects of ionizing radiation on head thrashes and touch avoidance. It was also found that the expression level of crm-1 was regulated by the nuclear receptor gene nhr-76. The results of this study suggest that knocking down the expression level of nhr-76 can reduce the expression level of crm-1, while down-regulating the expression level of crm-1 can alleviate behavioral disorders induced by ionizing radiation. Therefore, inhibition of crm-1 may be of interest as a potential therapeutic target for ionizing radiation-induced neurological dysfunction.

Novel Pharmacological Approaches to the Treatment of Depression

Major depressive disorder is one of the most prevalent mental health disorders. Monoamine-based antidepressants were the first drugs developed to treat major depressive disorder. More recently, ketamine and other analogues were introduced as fast-acting antidepressants. Unfortunately, currently available therapeutics are inadequate; lack of efficacy, adverse effects, and risks leave patients with limited treatment options. Efforts are now focused on understanding the etiology of depression and identifying novel targets for pharmacological treatment. In this review, we discuss promising novel pharmacological targets for the treatment of major depressive disorder. Targeting receptors including N-methyl-D-aspartate receptors, peroxisome proliferator-activated receptors, G-protein-coupled receptor 39, metabotropic glutamate receptors, galanin and opioid receptors has potential antidepressant effects. Compounds targeting biological processes: inflammation, the hypothalamic-pituitary-adrenal axis, the cholesterol biosynthesis pathway, and gut microbiota have also shown therapeutic potential. Additionally, natural products including plants, herbs, and fatty acids improved depressive symptoms and behaviors. In this review, a brief history of clinically available antidepressants will be provided, with a primary focus on novel pharmaceutical approaches with promising antidepressant effects in preclinical and clinical studies.