Antidepressive mechanisms of rhynchophylline in mice with chronic unpredictable stress-induced depression

Structural Characterization and Antidepressant-like Effects of Polygonum sibiricum Polysaccharides on Regulating Microglial Polarization in Chronic Unpredictable Mild Stress-Induced Zebrafish

Polysaccharides are one of the main active ingredients of Polygonum sibiricum (PS), which is a food and medicine homolog used throughout Chinese history. The antidepressant-like effects of PSP and its underlying mechanisms remain elusive, especially the regulation of microglial polarization. The current study determined the chemical composition and structural characteristics of PSP. Then, the chronic unpredictable mild stress (CUMS) procedure was carried out on the zebrafish for 5 weeks, and PSP was immersed for 9 days (1 h/d). The body weight of zebrafish was monitored, and behavioral tests, including the novel tank test and light and dark tank test, were performed to evaluate the antidepressant-like effects of PSP. Then, the function of the hypothalamic-pituitary-interrenal (HPI) axis, the levels of peripheral inflammation, neuronal and blood-brain barrier damage in the mesencephalon and telencephalon, and the mRNA expression of M1/M2 phenotype genes in the brain were examined. PSP samples had the typical structural characteristics of polysaccharides, consisting of glucose, mannose, and galactose, with an average Mw of 20.48 kDa, which presented porous and agglomerated morphologies. Compared with untreated zebrafish, the depression-like behaviors of CUMS-induced zebrafish were significantly attenuated. PSP significantly decreased the levels of cortisol and pro-inflammatory cytokines and increased the levels of the anti-inflammatory cytokines in the body of CUMS-induced depressive zebrafish. Furthermore, PSP remarkably reversed the neuronal and blood-brain barrier damage in the mesencephalon and telencephalon and the mRNA expression of M1/M2 phenotype genes in the brain. These findings indicated that the antidepressant-like effects of PSP were related to altering the HPI axis hyperactivation, suppressing peripheral inflammation, inhibiting neuroinflammation induced by microglia hyperactivation, and modulating microglial M1/M2 polarization. The current study provides the foundations for future examinations of PSP in the functional foods of emotional regulation.

Atractylenolide I improves behaviors in mice with depression-like phenotype by modulating neurotransmitter balance via 5-HT2A

To explore the antidepressant effects and targets of atractylenolide I (ATR) through a network pharmacological approach. Relevant targets of ATR and depression analyzed by network pharmacology were scored (identifying 5-HT2A targets). Through elevated plus maze, open field, tail suspension, and forced swimming tests, the behavioral changes of mice with depression (chronic unpredictable mild stress [CUMS]) were examined, and the levels of neurotransmitters including serotonin, dopamine, and norepinephrine (5-HT, DA, and NE) were determined. The binding of ATR to 5-HT2A was verified by small molecular-protein docking. ATR improved the behaviors of CUMS mice, elevated their levels of neurotransmitters 5-HT, DA, and NE, and exerted a protective effect on their nerve cell injury. After 5-HT2A knockout, ATR failed to further improve the CUMS behaviors. According to the results of small molecular-protein docking and network pharmacological analysis, ATR acted as an inhibitor by binding to 5-HT2A. ATR can improve the behaviors and modulate the neurotransmitters of CUMS mice by targeting 5-HT2A.

Rhynchophylline inhibits methamphetamine dependence via modulating the miR-181a-5p/GABRA1 axis

ETHNOPHARMACOLOGICAL RELEVANCE

Uncaria rhynchophylla (Miq.) Miq. ex Havil. is a plant species that is routinely devoted in traditional Chinese medicine to treat central nervous system disorders. Rhynchophylline (Rhy), a predominant alkaloid isolated from Uncaria rhynchophylla (Miq.) Miq. ex Havil., has been demonstrated to reverse methamphetamine-induced (METH-induced) conditioned place preference (CPP) effects in mice, rats and zebrafish. The precise mechanism is still poorly understood, thus further research is necessary.

AIM OF STUDY

This study aimed to investigate the role of miRNAs in the inhibitory effect of Rhy on METH dependence.

MATERIALS AND METHODS

A rat CPP paradigm and a PC12 cell addiction model were established. Microarray assays were used to screen and identify the candidate miRNA. Behavioral assessment, real-time PCR, dual-luciferase reporter assay, western blotting, stereotaxic injection of antagomir/agomir and cell transfection experiments were performed to elucidate the effect of the candidate miRNA and intervention mechanism of Rhy on METH dependence.

RESULTS

Rhy successfully reversed METH-induced CPP effect and the upregulated miR-181a-5p expression in METH-dependent rat hippocampus and PC12 cells. Moreover, suppression of miR-181a-5p by antagomir 181a reversed METH-induced CPP effect. Meanwhile, overexpression of miR-181a-5p by agomir 181a in combination with low-dose METH (0.5 mg/kg) elicited a significant CPP effect, which was blocked by Rhy through inhibiting miR-181a-5p. Finally, the result demonstrated that miR-181a-5p exerted its regulatory role by targeting γ-aminobutyric acid A receptor α1 (GABRA1) both in vivo and in vitro.

CONCLUSION

This finding reveals that Rhy inhibits METH dependence via modulating the miR-181a-5p/GABRA1 axis, which may be a promising target for treatment of METH dependence.