Sauchinone Blocks Ethanol Withdrawal-Induced Anxiety but Spares Locomotor Sensitization: Involvement of Nitric Oxide in the Bed Nucleus of the Stria Terminalis

Lavender essential oil alleviates depressive-like behavior in alcohol-withdrawn rats: Insights from gut metabolites and hippocampal transcriptome analysis

Lavender, an aromatic plant with a history dating back to ancient Egypt and Greece, is consumed because of its diverse pharmacological properties, including sedation, sleep aid, and antidepressant effects. However, the mechanisms underlying these antidepressant properties remain unclear. In this study, we explored the impact of lavender essential oil (LEO) inhalation on the diversity of gut microbiota, metabolites, and differential gene expression in the hippocampus of alcohol-withdrawn depressive rats. Additionally, we examined alterations in the hippocampal transient receptor potential (TRP) channel-mediated inflammatory regulation within the brain-gut axis of depressive rats. The results demonstrated a significant decrease in sucrose preference, diminished activity in the central zone of the open field test, and prolonged immobility time in the forced swim test in alcohol-withdrawn depressive rats, indicating the amelioration of depressive states following lavender essential oil inhalation. 16 S rDNA sequencing analysis revealed a significant reduction in Bacteroidota and Muribaculaceae in the gut of alcohol-withdrawn depressive rats, whereas lavender essential oil significantly increased the relative abundance of Muribaculaceae and other bacterial species. Metabolomic analysis identified 646 distinct metabolites as highly correlated biomarkers between the model and lavender essential oil groups. Furthermore, lavender essential oil inhalation significantly attenuated hippocampal inflammatory factors IL-2, IL-6, IL-1β, and TNF-α. This study identified elevated expression of Trpv4 and Calml4 in the hippocampal region of alcohol-withdrawn depressed rats and showed that lavender essential oil inhalation regulated aberrantly expressed genes. Our research suggests that lavender essential oil downregulates Trpv4, modulates inflammatory factors, and alleviates depressive-like behavior in alcohol withdrawal rats.

Salidroside ameliorates memory impairment following long-term ethanol intake in rats by modulating the altered intestinal microbiota content and hippocampal gene expression

Background

Salidroside (Sal), the main component of a famous herb Rhodiola rosea L, enhances memory performance and reduces fatigue. Therefore, this study assessed the effect of Sal on memory impairment induced by a long-term intake of ethanol (EtOH) in rats and investigated its relevant mechanisms using gut microbiota metagenomic analysis and hippocampal transcriptomic analysis.

Methods

Eighteen male SD rats were divided into the normal control group (CON group), EtOH model group (Model group), and Sal treatment group (Sal group). The rats in the Model and Sal groups intragastrically (i.g.) received 2 g/kg EtOH for 30 consecutive days, whereas the CON group was given an equal volume of distilled water. Meanwhile, the rats in the Sal group were administered i.g. 30 mg/kg Sal 60 min after EtOH intake. All rats were tested in the eight-arm maze for their memory function every 3 days. On the 30th day, metagenomic analyses of gut microbiota and transcriptomic analyses of the hippocampus were performed.

Results

Compared with the Model group, Sal treatment reduced the total time to complete the eight-arm maze task, decreased the number of arm entries, and abated the working memory error that was significant from the 9th day. Additionally, Sal intervention improved the gut microbiota composition, such as the increased abundance of Actinobacteria and Bifidobacterium, which was related to the metabolism of amino acids and terpenoid carbohydrate, endocrine function, and signal transduction by neurotransmitters. In the hippocampus, the EtOH intake differentially expressed 68 genes (54 genes increased, whereas 14 genes decreased), compared with the CON group, whereas Sal intervention affected these changes: 15 genes increased whereas 11 genes decreased. And, enrichment analyses revealed these genes were related to the structural components of the ribosome, mRNA splicing process, protein translation, mitochondria function, and immunological reaction. Finally, a correlation analysis found the memory impairment was positively correlated with the abnormal upregulation of Tomm7 but negatively correlated with decreased abundance of gut Alistipes_indistinctus, Lactobacillus_taiwanensis, Lactobacillus_paragasseri, and Lactobacillus johnsonii.

Conclusion

Sal improved memory impairment caused by long-term EtOH intake in rats, which may be related to its regulation of gut dysbiosis and hippocampal dysfunction.

Alterations and correlations of gut microbiota, fecal, and serum metabolome characteristics in a rat model of alcohol use disorder

Background

Growing evidence suggests the gut microbiota and metabolites in serum or fecal may play a key role in the process of alcohol use disorder (AUD). However, the correlations of gut microbiota and metabolites in both feces and serum in AUD subjects are not well understood.

Methods

We established a rat model of AUD by a chronic intermittent ethanol voluntary drinking procedure, then the AUD syndromes, the gut microbiota, metabolomic profiling in feces and serum of the rats were examined, and correlations between gut microbiota and metabolites were analyzed.

Results

Ethanol intake preference increased and maintained at a high level in experimental rats. Anxiety-like behaviors was observed by open field test and elevated plus maze test after ethanol withdraw, indicating that the AUD rat model was successfully developed. The full length 16S rRNA gene sequencing showed AUD significantly changed the β-diversity of gut microbial communities, and significantly decreased the microbial diversity but did not distinctly impact the microbial richness. Microbiota composition significantly changed in AUD rats, such as the abundance of Romboutsia and Turicibacter were significantly increased, whereas uncultured_bacterium_o_Mollicutes_RF39 was decreased. In addition, the untargeted metabolome analysis revealed that many metabolites in both feces and serum were altered in the AUD rats, especially involved in sphingolipid metabolism and glycerophospholipid metabolism pathways. Finally, multiple correlations among AUD behavior, gut microbiota and co-changed metabolites were identified, and the metabolites were directly correlated with the gut microbiota and alcohol preference.

Conclusion

The altered metabolites in feces and serum are important links between the gut microbiota dysbiosis and alcohol preference in AUD rats, and the altered gut microbiota and metabolites can be potentially new targets for treating AUD.

Solitary Nitric Oxide Signaling Mediates Mild Stress-Induced Anxiety and Norepinephrine Release in the Bed Nucleus of the Stria Terminalis during Protracted Ethanol Withdrawal

Ethanol withdrawal (EtOHW) alters the pattern of neurohormonal and behavioral response toward internal and external stimuli, which mediates relapse to alcohol use even after a long period of abstinence. Increased noradrenergic signaling from the nucleus tractus solitarius (NTS) to the bed nucleus of the stria terminalis (BNST) during EtOHW underlies withdrawal-induced anxiety, while nitric oxide synthase (NOS) inhibitors injected into the periaqueductal area attenuate EtOHW-induced anxiety. Therefore, this study investigated the involvement of NOS within the NTS in anxiety and increased norepinephrine (NE) release in the BNST during protracted EtOHW in rats exposed to a mild stress. Rats were intraperitoneally administered 3 g/kg/day EtOH for 21 days followed by 28 days of withdrawal, and on the 28^th day of withdrawal, the rats were subjected to restraint stress for 7 minutes. The elevated plus maze test was employed to evaluate anxiety-like behavior in rats, and in vivo microdialysis was used to measure the extracellular NE level in the BNST. In elevated plus maze tests, EtOHW rats but not EtOH-naive rats exhibited anxiety-like behavior when challenged with 7-minute mild restraint stress, which was, respectively, mitigated by prior intra-NTS infusion of the nitric oxide scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO), nonselective NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME), or selective neuronal NOS (nNOS) inhibitor 7-nitroindazole (7-NI). Each of these agents also decreased the plasma corticosterone levels in EtOHW rats. In in vivo microdialysis, prior intra-NTS infusion of carboxy-PTIO, L-NAME, or 7-NI attenuated the mild stress-induced NE release in the BNST of EtOHW rats. Additionally, EtOHW rats showed increased solitary nNOS gene and protein expression. Moreover, the anxiolytic effect of intra-NTS administration of 7-NI was abolished by subsequent intra-NTS administration of sodium nitroprusside. These results suggest that elevation of solitary nitric oxide signaling derived from nNOS mediates stress-precipitated anxiety and norepinephrine release in the BNST during protracted EtOHW.