Standardized Citrus unshiu peel extract ameliorates dexamethasone-induced neurotoxicity and depressive-like behaviors in mice

Alterations of intestinal mucosal barrier, cecal microbiota diversity, composition, and metabolites of yellow-feathered broilers under chronic corticosterone-induced stress: a possible mechanism underlying the anti-growth performance and glycolipid metabolism disorder

This study aimed to explore alterations in growth performance, glycolipid metabolism disorders, intestinal mucosal barrier, cecal microbiota community, and metabolites in a chronic corticosterone (CORT)-induced stress (CCIS) broiler model. Results showed that compared with control (CON) broilers, in CCIS broilers: (i) the final body weight (BW), BW gain, and average daily gain were significantly reduced. (ii) The glycolipid metabolism disorder and impairement of intestinal immune barrier and physical barrier function were observed. (iii) Diversity and richness of cecal microbiota were obviously increased. From phylum to genus level, the abundances of Firmicutes and Faecalibacterium were significantly decreased, while the abundances of Proteobacteria, RuminococcaceaeUCG-005, and Escherichia coli (Shigella) were significantly increased. Microbial network analysis and function pathways prediction showed that cecal microbiota was mainly concentrated in translation, metabolism, nucleotide metabolism, and endocrine system. (iv) The main differential metabolites identified include steroids and their derivatives, amino acids, fatty acids, and carbohydrates; among which 37 metabolites were significantly upregulated, while 27 metabolites were significantly downregulated. These differential metabolites were mainly enriched in pathways related to steroid hormone biosynthesis and tyrosine metabolism. (v) Correlation between cecal microbiota and glycolipid metabolism indexes showed that BW and total cholesterol (TC) were positively correlated with Christensenellaceae_R.7_group and Escherichia_Shigella, respectively. Furthermore, the downregulated Faecalibacterium and Christensenellaceae were negatively correlated with the upregulated differentially expressed metabolites. These findings suggested that CCIS altered cecal microbiota composition and metabolites, which led to glycolipid metabolism disorder and impaired the nutritional metabolism and immune homeostasis, providing a theoretical basis for efforts to eliminate the harm of chronic stress to human health and animal production.

IMPORTANCE

The study aimed to determine the influence of altered intestinal mucosal barrier, cecum flora community, and metabolites on anti-growth performance, glycolipid metabolism disorders of chronic corticosterone (CORT)-induced stress (CCIS) broilers. Compared with control (CON) broilers, in CCIS broilers: (i) anti-growth performance, glycolipid metabolism disorder, and impaired intestinal immune barrier and physical barrier function were observed. (ii) From phylum to genus level, the abundances of Firmicutes and Faecalibacterium were decreased; whereas, the abundances of Proteobacteria, RuminococcaceaeUCG-005, and Escherichia coli (Shigella) were increased. (iii) Differential metabolites in cecum were mainly enriched in steroid hormone biosynthesis and tyrosine metabolism. (iv) Body weight (BW) and total cholesterol (TC) were positively correlated with Christensenellaceae_R.7_group and Escherichia_Shigella, respectively, while downregulated Faecalibacterium and Christensenellaceae were negatively correlated with upregulated metabolites. Our findings suggest that CCIS induces anti-growth performance and glycolipid metabolism disorder by altering cecum flora and metabolites, providing a theoretical basis for efforts to eliminate the effect of chronic stress on human health and animal production.

Citrus unshiu Peel Attenuates Dextran Sulfate Sodium-Induced Ulcerative Colitis in Mice due to Modulation of the PI3K/Akt Signaling Pathway and MAPK and NF-κB

Aim

Citrus unshiu peel has been used to treat various diseases in traditional East Asian medicine including Korea, and many studies have been reported regarding inflammatory diseases including ulcerative colitis (UC). However, the underlying mechanism by which Citrus unshiu peel modulates inflammation in UC remains unclear. Therefore, this study aimed to evaluate the therapeutic effect and underlying mechanism of Citrus unshiu peel water extract (CUP) for UC.

Methods

The experiment for UC was conducted with 8-week-old male Balb/c mice. After 1 week of adaptation, acute colitis was induced in all groups except the normal group by 5% DSS dissolved in drinking water for 1 week. Balb/c mice were divided into 5 groups (n = 8/group): control group (Control), distilled water-treated group (DSS), 100 mg/kg sulfasalazine-treated group (SASP), 100 mg/kg CUP-treated group (CUPL), and 200 mg/kg CUP-treated group (CUPH). The efficacy of CUP on UC was evaluated by biochemical analyses such as ROS and MPO in serum and MDA in tissues, and expression of proteins related to inflammation and apoptosis was evaluated through Western blot.

Results

As a result of confirming the macroscopic changes and H&E staining in colon tissues to confirm the preventive and therapeutic effects of CU, decrease in colon length and inflammatory lesions were inhibited in the CUP-treated group compared to the DSS group. In addition, as a result of serum ROS and tissue MDA analysis and oxidative stress-related protein analysis, it was significantly decreased in the CUP-administered group compared to the control group. In addition, treatment with CUP not only inactivated MAPK, p-IκBα, and NF-κBp65 by blocking the PI3K/Akt pathway but also significantly reduced the expression of inflammatory cytokines.

Conclusion

These results show that CUP not only suppresses oxidative stress in UC but also regulates inflammation-related proteins and apoptotic proteins by regulating the PI3K/Akt signaling pathway, suggesting that it has the potential as a material for developing new natural therapeutic agents for UC.

Phytowaste as nutraceuticals in boosting public health

The utilization of bioactive constituent of peels and seeds provide an effective, environment friendly and inexpensive therapy for different forms of human disease, and the production, improvement and documentation of novel nutraceuticals. This review systematically presents findings and further understanding of the reported benefits and therapeutic applications of peel and seed extracts on innovative cell culture and animal studies, as well as phased clinical human trial research. The extracts of seed and peels were reported to possess high quantities of bioactive substances with antioxidative, antidiabetic, hepatorenal protective, antithyroidal, anti-inflammatory, antibacterial, cardiovascular protective, neuro-protective effects, anticancer and wound healing activities. Therapeutic activities of the bioactive substances of peel and seed extracts include elevation of Superoxide dismutase (SOD), GSH-Px, t-GPx, Catalase and GST activities, with the suppression of MDA levels, hydroperoxide generation and lipid peroxidized products, the extracts also regulate inflammatory mediators and cytokines as they are reported to suppress the secretion of inflammatory cytokines, which include; IL-1β, PGE2, TGF-β and TNF-α and induces apoptosis and cell differentiation. This review revealed the therapeutic importance and best utilization of peels and seed extracts of fruits and vegetables.

Ninjinyoeito improves anxiety behavior in neuropeptide Y deficient zebrafish

Anxiety induced by excess mental or physical stress is deeply involved in the onset of human psychiatric diseases such as depression, bipolar disorder, and panic disorder. Recently, Kampo medicines have received focus as antidepressant drugs for clinical use because of their synergistic and additive effects. Thus, we evaluated the anxiolytic activity of Ninjinyoeito (NYT) using neuropeptide Y-knockout (NPY-KO) zebrafish that exhibit severe anxiety responses to acute stress. Adult NPY-KO zebrafish were fed either a 3% NYT-supplemented or normal diet (i.e., the control diet) for four days and were then examined via behavioral tests. After short-term cold stress (10 °C, 2 s) was applied, control-fed NPY-KO zebrafish exhibited anxiety behaviors such as freezing, erratic movement, and increased swimming time along the tank wall. On the other hand, NYT-fed NPY-KO zebrafish significantly suppressed these anxiety behaviors, accompanied by a downregulation of tyrosine hydroxylase levels and phosphorylation of extracellular signal-regulated kinases in the brain. To understand the responsible component(s) in NYT, twelve kinds of herbal medicines that composed NYT were tested in behavioral trials with the zebrafish. Among them, nine significantly reduced freezing behavior in NPY-KO zebrafish. In particular, Schisandra fruit induced the most potent effect on abnormal zebrafish behavior, even in the lower amount (0.3% equivalent to NYT), followed by Atractylodes rhizome and Cinnamon bark. Subsequently, four lignans uniquely found in Schisandra fruit (i.e., gomisin A, gomisin N, schizandrin, and schizandrin B) were investigated for their anxiolytic activity in NPY-KO zebrafish. As a result, schizandrin was identified as a responsible compound in the anxiolytic effect of NYT. These results suggest that NYT has a positive effect on mental stress-induced anxiety and may be a promising therapeutic for psychiatric diseases.

Dexamethasone Protects Against Ischaemic Brain Injury via Inhibiting the pAkt Signalling Pathway Through Increasing Hap1

Dexamethasone has been reported to reduce the infarct volume and protect neurological function after ischaemic injury, but the mechanism of Dex in brain injury is not clear. We aimed to study the mechanism by which dexamethasone protects against ischaemic brain injury. Western blotting was to detected the expression of Hap1,TrkB, Akt and Erk; TTC staining to analyse ischemic volume; neurological deficit evaluation to test degree of ischemic injury; immunofluorescence staining to analyse the distribution of Hap1; and the MCAO model was used to study these processes. All data are expressed as the means ± SEM and were analysed by GraphPad Prism 6. P < 0.05 was considered statistically significant. After dexamethasone (Dex) treatment, Hap1 levels were increased and peaked at 2 days; then, we found that body weight was decreased in Hap1-/+ mice. Further study showed that Dex treatment reduced the ischaemic volume and improved neurological function. Finally, we showed that Hap1 regulated the levels of pTrkB, pAkt and pErk 1/2 in ischaemic injury after Dex treatment. Our data suggest that dexamethasone protects against ischaemic brain injury by inhibiting the pAkt signalling pathway through increasing Hap1.

Chronic ethanol exposure induced depressive-like behavior in male C57BL/6 N mice by downregulating GluA1

Chronic ethanol exposure can increase the risk of depression. The α-amino-3‑hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor is a key factor in depression and its treatment. The study was conducted to investigate the depressive-like behavior induced by chronic ethanol exposure in mice and to explore the mechanism in cells. To establish the chronic ethanol exposure mouse model, male C57BL/6 N mice were administered 10% (m/V) and 20% (m/V) ethanol as the only choice for drinking for 60 days, 90 days and 180 days. Depressive-like behavior in mice was confirmed by the forced swimming test (FST). Ethanol-induced changes in the mouse hippocampus were indicated by Western blotting, qPCR and Fluoro-Jade C (FJC) staining. We confirmed that 90- and 180-day ethanol exposure can lead to depressive-like mouse behavior, cell apoptosis, neuronal degeneration, a reduction in GluA1 and brain-derived neurotrophic factor (BDNF) expression, and an increase in IL-6 and IL-1β in the mouse hippocampus. GluA1 silencing and overexpression models of SH-SY5Y cells were established for further investigation. The cells were treated with 100 mM and 200 mM ethanol for 24 h. Ethanol exposure decreased cell viability and the expression of BDNF and increased the cell apoptosis rate and the expression of BAX, cleaved caspase-3, IL-1β and IL-6. GluA1 silencing aggravated ethanol-induced changes in cell viability and apoptosis and the expression of BDNF, BAX and cleaved caspase-3, and GluA1 overexpression attenuated these changes. Neither the silencing nor overexpression of GluA1 had an effect on ethanol-induced increases in IL-1β and IL-6. Our results indicated that chronic ethanol exposure induced depressive-like behavior in male C57BL/6 N mice by downregulating GluA1 expression.

Repeated administration of a flavonoid-based formulated extract from citrus peels significantly reduces peripheral inflammation-induced pain in the rat

Depression-related disorders are the first cause of disability worldwide according to the World Health Organization, and there is limited availability of effective antidepressant medications without side effects. Similarly, pain management is a public health concern particularly due to the increase in use of opioid medications, which have a significant side effect profile. Flavonoids can modulate numerous physiological functions including emotional and anti-nociceptive processes. Gold lotion (GL) is a natural product based on the extract of six citrus peels rich in flavonoids (0.45 mg/ml) with numerous reported biological activities. In the present study, we investigated the effect of repeated administration of GL in a battery of behavioral tests, including the open field test (OFT), forced swim test (FST), and von Frey test (vFT), in rats. While the OFT measured anxiolytic-related effects, the FST evaluated depression-related behavior. The vFT evaluated mechanical allodynia in two rat models of peripheral inflammation induced by carrageenan or complete Freund's adjuvant (CFA) administration. Treatment with GL reduced mechanical allodynia after either carrageenan or CFA administration. On the other hand, repeated GL administration did not modulate any behavior evaluated by OFT or FST. Consumption of GL inhibits behavioral signs of inflammatory pain. Therefore, GL may be a valuable analgesic product to be used for inflammatory pain.

Administration of Asian Herb Bennet (Geum japonicum) Extract Reverses Depressive-Like Behaviors in Mouse Model of Depression Induced by Corticosterone

Geum japonicum, commonly known as Asian herb bennet, has been used as a diuretic, astringent, anti-dizziness, and anti-headache agent in traditional medicine. Since the antidepressant-like effects of G. japonicum extract have not been well studied, we examined the antidepressant-like effects of G. japonicum extract using depressive-like behavior induced in mice through daily injection of corticosterone (CORT). ICR mice (male, 8 weeks old) were treated with CORT (40 mg/kg, i.p.) and orally administered using oral gavage needles with G. japonicum extract (30, 100, and 300 mg/kg) for 4 weeks. Behavioral experiments were performed 1 h after administration. The control mice exhibited a significant increase in the immobility times in the tail suspension and forced swim tests as well as the step-through latency time in the passive avoidance test. Further, the control group showed a significant decrease in their sucrose consumption. However, treatment with G. japonicum extract at doses of 100 and 300 mg/kg significantly improved these depression-like behaviors without altering the locomotor activity. Moreover, treatment with G. japonicum extract significantly prevented the decrease in the expression of brain-derived neurotrophic factor (BDNF) in the hippocampus. In addition, G. japonicum extract had neuroprotective effects against CORT-induced neurotoxicity in SH-SY5Y cells. Our study indicates that G. japonicum extract exhibits antidepressant-like activity in CORT-induced depressive mice, which might be as a result of increased BDNF expression.

Citrus unshiu peel suppress the metastatic potential of murine melanoma B16F10 cells in vitro and in vivo

The peel of Citrus unshiu Marcow. fruits (CU) has long been used as a traditional medicine that has therapeutic effects against pathogenic diseases, including asthma, vomiting, dyspepsia, blood circulation disorders, and various types of cancer. In this study, we investigated the effect of CU peel on metastatic melanoma, a highly aggressive skin cancer, in B16F10 melanoma cells, and in B16F10 cells inoculated‐C57BL/6 mice. Our results show that ethanol extracts of CU (EECU) inhibited cell growth and increased the apoptotic cells in B16F10 cells. EECU also stimulated the induction of mitochondria‐mediated intrinsic pathway, with reduced mitochondrial membrane potential and increased generation of intracellular reactive oxygen species. Furthermore, EECU suppressed the migration, invasion, and colony formation of B16F10 cells. In addition, the oral administration of EECU reduced serum lactate dehydrogenase activity without weight loss, hepatotoxicity, nor nephrotoxicity in B16F10 cell‐inoculated mice. Moreover, EECU markedly suppressed lung hypertrophy, the number and expression of metastatic tumor nodules, and the expression of inflammatory tumor necrosis factor‐alpha in lung tissue. In conclusion, our findings suggest that the inhibitory effect of EECU on the metastasis of melanoma indicates that it may be regarded as a potential therapeutic herbal drug for melanoma.

Glucocorticoid-Driven NLRP3 Inflammasome Activation in Hippocampal Microglia Mediates Chronic Stress-Induced Depressive-Like Behaviors

Chronic stress is a key risk factor for depression, and microglia have been implicated in the pathogenesis of the disease. Recent studies show that the Nod-like receptor protein 3 (NLRP3) inflammasome is expressed in microglia and may play a crucial role in depression. However, the mechanism of NLRP3 inflammasome activation in hippocampal microglia and its role in depressive-like behaviors remain poorly understood. In this study, rats were subjected to 6 h of restraint stress per day for 21 days to produce a model of stress-induced depression. Behavioral tests and serum corticosterone were used to assess the success of the model. Furthermore, HAPI cells were pretreated with dexamethasone (5 × 10^-7 M) to assess stress-induced changes in microglial cells in culture. The microglial marker Iba-1, reactive oxygen species (ROS), nuclear factor kappa B (NF-κB) and key components of the NLRP3 inflammasome and its downstream inflammatory effectors (IL-1β and IL-18) were measured. Chronic stress induced depressive-like behavior, increased serum corticosterone levels and produced hippocampal structural changes. Chronic stress and dexamethasone both increased Iba-1 expression and ROS formation and also elevated levels of NF-κB, NLRP3, cleaved caspase-1, IL-1β and IL-18. After use of the NF-κB inhibitor BAY 117082 and knocked out NLRP3 in vitro decreased ROS formation and the expression of Iba-1, NF-κB and NLRP3 as well as levels of cleaved caspase-1, IL-1β and IL-18. These findings suggest that activation of the glucocorticoid receptor-NF-κB-NLRP3 pathway in hippocampal microglia mediates chronic stress-induced hippocampal neuroinflammation and depression-like behavior.