Geraniol produces antidepressant-like effects in a chronic unpredictable mild stress mice model

Geraniol Ameliorates Pentylenetetrazol-Induced Epilepsy, Neuroinflammation, and Oxidative Stress via Modulating the GABAergic Tract: In vitro and in vivo studies

Introduction

Geraniol (Ger), a monoterpene, is a common constituent of several essential oils. This study explored the anticonvulsant effect of Ger in-vitro using nerve growth factor (NGF) prompted PC12 cell injured by Glutamate (Glu) and in-vivo using Pentylenetetrazole (PTZ)-induced kindling through the GABAergic pathway.

Materials

To assess the effect of Ger on NGF prompted PC12 cells injured by Glu, Ger at concentrations of 25, 50, 100, 200 and 400 μg/mL was used. GABA, 5-HT, IL-1β, IL-4, and TNF-α levels and the gene expressions of GABAA-Rα1, NMDAR1, GAD 65, GAD 67, GAT 1 and GAT 3 were measured in NGF-induced PC12 cells treated with Ger (100, and 200 μg/mL). Mice were randomly separated into five groups. Normal and PTZ groups in which mice were injected with saline or PTZ, respectively. PTZ + Ger 100, PTZ + Ger 200 and PTZ + SV groups in which mice orally administered Ger or sodium valproate (SV), respectively, then injected with PTZ.

Results

Ger up to 400 μg/mL did not display any toxicity or injury in PC12 cells. Ger (100 to 200 μg/mL) reduced the injury induced by Glu, increased the gene expression of GABAA-Rα1, GAD65 and GAD67 and decreased GAT 1, GAT 3 and NMDAR1 expression in NGF-induced PC12 cells damaged by Glu. Ger (100 to 200 μg/mL) increased GABA and reduced TNF-α, IL-4 and IL-1β levels in NGF-induced PC12 cells injured by Glu. As for the in-vivo results, Ger increased GABA, GAD, GAT 1 and 3 and lowered GABA T. Ger mitigated MDA, NO, IL-1β, IL-6, TNF-α and IFN-γ, GFAP, caspase-3, and -9 levels and Bax gene expression and escalated GSH, SOD, catalase, BDNF and Bcl2 gene expression.

Conclusion

Ger reduced the oxidative stress status, neuroinflammation and apoptosis and activated GABAergic neurotransmission, which might clarify its anticonvulsant. Ger protects animals against PTZ prompted kindling as established by the enhancement in short term as well as long-term memory. Ger mitigated the injury induced by Glu in NGF prompted PC12 cell.

Protective effects of geraniol in a male rat model of Alzheimer's disease: A behavioral, biochemical, and histological study

BACKGROUND

Alzheimer's disease (AD) as a neurodegenerative disease can cause behavioral impairments due to oxidative stress. Aging and oxidative conditions are some AD risk factors.

OBJECTIVE

We assessed the influence of geraniol (GR), an acyclic monoterpene alcohol, on behavioral functions, hippocampal oxidative status, and histological alterations in AD rats induced by amyloid-β (Aβ).

METHODS

Male Wistar rats (n = 70) were randomly allocated to the control, sham, AD, control-GR (100 mg/kg; per oral: P.O.), AD-GR (100 mg/kg; P.O.; treatment), GR-AD (100 mg/kg; P.O.; pretreatment), and GR-AD-GR (100 mg/kg; P.O.; pretreatment + treatment) groups. GR administration was done for four continuous weeks. After treatments, novel object recognition (NOR) and Morris water maze (MWM) tests assessed the animals' behavior. Then, hippocampal specimens were collected for biochemical assessment. Finally, the number of intact neurons was identified in the hippocampus using hematoxylin and eosin staining.

RESULTS

Aβ microinjection increased learning and memory deficits in both NOR and MWM tests, oxidative stress status, and neuronal loss. Oral GR administration improved behavioral deficits and reduced oxidative stress status and neuronal loss in the Aβ-infused animals.

CONCLUSIONS

GR ameliorates behavioral impairments through a decrease in neuronal degeneration and oxidative stress.

Geraniol (GER) attenuated chronic sleep restriction (CSR)-induced neuroinflammation in adolescent mice

Sleep insufficiency is a significant health problem worldwide, and adolescent sleep restriction (SR) could induce multiple neurodevelopmental disorders in the central nervous system (CNS). Microglial-mediated neuroinflammation plays a vital role in multiple neurological diseases, and recent research showed the regulation effect of immunoproteasome on microglia functions. Geraniol (GER), an important ingredient in many essential oils, possesses diverse pharmacological properties like anti-inflammatory and antioxidant. The present study was designed to evaluate the neuroprotective effect of GER on SR in adolescent mice and further investigate the underlying mechanisms. Our results displayed that 14 days of chronic sleep restriction (CSR) induced cognitive decline, and anxiety-like and attention-deficit behaviors, which were mitigated by GER pretreatment. GER administration also reversed microglial pro-inflammatory response under CSR stimulation in the anterior cingulate cortex (ACC) regions by reducing the expression and secretion of cytokines like IL-1β and TNF-α. Mechanism research showed that LMP7 mRNA was selectively up-regulated under CSR treatment but down-regulated by GER administration. Proteasome activity and protein expression of LMP7 were consistent with mRNA data. ONX-0914 was applied to inhibit LMP7 selectively, and data validated that GER might alleviate CSR-induced neuroinflammation by regulating LMP7. Our study provides evidence that LMP7 is a critical regulator of CSR-induced proinflammation, and geraniol might be a promising therapy against CSR-induced neurodevelopmental disorders.

Comparative Analysis of Hydrosol Volatile Components of Citrus × Aurantium 'Daidai' and Citrus × Aurantium L. Dried Buds with Different Extraction Processes Using Headspace-Solid-Phase Microextraction with Gas Chromatography-Mass Spectrometry

This work used headspace solid-phase microextraction with gas chromatography-mass spectrometry (HS-SPME-GC-MS) to analyze the volatile components of hydrosols of Citrus × aurantium 'Daidai' and Citrus × aurantium L. dried buds (CAVAs and CADBs) by immersion and ultrasound-microwave synergistic-assisted steam distillation. The results show that a total of 106 volatiles were detected in hydrosols, mainly alcohols, alkenes, and esters, and the high content components of hydrosols were linalool, α-terpineol, and trans-geraniol. In terms of variety, the total and unique components of CAVA hydrosols were much higher than those of CADB hydrosols; the relative contents of 13 components of CAVA hydrosols were greater than those of CADB hydrosols, with geranyl acetate up to 15-fold; all hydrosols had a citrus, floral, and woody aroma. From the pretreatment, more volatile components were retained in the immersion; the relative contents of linalool and α-terpineol were increased by the ultrasound-microwave procedure; and the ultrasound-microwave procedure was favorable for the stimulation of the aroma of CAVA hydrosols, but it diminished the aroma of the CADB hydrosols. This study provides theoretical support for in-depth exploration based on the medicine food homology properties of CAVA and for improving the utilization rate of waste resources.

Alcohol exacerbates psychosocial stress-induced neuropsychiatric symptoms: Attenuation by geraniol

Adaptation to psychosocial stress is psychologically distressing, initiating/promoting comorbidity with alcohol use disorders. Emerging evidence moreover showed that ethanol (EtOH) exacerbates social-defeat stress (SDS)-induced behavioral impairments, neurobiological sequelae, and poor therapeutic outcomes. Hence, this study investigated the effects of geraniol, an isoprenoid monoterpenoid alcohol with neuroprotective functions on EtOH escalated SDS-induced behavioral impairments, and neurobiological sequelae in mice. Male mice chronically exposed to SDS for 14 days were repeatedly fed with EtOH (2 g/kg, p. o.) from days 8-14. From days 1-14, SDS-EtOH co-exposed mice were concurrently treated with geraniol (25 and 50 mg/kg) or fluoxetine (10 mg/kg) orally. After SDS-EtOH translational interactions, arrays of behavioral tasks were examined, followed by investigations of oxido-inflammatory, neurochemicals levels, monoamine oxidase-B and acetylcholinesterase activities in the striatum, prefrontal-cortex, and hippocampus. The glial fibrillary acid protein (GFAP) expression was also quantified in the prefrontal-cortex immunohistochemically. Adrenal weights, serum glucose and corticosterone concentrations were measured. EtOH exacerbated SDS-induced low-stress resilience, social impairment characterized by anxiety, depression, and memory deficits were attenuated by geraniol (50 and 100 mg/kg) and fluoxetine. In line with this, geraniol increased the levels of dopamine, serotonin, and glutamic-acid decarboxylase enzyme, accompanied by reduced monoamine oxidase-B and acetylcholinesterase activities in the prefrontal-cortex, hippocampus, and striatum. Geraniol inhibited SDS-EtOH-induced adrenal hypertrophy, corticosterone, TNF-α, IL-6 release, malondialdehyde and nitrite levels, with increased antioxidant activities. Immunohistochemical analyses revealed that geraniol enhanced GFAP immunoreactivity in the prefrontal-cortex relative to SDS-EtOH group. We concluded that geraniol ameliorates SDS-EtOH interaction-induced behavioral changes via normalization of neuroimmune-endocrine and neurochemical dysregulations in mice brains.

Microwave-assisted enzymatic synthesis of geraniol esters in solvent-free systems: optimization of the reaction parameters, purification and characterization of the products, and biocatalyst reuse

Various geraniol esters act as insect pheromones and display pharmacological activities, especially as neuroprotective agents. Therefore, the search for synthetic strategies alternative to traditional chemical synthesis could help designing ecofriendly routes for the preparation of such bioactive compounds. Hence, this work aims at the microwave-assisted enzymatic synthesis of geranyl esters in solvent-free systems. The process variables were optimized for the synthesis of geranyl acetoacetate, achieving 85% conversion after 60 min using a 1:5 substrates molar ratio (ester to geraniol), 80 °C and 8.4% of Lipozyme 435 lipase without removal of the co-produced methanol. On the other hand, a 95% conversion was reached after 30 min using 1:6 substrates molar ratio, 70 °C and 7% lipase in the presence of 5Å molecular sieves for the methanol capture. In addition, the lipase showed good reusability, maintaining the same activity for five reaction cycles. Finally, under the above optimized conditions, other geraniol esters were successfully synthetized such as the geranyl butyrate (98%), geranyl hexanoate (99%), geranyl octanoate (98%), and geranyl (R)-3-hydroxybutyrate (56%). These results demonstrate the microwave-assisted lipase-catalyzed transesterification in a solvent-free system as an excellent and sustainable catalytic methodology to produce geraniol esters.

Chronic Stress-Induced Neuroinflammation: Relevance of Rodent Models to Human Disease

The brain is the central organ of adaptation to stress because it perceives and determines threats that induce behavioral, physiological, and molecular responses. In humans, chronic stress manifests as an enduring consistent feeling of pressure and being overwhelmed for an extended duration. This can result in a persistent proinflammatory response in the peripheral and central nervous system (CNS), resulting in cellular, physiological, and behavioral effects. Compounding stressors may increase the risk of chronic-stress-induced inflammation, which can yield serious health consequences, including mental health disorders. This review summarizes the current knowledge surrounding the neuroinflammatory response in rodent models of chronic stress-a relationship that is continually being defined. Many studies investigating the effects of chronic stress on neuroinflammation in rodent models have identified significant changes in inflammatory modulators, including nuclear factor-κB (NF-κB) and toll-like receptors (TLRs), and cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, and IL-6. This suggests that these are key inflammatory factors in the chronic stress response, which may contribute to the establishment of anxiety and depression-like symptoms. The behavioral and neurological effects of modulating inflammatory factors through gene knockdown (KD) and knockout (KO), and conventional and alternative medicine approaches, are discussed.

Gynura procumbens and selected metabolites: Amelioration of depressive-like behaviors in mice and risperidone-induced hyperprolactinemia in rats

Gynura procumbens (Lour.) Merr., utilized in traditional Chinese medicine, is known for its liver-protective, liver-soothing, and depression-alleviating properties. This research examines the antidepressant and anti-hyperprolactinemia potentials of an ethanol extract from G. procumbens stems (EEGS) and specific metabolites. To model depression and hyperprolactinemia, chronic unpredictable mild stress (CUMS) was induced in mice and risperidone was administered to rats, respectively. Treatments involved administering low (5 mg/kg), medium (25 mg/kg), and high (125 mg/kg) doses of EEGS and certain metabolites to both models. Behavioral assessments were conducted in the CUMS-induced mice, while the CA3 neuronal damage in mice and histopathological alterations in rat mammary glands were evaluated using Nissl and Hematoxylin & Eosin staining techniques, respectively. EEGS decreased immobility times in the forced swimming and tail suspension tests in mice, enhancing their exploration of the central zone. It elevated the serum levels of 5-hydroxytryptamine, norepinephrine, estradiol, luteinizing hormone (LH), and testosterone in mice. Moreover, EEGS restored the neuronal cell arrangement in the CA3 area, reduced interleukin-1beta mRNA production, and increased the expression of interleukin-10 and beta-catenin mRNA. In the context of risperidone-induced hyperprolactinemia, EEGS lowered blood prolactin levels, reduced the dimensions of rat nipples, and enhanced LH, progesterone, and dopamine levels, alongside mitigating mammary hyperplasia. Among the EEGS selected metabolites, the combined effect of chlorogenic acid and trans-p-coumaric acid was found to be more effective than the action of each compound in isolation. Collectively, the findings indicate that EEGS and its selected metabolites offer promising antidepressant benefits while counteracting hyperprolactinemia.

Neuropharmacological assessment and identification of possible lead compound (apomorphine) from Hygrophila spinosa through in-vivo and in-silico approaches

The aim of this research is to examine possible neurological activity of methanol, ethyl acetate, and aqueous extracts of Hygrophila spinosa and identify possible lead compounds through in silico analysis. In vivo, neuropharmacological activity was evaluated by using four distinct neuropharmacological assessment assays. Previously reported GC-MS data and earlier literature were utilized to identify the phytochemicals present in Hygrophila spinosa. Computational studies notably molecular docking and molecular dynamic simulations were conducted with responsible receptors to assess the stability of the best interacting compound. Pharmacokinetics properties like absorption, distribution, metabolism, excretion, and toxicity were considered to evaluate the drug likeliness properties of the identified compounds. All the in vivo results support the notion that different extracts (methanol, ethyl acetate, and aqueous) of Hygrophila spinosa have significant (*p = 0.05) sedative-hypnotic, anxiolytic, and anti-depressant activity. Among all the extracts, specifically methanol extracts of Hygrophila spinosa (MHS 400 mg/kg.b.w.) showed better sedative, anxiolytic and antidepressant activity than aqueous and ethyl acetate extracts. In silico molecular docking analysis revealed that among 53 compounds 7 compounds showed good binding affinities and one compound, namely apomorphine (CID: 6005), surprisingly showed promising binding affinity to all the receptors . An analysis of molecular dynamics simulations confirmed that apomorphine (CID: 6005) had a high level of stability at the protein binding site. Evidence suggests that Hygrophila spinosa has significant sedative, anxiolytic, and antidepressant activity. In silico analysis revealed that a particular compound (apomorphine) is responsible for this action. Further research is required in order to establish apomorphine as a drug for anxiety, depression, and sleep disorders.Communicated by Ramaswamy H. Sarma.

Pogostemon cablin essential oil affects anxiety- and depressive-like behaviors and the gut microbiota in chronic unpredictable mild stress model rats

The gut microbiota is thought to be an important factor that influences brain processes and behaviors through the gut-brain axis. Pogostemon cablin is used in traditional Chinese medicine (TCM) to treat gastrointestinal symptoms. Patchouli essential oil (PCO), the main active agent in P. cablin, is used in aromatherapy for stress relief. The aim of our study was to investigate the effects of orally administered PCO on anxiety- and depressive-like behaviors and the gut microbiota. We constructed a rat model of chronic unpredictable mild stress (CUMS) and explored the anxiolytic- and antidepressant-like effects of PCO using the open field test (OFT) and forced swim test (FST). Changes in the abundance of the gut microbiota, short-chain fatty acids (SCFAs), and other related molecules were assessed to determine the role of the gut microbiota. Our results showed that CUMS induced an anxiety-like phenotype in the OFT, which was reversed by PCO, and that PCO also significantly mitigated the depression-like behaviors caused by CUMS in the FST. Furthermore, we found that PCO increased the relative abundances of several probiotics, including Bacteroides and Blautia, and decreased the relative abundances of Ruminococcus_1 and Ruminococcus_2, which were increased by CUMS. Regarding SCFAs, the metabolites of the gut microbiota, PCO increased the concentration of propionic acid and decreased that of caproic acid. Finally, PCO restored the serotonin (5-hydroxytryptamine, 5-HT) level in the hippocampus, which had been decreased by CUMS. The results of this study suggested that PCO can improve stress-related anxiety- and depression-like behaviors and might exert its effects on the central nervous system through interactions with the gut microbiota.

Chemical Composition and Potential Antimicrobial and Anti-Inflammatory Activities of Essential Oil from Fruits of Alpinia zerumbet (Pers.) B.L.Burtt & R.M.Sm

Alpinia zerumbet (Pers.) B.L.Burtt & R.M.Sm. was extensively used in traditional medicine for its several properties, but continuous investigation is needed to discover the properties of its essential oils (EOs). This work evaluated the properties of an EO obtained by steam distillation (named ESD) as well as extracts obtained by petroleum ether (named EP) both from Alpinia zerumbet fruits. Gas chromatography-mass spectrometry (GC-MS) was chosen to identify the composition, and eleven compounds were identified as the main components of the EO and EP of Alpinia zerumbet fruits. The antimicrobial properties were investigated by minimum inhibitory concentration (MIC) and the inhibition area. The results identified the differences in antimicrobial activities attributed to different extraction methods. Enzyme-linked immunosorbent assay (ELISA) and Western Blot (WB) assay were conducted to assess the anti-inflammatory effects of ESD. In conclusion, our study suggested that EO from Alpinia zerumbet fruits might be a prospective candidate for antimicrobial and anti-inflammatory therapy.

Probiotics for the treatment of depression and its comorbidities: A systemic review

Depression is one of the most common psychiatric conditions, characterized by significant and persistent depressed mood and diminished interest, and often coexists with various comorbidities. The underlying mechanism of depression remain elusive, evidenced by the lack of an appreciate therapy. Recent abundant clinical trials and animal studies support the new notion that the gut microbiota has emerged as a novel actor in the pathophysiology of depression, which partakes in bidirectional communication between the gut and the brain through the neuroendocrine, nervous, and immune signaling pathways, collectively known as the microbiota-gut-brain (MGB) axis. Alterations in the gut microbiota can trigger the changes in neurotransmitters, neuroinflammation, and behaviors. With the transition of human microbiome research from studying associations to investigating mechanistic causality, the MGB axis has emerged as a novel therapeutic target in depression and its comorbidities. These novel insights have fueled idea that targeting on the gut microbiota may open new windows for efficient treatment of depression and its comorbidities. Probiotics, live beneficial microorganisms, can be used to modulate gut dysbiosis into a new eubiosis and modify the occurrence and development of depression and its comorbidities. In present review, we summarize recent findings regarding the MGB axis in depression and discuss the potential therapeutic effects of probiotics on depression and its comorbidities.

Geraniol improves passive avoidance memory and hippocampal synaptic plasticity deficits in a rat model of Alzheimer's disease

Alzheimer's disease (AD) is the most progressive and irreversible neurodegenerative disease that leads to synaptic loss and cognitive decline. The present study was designed to evaluate the effects of geraniol (GR), a valuable acyclic monoterpene alcohol, with protective and therapeutic effects, on passive avoidance memory, hippocampal synaptic plasticity, and amyloid-beta (Aβ) plaques formation in an AD rat model induced by intracerebroventricular (ICV) microinjection of Aβ_1-40. Seventy male Wistar rats were randomly into sham, control, control-GR (100 mg/kg; P.O. (orally), AD, GR-AD (100 mg/kg; P.O.; pretreatment), AD-GR (100 mg/kg; P.O.; treatment), and GR-AD-GR (100 mg/kg; P.O.; pretreatment & treatment). Administration of GR was continued for four consecutive weeks. Training for the passive avoidance test was carried out on the 36^th day and a memory retention test was performed 24 h later. On day 38, hippocampal synaptic plasticity (long-term potentiation; LTP) was recorded in perforant path-dentate gyrus (PP-DG) synapses to assess field excitatory postsynaptic potentials (fEPSPs) slope and population spike (PS) amplitude. Subsequently, Aβ plaques were identified in the hippocampus by Congo red staining. The results showed that Aβ microinjection increased passive avoidance memory impairment, suppressed of hippocampal LTP induction, and enhanced of Aβ plaque formation in the hippocampus. Interestingly, oral administration of GR improved passive avoidance memory deficit, ameliorated hippocampal LTP impairment, and reduced Aβ plaque accumulation in the Aβ-infused rats. The results suggest that GR mitigates Aβ-induced passive avoidance memory impairment, possibly through alleviation of hippocampal synaptic dysfunction and inhibition of Aβ plaque formation.

Research progress of traditional Chinese medicine compound "Xiaochaihu Decoction" in the treatment of depression

Depression is a common psychiatric disorder under the category of depression syndrome in Traditional Chinese Medicine (TCM) theory. Meanwhile, Xiaochaihu Decoction is a classical TCM formulation regulating Qi, resolving and dissipating stagnation. Clinically, the formulation has long been adopted to treat Shaoyang stagnation syndrome for depression syndrome. In this review, potential targets of action and the corresponding pathways of Xiaochaihu Decoction are explored for depression treatment via network pharmacology. The article also systematically summarizes the active components and pharmacological mechanisms of seven Chinese herbal medicine components in Xiaochaihu Decoction and guides the future study direction of Xiaochaihu Decoction, which may serve a promising treatment for depression.

Nootkatone Improves Chronic Unpredictable Mild Stress-Induced Depressive-Like Behaviors by Repressing NF-κB/NLRP3-Mediated Neuroinflammation

OBJECTIVE

To explore the effect of nootkatone (NKT) on chronic unpredictable mild stress (CUMS)-induced depressive-like behaviors and the mechanism underlying NKT improving the depressive-like behaviors.

METHODS

The CUMS-induced depression model was established in mice. Fifty mice were randomized into 5 groups (n=10) in accordance with a random number table: control group, CUMS group, CUMS + NKT (6 mg/kg) group, CUMS + NKT (12 mg/kg) group, and CUMS + ketamine group. From the 22th day, NKT (6 or 12 mg/kg) or ketamine (0.5 mg/kg) was given with intragastric administration every day for 21 days. Behavioral tests including forced swimming test (FST), tail suspension test (TST), sucrose preference test (SPT) and open-field test (OFT) were carried out. The mRNA and protein expressions of interleukin (IL)-1β, IL-18, IL-6, and tumor necrosis factor (TNF)-α in hippocampus were assessed using quantitative realtime polymerase chain reaction (PCR), Western blot analysis, and enzyme linked immunosorbent assay. The nuclear factor-κB (NF-κB)/NOD-like receptor 3 (NLRP3) inflammasome pathway was analyzed using Western blot and immunofluorescence analysis.

RESULTS

NKT treatment improved CUMS-induced depressive-like behaviors in mice (P<0.05 or P<0.01). NKT significantly decreased the mRNA and protein levels of IL-1β, IL-18, IL-6, and TNF-α in hippocampus of CUMS mice (P<0.05 or P<0.01). Furthermore, NKT repressed CUMS-induced activation of NF-κB signaling and NLRP3 inflammasome (P<0.01). More important, Nigericin, a NLRP3 activator, destroyed the effect of NKT on repressing neuroinflammation and improving depressive-like behaviors (P<0.05 or P<0.01).

CONCLUSION

NKT ameliorates the depressive-like symptoms, in part by repressing NF-κB/NLRP3-mediated neuroinflammation.

The NLRP3 inflammasome in depression: Potential mechanisms and therapies

Increasing evidence suggests that the failure of clinical antidepressants may be related with neuroinflammation. The NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome is an intracellular multiprotein complex, and has been considered as a key contributor to the development of neuroinflammation. Inhibition of NLRP3 inflammasome is an effective method for depression treatment. In this review, we summarized current researches highlighting the role of NLRP3 inflammasome in the pathology of depression. Firstly, we discussed NLRP3 inflammasome activation in patients with depression and animal models. Secondly, we outlined the possible mechanisms driving the activation of NLRP3 inflammasome. Thirdly, we discussed the pathogenetic role of NLRP3 inflammasome in depression. Finally, we overviewed the current and potential antidepressants targeting the NLRP3 inflammasome. Overall, the inhibition of NLRP3 inflammasome activation may be a potential therapeutic strategy for inflammation-related depression.

Essential oils prolonged the cut carnation longevity by limiting the xylem blockage and enhancing the physiological and biochemical levels

Postharvest characteristics, such as vase life and antimicrobial preservation of commercial cut flowers are some of the major determinants of their market value worldwide. Extending vase life while restricting microbial proliferation in cut flowers is an important challenge faced by floricultural researchers. This study evaluates the preservative efficiency of different essential oils used as additive solutions in prolonging the longevity of carnation cv. Madam Collette cut flowers and restricting microbial growth in them. Cut carnations were treated with four essential oils: geranium, thyme, marjoram, and anise at concentrations of 0, 25, 50, and 75 mg/L. While treatment with all the essential oils prolonged the longevity of the cut flowers, thyme and marjoram oils were most effective at concentrations of 50 mg/L each. The vase life of thyme-treated and marjoram-treated carnations almost doubled to 18.5 days and 18.25 days, respectively, as compared to untreated flowers. Treatment with essential oils also led to an increase in water uptake by the cut flowers enhancing their relative water content (RWC). It also restricted the sharp decline of chlorophyll and total carbohydrates content of the flowers during their vase life period. Morphological features of the stem bases of treated and untreated carnations were analyzed using scanning electron microscopy (SEM). The stem ends of geranium and anise-treated carnations showed less bacterial growth than untreated flowers and no apparent xylem blockage was observed even after nine days of treatment. Furthermore, the presence of essential oils also reduced lipid peroxidation and free radical generation as observed by malondialdehyde (MDA) and H2O2 quantification, respectively. It also led to increased production of total phenols leading to enhanced membrane stability. The use of thyme and marjoram essential oils as antimicrobial preservatives and green antioxidants appears to have promising applications in both the industrial and scientific sectors.

How Oxidative Stress Induces Depression?

Depression increasingly affects a wide range and a large number of people worldwide, both physically and psychologically, which makes it a social problem requiring prompt attention and management. Accumulating clinical and animal studies have provided us with substantial insights of disease pathogenesis, especially central monoamine deficiency, which considerably promotes antidepressant research and clinical treatment. The first-line antidepressants mainly target the monoamine system, whose drawbacks mainly include slow action and treatment resistant. The novel antidepressant esketamine, targeting on central glutamatergic system, rapidly and robustly alleviates depression (including treatment-resistant depression), whose efficiency is shadowed by potential addictive and psychotomimetic side effects. Thus, exploring novel depression pathogenesis is necessary, for seeking more safe and effective therapeutic methods. Emerging evidence has revealed vital involvement of oxidative stress (OS) in depression, which inspires us to pursue antioxidant pathway for depression prevention and treatment. Fully uncovering the underlying mechanisms of OS-induced depression is the first step towards the avenue, thus we summarize and expound possible downstream pathways of OS, including mitochondrial impairment and related ATP deficiency, neuroinflammation, central glutamate excitotoxicity, brain-derived neurotrophic factor/tyrosine receptor kinase B dysfunction and serotonin deficiency, the microbiota-gut-brain axis disturbance and hypothalamic-pituitary-adrenocortical axis dysregulation. We also elaborate on the intricate interactions between the multiple aspects, and molecular mechanisms mediating the interplay. Through reviewing the related research progress in the field, we hope to depict an integral overview of how OS induces depression, in order to provide fresh ideas and novel targets for the final goal of efficient treatment of the disease.

Microglia Involves in the Immune Inflammatory Response of Poststroke Depression: A Review of Evidence

Poststroke depression (PSD) does not exist before and occurs after the stroke. PSD can appear shortly after the onset of stroke or be observed in the weeks and months after the acute or subacute phase of stroke. The pathogenesis of PSD is unclear, resulting in poor treatment effects. With research advancement, immunoactive cells in the central nervous system, particularly microglia, play a role in the occurrence and development of PSD. Microglia affects the homeostasis of the central nervous system through various factors, leading to the occurrence of depression. The research progress of microglia in PSD has been summarized to review the evidence regarding the pathogenesis and treatment target of PSD in the future.

Sortilin deletion in the prefrontal cortex and hippocampus ameliorates depressive-like behaviors in mice via regulating ASM/ceramide signaling

Major depressive disorder (MDD) is a common psychiatric disorder characterized by persistent mood despondency and loss of motivation. Although numerous hypotheses have been proposed, the possible pathogenesis of MDD remains unclear. Several recent studies show that a classic transporter protein, sortilin, is closely associated with depression. In the present study, we investigated the role of sortilin in MDD using a well-established rodent model of depression. Mice were subjected to chronic unpredictable mild stress (CUMS) for 6 weeks. We showed that the expression levels of sortilin were significantly increased in the prefrontal cortex and hippocampus of CUMS mice. The depressive-like behaviors induced by CUMS were alleviated by specific knockdown of sortilin in the prefrontal cortex and hippocampus. We revealed that sortilin facilitated acid sphingomyelinase (ASM)/ceramide signaling, which activated RhoA/ROCK2 signaling, ultimately causing the transformation of dendritic spine dynamics. Specific overexpression of sortilin in the prefrontal cortex and hippocampus induced depressive-like behaviors, which was mitigated by injection of ASM inhibitor SR33557 (4 µg/μL) into the prefrontal cortex and hippocampus. In conclusion, sortilin knockdown in the prefrontal cortex and hippocampus plays an important role in ameliorating depressive-like behavior induced by CUMS, which is mainly evidenced by decreasing the trafficking of ASM from the trans-Golgi network to the lysosome and reducing the ceramide levels. Our results provide a new insight into the pathology of depression, and demonstrate that sortilin may be a potential therapeutic target for MDD.

Neuroprotective effect of geraniol on neurological disorders: a review article

BACKGROUND

Neurological disorders are structural, biochemical, and electrical abnormalities that affect the peripheral and central nervous systems. Paralysis, muscle weakness, tremors, spasms, and partial or complete loss of sensation are some symptoms of these disorders. Neurorehabilitation is the main treatment for neurological disorders. Treatments can improve the quality of life of patients. Neuroprotective substances of natural origin are used for the treatments of these disorders.

METHODS AND RESULTS

Online databases, such as Google Scholar, PubMed, ScienceDirect, and Scopus were searched to evaluate articles from 1981-2021 using the Mesh words of geraniol (GER), neurological disorders, epilepsy, spinal cord injury (SCI), Parkinson's diseases (PD), and depression. A total of 87 studies were included in this review. GER with antioxidant, anti-inflammatory, and neuroprotective effects can improve the symptoms and reduce the progression of neurological diseases. GER exhibits neuroprotective effects by binding to GABA and glycine receptors as well as by inhibiting the activation of nuclear factor kappa B (NF-κB) pathway and regulating the expression of nucleotide-binding oligomerization of NLRP3 inflammasome. In this study, the effect of GER was investigated on neurological disorders, such as epilepsy, SCI, PD, and depression.

CONCLUSION

Although the medicinal uses of GER have been reported, more clinical and experimental studies are needed to investigate the effect of using traditional medicine on improving lifethreatening diseases and the quality of life of patients.

Mechanistic insight of the potential of geraniol against Alzheimer's disease

Background

Alzheimer’s disease (AD) as a neurodegenerative disease occupies 3/5–4/5 cases among patients with dementia, yet its pathogenetic mechanism remains unclear. Geraniol, on the other hand, is a well-known extract from essential oils of aromatic plants and has been proven that it has outstanding neuroprotective effects as well as ameliorating influence in memory impairment. Therefore, the present study aims to elucidate the potential of geraniol against AD by network pharmacology-based approach combined with molecular modeling study.

Materials and methods

Firstly, we evaluated the druggability of geraniol by ADME method. Then, we obtained the geraniol targets and AD-related targets from multiple open data sources. Afterward, we calculated the intersection through a Venn diagram to find common targets, and via Panther classification system to categorize them. In order to gain a macroscopic understanding of these common targets, we carried out GO terms and KEGG pathways enrichment analyses, according to which we constructed a compound–target–pathway–disease network. In addition, we built a preliminary PPI network which was further analyzed both functionally and topologically. Consequently, five hub targets were sorted out. Finally, we conducted molecular docking and molecular dynamic simulation to validate our findings.

Results

In the present study, the pharmacological properties of geraniol were assessed according to ADME and Lipinski’s rule, which demonstrate promising druggability. Then, from 10,972 AD-related targets and 33 geraniol targets, 29 common targets were identified, among which 38.1% of them are metabolite interconversion enzymes, 23.8% are protein modifying enzymes, 33.3% are transmembrane receptors, and the rest are transporters. Enrichment analyses hint that geraniol is involved in cholinergic synapse, serotonergic synapse, and neuroactive ligand–receptor interaction. We also built a preliminary PPI network to investigate the interplay between these targets and their extensive interactions. Then, by functionally clustering the preliminary PPI network, we gained a cluster of proteins which formed a subnetwork with score of 8.476, and 22 nodes. Its results of GO terms and KEGG pathways enrichment analyses once again suggests that geraniol actively participates in cholinergic synapse, serotonergic synapse, and neuroactive ligand–receptor interaction, which are believed to be strongly associated with AD pathogenesis. Besides, topological analyses of the preliminary PPI network helped find 5 hub targets (i.e., CHRM3, PRKCA, PRKCD, JAK1, JAK2). To verify their interaction with geraniol molecule, we conducted molecular docking, and found that CHRM3 possesses the highest affinity in binding, indicating that geraniol molecules are closely bound to each hub target, and CHRM3 may serve as a key target of geraniol against AD. It was then further confirmed by molecular dynamic simulation, the result of which supports our hypothesis.

Conclusion

The present study shares a mechanistic insight of the potential of geraniol against AD, giving a reference to future experimental studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-022-00699-8.

Antidepressant-like Activity of Patchouli Oil var. Tapak Tuan (Pogostemon cablin Benth) via Elevated Dopamine Level: A Study Using Rat Model

Essential oils are gaining popularity for their use in treating depression, including that extracted from patchouli leaves and stems (Pogostemon cablin). Herein, we used patchouli oil (PO) containing a high amount of patchouli alcohol derived from P. cablin var. Tapak Tuan. The aim of this study was to investigate the antidepressant potential of PO, with a variety of patchouli alcohol concentrations obtained from a separation process using vacuum distillation with different temperature ranges. The initial patchouli oil (iPO) was traditionally distilled by a local farmer and further distilled using a rotary evaporator at temperature ranges of 115−160 °C (POF-1); 120−160 °C (POF-2), and 125−160 °C (POF-3), resulting in products with different patchouli alcohol concentrations. POF-3, with the highest patchouli alcohol content of 60.66% (based on gas chromatography-mass spectrometry), was used for cooling crystallization, resulting in 100% patchouli alcohol crystal (pPA). A tail suspension test (TST) was performed on a rat model to screen the antidepressant potential of iPO and its derivatives. The TST results revealed that POF-3 had the best antidepressant-like effect and was second only to the fluoxetine-based antidepressant, Kalxetin®, where both groups had significant reductions of immobility time post-treatment (p < 0.0001). Other than patchouli alcohol, POF-3 also contained ledol and trans-geraniol, which have been reported for their antidepressant-related activities. Brain dopamine levels increased significantly in the group treated with POF-3 (p < 0.05 as compared with the control group), suggesting its primary anti-depressant mechanism. These findings suggest the potential of vacuum-distilled patchouli oil in reducing depression via dopamine elevation.

Correlation between intestinal microbiotal imbalance and 5-HT metabolism, immune inflammation in chronic unpredictable mild stress male rats

To explore the role of intestinal microbiota on the occurrence of depression-like behavior. Twenty male adult Wistar rats were randomly divided into control and experimental groups. Depression-like behavior of the rats was validated using sucrose preference test (SPT) and forced swimming test (FST) after chronic unpredictable mild stress (CUMS) for 3 weeks. Fecal microbiota was analyzed through 16S rRNA sequence analysis. The levels of 5-HT and inflammatory factors in the colon, brain and sera were measured using enzyme-linked immunosorbent assay (ELISA), quantitative PCR (qPCR) and western blotting analyses. The percentage of different types of immune cells in the peripheral blood was determined through flow cytometry. CUMS caused depression-like symptoms, including anhedonia and desperate behavior. Significant differences were found in the structure and abundance of intestinal microbiota. CUMS intervention significantly increased the levels of 5-HT and Tph1 in the colon and decreased the level of Scl6a4. The concentrations of 5-HT and Tph2 in the prefrontal and hippocampal tissues were lower, while IDO1 was higher. Certain cytokines, such as IL-6, IL-1 and TNF-ɑ, were significantly elevated in peripheral blood, while the percentage of CD3⁺ CD4⁺ double-positive cells and CD4⁺ /CD8⁺ ratio were downregulated in the CUMS group. Pearson correlation analysis showed that intestinal microbiota was significantly associated with not only the metabolism of 5-HT in intestinal and brain tissues, but also with the proportion of immune cells and certain cytokines. Stress can lead to disturbances in the intestinal microbial structure, which may contribute to depression by interfering with 5-HT metabolism and immune inflammatory responses.

Geraniol Ameliorates Doxorubicin-Mediated Kidney Injury through Alteration of Antioxidant Status, Inflammation, and Apoptosis: Potential Roles of NF-κB and Nrf2/Ho-1

Doxorubicin-mediated kidney impairment is a serious problem in cancer treatment. Accordingly, this work investigated the ability of geraniol to modulate doxorubicin-induced kidney damage using a rat model. Rats were randomly assigned to four groups: control, doxorubicin (20 mg/kg, intraperitoneal, i.p.), doxorubicin plus 100 mg/kg of geraniol, and doxorubicin plus 200 mg/kg of geraniol. A single doxorubicin injection triggered kidney impairment, as evidenced by the altered serum creatinine, blood urea nitrogen, and albumin values; it also caused histological changes in the kidney architecture. Additionally, doxorubicin enhanced lipid peroxidation while lowering reduced glutathione, catalase activity, and the expression of glutathione peroxidase and superoxide dismutase. Interestingly, pre-treatment with geraniol rescued doxorubicin-induced alterations in kidney antioxidant parameters, enzymatic activity, and the expression of inflammatory and apoptosis-mediating gene and proteins. Moreover, prophylactic treatment with geraniol preserved most kidney histological characteristics in a dose-dependent manner. These findings support that geraniol could protect against doxorubicin-mediated kidney dysfunction. However, further research is needed to clarify the mechanisms of geraniol’s protective effects against doxorubicin-mediated kidney dysfunction.

A next-generation probiotic: Akkermansia muciniphila ameliorates chronic stress-induced depressive-like behavior in mice by regulating gut microbiota and metabolites

Major depressive disorder (MDD) is a neurasthenic disease, which is the second-largest burden of disease globally. Increasing studies have revealed that depression is associated with abnormalities in gut microbiota and metabolites. Several species of bacteria have been classified as psychobiotics, which confer mental health benefits through interactions with commensal gut microbiota. Therefore, it is essential to identify new psychobiotics and elucidate their mechanisms in the treatment of depression. This study aims to evaluate the antidepressant effect of Akkermansia muciniphila (AKK) in a mouse model of depression induced by chronic restraint stress (CRS). C57BL/6 male mice were divided into three groups: mice subjected to CRS, mice not subjected to CRS, and mice treated with AKK for 3 weeks. Behavioral tests were performed, and hormone, neurotransmitter, and brain-derived neurotrophic factor (BDNF) levels were measured. Cecal microbiota was analyzed using 16S rRNA gene sequencing, and serum metabolites were detected using untargeted metabolomics. In addition, correlations between altered gut microbiota and metabolites with significant variations in serum associated with AKK ameliorating depression were analyzed using Pearson's correlation coefficient. The results revealed that AKK significantly ameliorated depressive-like behavior and restored abnormal variations in depression-related molecular (corticosterone, dopamine, and BDNF). Moreover, AKK altered chronic stress-induced gut microbial abnormalities. Untargeted metabolomics analysis revealed 23 potential biomarkers in serum that could be associated with the mechanisms underlying CRS-induced depression and the therapeutic effects of AKK. Pearson's correlation coefficient analysis revealed that AKK predominantly upregulated β-alanyl-3-methyl-L-histidine and edaravone to relieve depression. Furthermore, β-alanyl-3-methyl-L-histidine and edaravone exhibited the antidepressant phenotype in mice subjected to CRS. In conclusion, the study demonstrated that AKK ameliorates chronic stress-induced depressive symptoms in mice by regulating gut microbiota and metabolites. KEY POINTS: • AKK reduces depressive-like behaviors induced by chronic stress. • AKK regulates the gut microbial structure and metabolomics of serum under the chronic stress. • Antidepressant effect of AKK correlates with the increase of β-alanyl-3-methyl-l-histidine and edaravone.

Geraniol Averts Methotrexate-Induced Acute Kidney Injury via Keap1/Nrf2/HO-1 and MAPK/NF-κB Pathways

Objectives: Geraniol, a natural monoterpene, is an essential oil component of many plants. Methotrexate is an anti-metabolite drug, used for cancer and autoimmune conditions; however, clinical uses of methotrexate are limited by its concomitant renal injury. This study investigated the efficacy of geraniol to prevent methotrexate-induced acute kidney injury and via scrutinizing the Keap1/Nrf2/HO-1, P38MAPK/NF-κB and Bax/Bcl2/caspase-3 and -9 pathways. Methods: Male Wister rats were allocated into five groups: control, geraniol (orally), methotrexate (IP), methotrexate and geraniol (100 and 200 mg/kg). Results: Geraniol effectively reduced the serum levels of creatinine, urea and Kim-1 with an increase in the serum level of albumin when compared to the methotrexate-treated group. Geraniol reduced Keap1, escalated Nrf2 and HO-1, enhanced the antioxidant parameters GSH, SOD, CAT and GSHPx and reduced MDA and NO. Geraniol decreased renal P38 MAPK and NF-κB and ameliorated the inflammatory mediators TNF-α, IL-1β, IL-6 and IL-10. Geraniol negatively regulated the apoptotic mediators Bax and caspase-3 and -9 and increased Bcl2. All the biochemical findings were supported by the alleviation of histopathological changes in kidney tissues. Conclusion: The current findings support that co-administration of geraniol with methotrexate may attenuate methotrexate-induced acute kidney injury.

Targeting NLRP3 Inflammasome in Translational Treatment of Nervous System Diseases: An Update

Neuroinflammatory response is the immune response mechanism of the innate immune system of the central nervous system. Both primary and secondary injury can activate neuroinflammatory response. Among them, the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome plays a key role in the inflammatory response of the central system. Inflammasome is a type of pattern recognition receptor, a cytoplasmic polyprotein complex composed of members of the Nod-like receptor (NLR) family and members of the pyrin and HIN domain (PYHIN) family, which can be affected by a variety of pathogen-related molecular patterns or damage-related molecular patterns are activated. As one of the research hotspots in the field of medical research in recent years, there are increasing researches on immune function abnormalities in the onset of neurological diseases such as depression, AD, ischemic brain injury and cerebral infarction, the NLRP3 inflammasome causes the activated caspase-1 to cleave pre-interleukin-1β and pre-interleukin-18 into mature interleukin-1β and interleukin-18, in turn, a large number of inflammatory factors are produced, which participate in the occurrence and development of the above-mentioned diseases. Targeted inhibition of the activation of inflammasomes can reduce the inflammatory response, promote the survival of nerve cells, and achieve neuroprotective effects. This article reviews NLRP3 inflammasome's role in neurological diseases and related regulatory mechanisms, which providing references for future research in this field.

Research Progress on Natural Compounds Exerting an Antidepressant Effect through Anti-inflammatory

Depression is a common mental illness that belongs to the category of emotional disorders that causes serious damage to the health and life of patients, while inflammation is considered to be one of the important factors that causes depression. In this case, it might be important to explore the possible therapeutic approach by using natural compounds exerting an anti-inflammatory and antidepressant effect, which it filed has not been systematically reviewed recently. Hence, this review aims to systematically sort the literature related to the mechanism of exerting an antidepressant effect through anti-inflammatory actions, and to summarize the related natural products in the past 20 years, in terms of a number of inflammatory related pathways (i.e., the protein kinase B (Akt) pathway, monoamine neurotransmitters (5-hydroxytryptamine and norepinephrine) (5-HT and NE), the nod-like receptor protein-3 (NLRP3) inflammasome, proinflammatory cytokines, neurotrophins, or cytokine-signaling pathways), which might provide a useful reference for the potential treatment of depression.

6-Gingerol, a Major Constituent of Zingiber officinale Rhizoma, Exerts Anticonvulsant Activity in the Pentylenetetrazole-Induced Seizure Model in Larval Zebrafish

Zingiber officinale is one of the most frequently used medicinal herbs in Asia. Using rodent seizure models, it was previously shown that Zingiber officinale hydroethanolic extract exerts antiseizure activity, but the active constituents responsible for this effect have not been determined. In this paper, we demonstrated that Zingiber officinale methanolic extract exerts anticonvulsant activity in the pentylenetetrazole (PTZ)-induced hyperlocomotion assay in larval zebrafish. Next, we isolated 6-gingerol (6-GIN)-a major constituent of Zingiber officinale rhizoma. We observed that 6-GIN exerted potent dose-dependent anticonvulsant activity in the PTZ-induced hyperlocomotion seizure assay in zebrafish, which was confirmed electroencephalographically. To obtain further insight into the molecular mechanisms of 6-GIN antiseizure activity, we assessed the concentration of two neurotransmitters in zebrafish, i.e., inhibitory γ-aminobutyric acid (GABA) and excitatory glutamic acid (GLU), and their ratio after exposure to acute PTZ dose. Here, 6-GIN decreased GLU level and reduced the GLU/GABA ratio in PTZ-treated fish compared with only PTZ-bathed fish. This activity was associated with the decrease in grin2b, but not gabra1a, grin1a, gria1a, gria2a, and gria3b expression in PTZ-treated fish. Molecular docking to the human NR2B-containing N-methyl-D-aspartate (NMDA) receptor suggests that 6-GIN might act as an inhibitor and interact with the amino terminal domain, the glutamate-binding site, as well as within the ion channel of the NR2B-containing NMDA receptor. In summary, our study reveals, for the first time, the anticonvulsant activity of 6-GIN. We suggest that this effect might at least be partially mediated by restoring the balance between GABA and GLU in the epileptic brain; however, more studies are needed to prove our hypothesis.

Anxiolytic and antidepressant-like effects of essential oil from the fruits of Piper nigrum Linn. (Black pepper) in mice: involvement of serotonergic but not GABAergic transmission system

In this study, the anxiolytic activity of Piper nigrum essential oil (PNEO) was evaluated in the elevated plus maze (EPM) and the antidepressant-like effect was evaluated through tail suspension test (TST) in mice. Flumazenil, a competitive inhibitor of GABA_A receptor in the benzodiazepine site and WAY-100635 maleate salt, a 5-HT_1A receptor antagonist were used to find out the possible mechanism(s) of action of PNEO. To exclude the false-positive results due to the enhancement of the locomotor activity, the animals were submitted to open field test (OFT). We also measured monoamines levels of the mice brain after acute PNEO treatment. The data obtained from the study suggest that the anxiolytics and antidepressant-like effect of PNEO have observed in EPM and TST respectively in a dose-dependent manner after oral acute and repetitive treatment. WAY-100635, but not flumazenil was able to reverse the effect of PNEO in EPM and TST both, indicating the possible involvement of 5-HT_1A receptor. The neurochemical analysis showed no alteration in monoamine levels in mice brains. Furthermore, no locomotor impairment or sign of toxicity or changes in body weight or abnormalities in the biochemical parameters, except for a significant decrease in total cholesterol level was observed after treatment with PNEO. The findings suggest that Piper nigrum EO possesses a dual anxiolytic and antidepressant-like effect through the possible involvement of serotonergic transmission.

Engineering Escherichia coli for production of geraniol by systematic synthetic biology approaches and laboratory-evolved fusion tags

Geraniol is a valuable monoterpene extensively used in the fragrance, food, and cosmetic industries. Increasing environmental concerns and supply gaps have motivated efforts to advance the microbial production of geraniol from renewable feedstocks. In this study, we first constructed a platform geraniol Escherichia coli strain by bioprospecting the key enzymes geranyl diphosphate synthase (GPPS) and geraniol synthase (GES) and selection of a host cell background. This strategy led to a 46.4-fold increase in geraniol titer to 964.3 mg/L. We propose that the expression level of eukaryotic GES can be further optimized through fusion tag evolution engineering. To this end, we manipulated GES to maximize flux towards the targeted product geraniol from precursor geranyl diphosphate (GPP) via the utilization of fusion tags. Additionally, we developed a high-throughput screening system to monitor fusion tag variants. This common plug-and-play toolbox proved to be a robust approach for systematic modulation of protein expression and can be used to tune biosynthetic metabolic pathways. Finally, by combining a modified E1* fusion tag, we achieved 2124.1 mg/L of geraniol in shake flask cultures, which reached 27.2% of the maximum theoretical yield and was the highest titer ever reported. We propose that this strategy has set a good reference for enhancing a broader range of terpenoid production in microbial cell factories, which might open new possibilities for the bio-production of other valuable chemicals.

Oridonin ameliorates insulin resistance partially through inhibition of inflammatory response in rats subjected to chronic unpredictable mild stress

BACKGROUND

Oridonin (Ori) has multiple biological properties, especially anti-inflammatory. However, its effects on chronic unpredictable mild stress (CUMS)-induced insulin resistance are still unclear. In this study, we explored the regulatory role of Ori in CUMS-triggered insulin resistance, and the underlying molecular mechanisms; Methods: SD rats were subjected to CUMS for 4 weeks, some of which were injected with Ori or fluoxetine (FLX) in durations of CUMS. After CUMS procedure, the behavioral and metabolic tests were performed. Elisa, immunofluorescence and western blotting were used to determine the inflammatory response and NLRP3 inflammasome activation. We investigated the interaction between NLRP3 and NEK7 using immunoprecipitation. Finally, we detected the proinflammatory cytokines in Lipopolysaccharide (LPS)-activated RAW264.7 cells treated with Ori; RESULTS: In this study, we found that chronic stress resulted in depressive-like behavior comorbid with insulin resistance. Ori was discovered to ameliorate insulin resistance as well as insulin signaling disturbance in the hippocampus. In addition, CUMS caused the infiltration of macrophages into the islets. And IL-1β, IL-18 and caspase-1 were elevated in pancreases of CUMS rats, which could also be reversed by Ori treatment via reducing the interaction between NLRP3 and NEK7. Furthermore, Ori dose-dependently inhibited the levels of IL-1β and IL-18 in LPS-activated RAW264.7 cells; CONCLUSIONS: All these results supported our hypothesis that Ori possesses potent anti-insulin resistant actions, which is partially correlated with inhibiting infiltration of macrophages into the islets and NLRP3 activation induced by CUMS. Therefore, our results highlighted the protective role of Ori against CUMS-elicited insulin resistance.

Use of medicinal plants for headache, and their potential implication in medication-overuse headache: Evidence from a population-based study in Nepal

Background

In Nepal, traditional treatment using medicinal plants is popular. Whereas medication-overuse headache is, by definition, caused by excessive use of acute headache medication, we hypothesized that medicinal plants, being pharmacologically active, were as likely a cause.

Methods

We used data from a cross-sectional, nationwide population-based study, which enquired into headache and use of medicinal plants and allopathic medications. We searched the literature for pharmacodynamic actions of the medicinal plants.

Results

Of 2100 participants, 1794 (85.4%) reported headache in the preceding year; 161 (7.7%) reported headache on ≥15 days/month, of whom 28 (17.4%) had used medicinal plants and 117 (72.7%) allopathic medication(s). Of 46 with probable medication-overuse headache, 87.0% (40/46) were using allopathic medication(s) and 13.0% (6/46) medicinal plants, a ratio of 6.7:1, higher than the overall ratio among those with headache of 4.9:1 (912/185). Of 60 plant species identified, 49 were pharmacodynamically active on the central nervous system, with various effects of likely relevance in medication-overuse headache causation.

Conclusions

MPs are potentially a cause of medication-overuse headache, and not to be seen as innocent in this regard. Numbers presumptively affected in Nepal are low but not negligible. This pioneering project provides a starting point for further research to provide needed guidance on use of medicinal plants for headache.

Monoterpenes as a perspective for the treatment of seizures: A Systematic Review

BACKGROUND

Epilepsy affects more than 65 million people worldwide. Treatment for epileptic seizures is ineffective and has many adverse effects. For this reason, the search for new therapeutic options capable of filling these limitations is necessary.

HYPOTHESIS/PURPOSE

In this sense, natural products, such as monoterpenes, have been indicated as a new option to control neurological disorders such as epilepsy.

STUDY DESIGN

Therefore, the objective of this study was to review the monoterpenes that have anticonvulsive activity in animal models.

METHODS

The searches were performed in the PubMed, Web of Science and Scopus databases in September, 2020 and compiled studies using monoterpenes as an alternative to seizure. Two independent reviewers performed the study selection, data extraction and methodological quality assessment using the Syrcle tool.

RESULTS

51 articles that described the anticonvulsant activity of 35 monoterpenes were selected with action on the main pharmacological target, including GABAA receptors, glutamate, calcium channels, sodium and potassium. In addition, these compounds are capable of reducing neuronal inflammation and oxidative stress caused by seizure.

CONCLUSION

These compounds stand out as a promising alternative for acting through different pharmacological mechanisms, which may not only reduce seizure, but also promote neuroprotective effect by reducing toxicity in brain regions. However, further studies are needed to determine the mechanism of action and safety assessment of these compounds.

Natural volatile oils derived from herbal medicines: A promising therapy way for treating depressive disorder

Depression is a common global mental disorder that seriously harms human physical and mental health. With the development of society, the increase of pressure and the role of various other factors make the incidence of depression increase year by year. However, there is a lack of drugs that have a fast onset, significant effects, and few side effects. Some volatile oils from traditional natural herbal medicines are usually used to relieve depression and calm emotions, such as Lavender essential oil and Acorus tatarinowii essential oil. It was reported that these volatile oils, are easy to enter the brain through the blood-brain barrier and have good antidepressant effects with little toxicity and side effects. In this review, we summarized the classification of depression, and listed the history of using volatile oils to fight depression in some countries. Importantly, we summarized the anti-depressant natural volatile oils and their monomers from herbal medicine, discussed the anti-depressive mechanisms of the volatile oils from natural medicine. The volatile oils of natural medicine and antidepressant drugs were compared and analyzed, and the application of volatile oils was explained from the clinical use and administration routes. This review would be helpful for the development of potential anti-depressant medicine and provide new alternative treatments for depressive disorders.

Increasing γ-Aminobutyric Acid Content in Vegetable Soybeans via High-Pressure Processing and Efficacy of Their Antidepressant-Like Activity in Mice

This study applied high-pressure processing (HPP) technology to enrich the gamma aminobutyric acid (GABA) content in vegetable soybeans and evaluated its antidepressant efficacy on mice, with depression induced by the unpredictable chronic mild stress (UCMS) model. The optimal conditions for HPP, storage time, and storage temperature, as well as antidepressant-like effects of vegetable soybeans, were evaluated and discussed. HPP could effectively and significantly increase GABA content in soybean, with optimum conditions at 200 MPa. The GABA content in the whole vegetable soybean was 436.05 mg/100 g. In mice animal tests, the tail suspension test (TST) showed that the immobility time of the GABA group was significantly shorter than that of the control group. The total travel distance in the open field test (OFT) showed that depressed mice fed with the GABA feed exhibited exploratory behavior. The GABA group showed a significantly higher degree of sucrose preference than the control group. Both results indicate that the GABA feed could effectively alleviate depressive symptomatology. Regarding biochemical parameters, the fecal and serum corticosterone (CORT) levels in the control group increased to 104.86 pg/mg after the onset of depression. In contrast, the fecal CORT level in the GABA group was significantly reduced to 23.98 pg/mg and was comparable to that in the control group (33.38 pg/mg). Reduced serum CORT level in the GABA group suggests an improvement in depressive symptomatology. The serotonin concentration was maintained in the GABA group after the induction of depression, suggesting its preventive activity. The HPP GABA-enriched soybeans exerted modulatory effects on the behaviors of depressed mice and displayed a potential for commercialization.

Stress-induced blood brain barrier disruption: Molecular mechanisms and signaling pathways

Stress is a nonspecific response to a threat or noxious stimuli with resultant damaging consequences. Stress is believed to be an underlying process that can trigger central nervous system disorders such as depression, anxiety, and post-traumatic stress disorder. Though the pathophysiological basis is not completely understood, data have consistently shown a pivotal role of inflammatory mediators and hypothalamo-pituitary-adrenal (HPA) axis activation in stress induced disorders. Indeed emerging experimental evidences indicate a concurrent activation of inflammatory signaling pathways and not only the HPA axis, but also, peripheral and central renin-angiotensin system (RAS). Furthermore, recent experimental data indicate that the HPA and RAS are coupled to the signaling of a range of central neuro-transmitter, -mediator and -peptide molecules that are also regulated, at least in part, by inflammatory signaling cascades and vice versa. More recently, experimental evidences suggest a critical role of stress in disruption of the blood brain barrier (BBB), a neurovascular unit that regulates the movement of substances and blood-borne immune cells into the brain parenchyma, and prevents peripheral injury to the brain substance. However, the mechanisms underlying stress-induced BBB disruption are not exactly known. In this review, we summarize studies conducted on the effects of stress on the BBB and integrate recent data that suggest possible molecular mechanisms and signaling pathways underlying stress-induced BBB disruption. Key molecular targets and pharmacological candidates for treatment of stress and related illnesses are also summarized.

The Effects of Essential Oils and Terpenes in Relation to Their Routes of Intake and Application

Essential oils have been used in multiple ways, i.e., inhaling, topically applying on the skin, and drinking. Thus, there are three major routes of intake or application involved: the olfactory system, the skin, and the gastro-intestinal system. Understanding these routes is important for clarifying the mechanisms of action of essential oils. Here we summarize the three systems involved, and the effects of essential oils and their constituents at the cellular and systems level. Many factors affect the rate of uptake of each chemical constituent included in essential oils. It is important to determine how much of each constituent is included in an essential oil and to use single chemical compounds to precisely test their effects. Studies have shown synergistic influences of the constituents, which affect the mechanisms of action of the essential oil constituents. For the skin and digestive system, the chemical components of essential oils can directly activate gamma aminobutyric acid (GABA) receptors and transient receptor potential channels (TRP) channels, whereas in the olfactory system, chemical components activate olfactory receptors. Here, GABA receptors and TRP channels could play a role, mostly when the signals are transferred to the olfactory bulb and the brain.

Novel Intranasal Drug Delivery: Geraniol Charged Polymeric Mixed Micelles for Targeting Cerebral Insult as a Result of Ischaemia/Reperfusion

Brain damage caused by cerebral ischaemia/reperfusion (I/R) can lead to handicapping. So, the present study aims to evaluate the prophylactic and therapeutic effects of geraniol in the form of intranasal polymeric mixed micelle (PMM) on the central nervous system in cerebral ischaemia/reperfusion (I/R) injury. A 3² factorial design was used to prepare and optimize geraniol PMM to investigate polymer and stabilizer different concentrations on particle size (PS) and percent entrapment efficiency (%EE). F3 possessing the highest desirability value (0.96), with a PS value of 32.46  ±  0.64 nm, EE of 97.85  ±  1.90%, and release efficiency of 59.66  ±  0.64%, was selected for further pharmacological and histopathological studies. In the prophylactic study, animals were classified into a sham-operated group, a positive control group for which I/R was done without treatment, and treated groups that received vehicle (plain micelles), geraniol oil, and geraniol micelles intranasally before and after I/R. In the therapeutic study, treated rats received geraniol oil and micelles after I/R. Evaluation of the effect of geraniol on behavior was done by activity cage and rotarod and the analgesic effect tested by hot plate. Anti-inflammatory activity was assessed by measuring interleukin β6, cyclooxygenase-2, hydrogen peroxide, and inducible nitric oxide synthase. Histopathogical examination of cerebral cortices was also done to confirm the results of a biochemical assay. Geraniol nanostructured polymeric mixed micelles showed an enhanced neuro-protective effect compared to geraniol oil, confirming that PMM via intranasal route could be an efficient approach for delivering geraniol directly to the brain through crossing the blood-brain barrier.

Nutritional psychoneuroimmunology: Is the inflammasome a critical convergence point for stress and nutritional dysregulation?

Psychoneuroimmunology (PNI) aims to elucidate mechanisms by which the immune system can influence behavior. Given the complexity of the brain, studies using inbred rodents have shed critical insight into the presumed vagaries of the human condition. This is particularly true for stress modeling where adverse stimuli, conditions and/or interactions elicit patterned behavioral reactions that can translate across species. As example, sickness behaviors are as easily recognized in mice as they are in humans, and a family pet. Recently, nutrition has gained prominence as a regulator of brain function. Once perceived as mostly a peripheral player, except when manifest at extremes like starvation or gluttony, nutritional and/or metabolic stress is now recognized as a worrisome contributor to poor mental health especially in those who suffer from food insecurity or overnutrition. In this review, we will explore emerging areas of rodent research that demonstrate the impact of nutritional status on the stressed brain. Our overall goal is to implicate inflammasome activation as a critical convergence point for stress and nutritional dysregulation. In doing so, we will present results from studies focused on macronutrient, micronutrient and dietary bioactives so as to encourage innovative investigation into the emerging field of nutritional PNI.

β-asarone relieves chronic unpredictable mild stress induced depression by regulating the extracellular signal-regulated kinase signaling pathway

The present study aimed to investigate the effect of β-asarone treatment in a rat model of depression induced by chronic unpredictable mild stress (CUMS) and to further explore the underlying molecular mechanisms. A rat model of depression was established by subjecting rat to CUMS and treated with various concentrations of β-asarone (12.5, 25 and 50 mg/kg/day) and fluoxetine (20 mg/kg/day). Next, behavioral tests, including an open field, sucrose preference and forced swimming tests, were performed. In addition, the apoptosis of hippocampal neuronal cells was determined by flow cytometry, gene expression levels were detected by reverse transcription-quantitative polymerase chain reaction and protein levels were determined by western blot assay. The results revealed that β-asarone significantly mitigated CUMS-induced depression-like behavior, evidenced by the increased sucrose intake, crossing and rearing numbers, and decreased immobility time in the forced swimming test. Furthermore, β-asarone significantly decreased the apoptosis rate of hippocampal neuronal cells in rats subjected to CUMS. β-asarone was also found to enhance CREB, BDNF, Trk-B and Bcl-2 levels, and reduce Bad level in the hippocampus of CUMS-treated rats. In addition, the activation of extracellular signal-regulated kinase pathway inhibited by CUMS was promoted by β-asarone treatment. In conclusion, the present study findings indicated the antidepressant-like effects of β-asarone on CUMS-induced depression in rats.

Oral supplementation with geranium oil or anise oil ameliorates depressed rat-related symptoms through oils antioxidant effects

Background Depression is a psychiatric disease condition and the chronic mild stress (CMS) model is a well-known and valuable animal model of depression. Geranium oil and anise oil were chosen for such a study. The aim of this research was to establish the geranium oil and anise oil effect to ameliorate CMS-related symptoms. Methods This research included 80 male albino rats each group of 10 rats and the animals were divided into two major groups: normal and CMS. The normal group was subdivided into four (control, geranium oil, anise oil and venlafaxine drug) subgroups treated orally with saline, geranium oil, anise oil and venlafaxine drug, respectively, for 4 weeks. The CMS group was subdivided into four (CMS without any treatment, CMS + geranium oil, CMS + anise oil and CMS + venlafaxine drug) subgroups treated orally with geranium oil, anise oil and venlafaxine drug, respectively, for 4 weeks. Results The sucrose consumption in sucrose preference test, the distance traveled test and center square entries test were decreased, while center square duration test, immobility time in tail suspension test and floating time in forced swimming test were increased in CMS. The superoxide dismutase, glutathione peroxidase, glutathione-S-transferase, glutathione reductase and catalase levels decreased but malondialdehyde and nitric oxide levels increased in brain cerebral cortex and hippocampus areas in CMS. The oral intake of geranium oil and anise oil pushes all these parameters to approach the control levels. These results were supported by histopathological investigations of both brain cerebral cortex and hippocampus tissues. Conclusions Geranium oil and anise oil ameliorate CMS-related symptoms and this effect were related to the antioxidant effects of oils.

Ameliorative effect of Magnesium Isoglycyrrhizinate on hepatic encephalopathy by Epirubicin

BACKGROUND

The purpose of the present study was to evaluate the protective effect of Magnesium Isoglycyrrhizinate (MI) on Epirubicin (EPI)-induced hepatic encephalopathy (HE) and explore its underlying mechanism.

METHODS

Mice were divided randomly into groups for treatments as follows: control group, EPI group (Model group), EPI + MI (25, 50 mg/kg) group. Morris water maze test were conducted to evaluate the spatial learning and memory ability. The serum and hippocampus levels of oxidative stress or inflammation were uncovered with the detection of superoxide dismutase (SOD), malondialdehyde (MDA), and pro-inflammatory cytokines (IL-1β, IL-6, TNF-α).

RESULTS

As a result, treatment with MI effectively ameliorated the EPI-induced decline in the ability of spatial learning and memory. MI also significantly relieved the severity of oxidative stress or inflammation in serum and hippocampus, which was accompanied with regulating liver functional parameters. Western blot data demonstrated that administration of MI could regulate the redox-related expressions of Txnip, Trx, Nrf2, HO-1, p-IκB-α, p-NF-κB, Caspase-3, Caspase-9, Bax and Bcl-2 in EPI-stimulated hepatic encephalopathy (HE). And the potency of MI treatments on Nrf2, NF-κB expression was also confirmed with immunohistochemical analysis.

CONCLUSIONS

Taken together, the protective effect of Magnesium Isoglycyrrhizinate on EPI-induced hepatic encephalopathy might be mediated via the Txnip/Nrf2/NF-κB signaling pathway.