Antidepressant-like effect of lemon essential oil is through a modulation in the levels of norepinephrine, dopamine, and serotonin in mice: Use of the tail suspension test

Intranasal administration of the essential oil from Perillae Folium ameliorates social defeat stress-induced behavioral impairments in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Perillae Folium, the leaves and twigs of Perilla frutescens (L.) Britton, has been included in many traditional Chinese medicine herbal formulas to treat depression. However, the precise antidepressant mechanism of the essential oil from Perillae Folium (PFEO) has not been fully investigated.

AIM OF THE STUDY

To assess the effects and potential mechanisms of PFEO on depression using animal models and network pharmacology analysis.

MATERIALS AND METHODS

PFEO was intranasally administered to a mouse model of social defeat stress (SDS). The antidepressant effects of PFEO on SDS-induced mice were evaluated using behavioral tests. Enzyme-linked immunosorbent assay (ELISA) and western blot were performed to measure the levels of depression-related biomarkers in the hippocampus and serum of the mice. The chemical compounds of PFEO were determined using gas chromatography-mass spectrometry (GC-MS). Network pharmacology and molecular docking analyses were conducted to investigate the potential bioactive components of PFEO and the mechanisms underlying the antidepressant effects. To validate the mechanisms of the bioactive compounds, in vitro models using PC12 and BV2 cells were established and the blood-brain barrier (BBB) permeability was evaluated.

RESULTS

The intranasal administration of PFEO suppressed SDS-induced depression in mice by increasing the time spent in the social zone and the social interactions in the social interaction test and by decreasing the immobility time in the tail suspension and forced swimming tests. Moreover, the PFEO treatment reduced the SDS-induced anxiety-like behavior, as inferred from the increased activity in the central zone observed in the open field test and in the open arms observed in the elevated plus maze test. PFEO administration recovered the SDS-induced decrease in the levels of 5-HT, NE, gamma-aminobutyric acid (GABA), and p-ERK in the hippocampus of mice. Furthermore, the increased serum corticosterone level was also attenuated by the PFEO treatment. A total of 21 volatile compounds were detected in PFEO using GC-MS, among which elemicin (15.52%), apiol (15.16%), and perillaldehyde (12.79%) were the most abundant ones. The PFEO compounds targeted 32 depression-associated genes, which were mainly related to neural cells and neurotransmission pathways. Molecular docking indicated good binding affinities between the bioactive components of PFEO (apiol, β-caryophyllene, elemicin, and myristicin) and the key targets, including ACHE, IL1B, IL6, MAOB, SLC6A2, SLC6A3, SLC6A4, and tumor necrosis factor. Among the four compounds, β-caryophyllene, elemicin, and myristicin were more effective in reducing neurotoxicity and neuroinflammation. Elemicin showed the highest BBB permeability rate.

CONCLUSIONS

This study shows the antidepressant activities of PFEO in an SDS-induced mouse model and suggests its potential mechanisms of action: regulation of the corticosterone levels, hippocampal neurotransmitters, and ERK signaling. Apiol, β-caryophyllene, elemicin, and myristicin may be the main contributors to the observed effects induced by PFEO. Further studies are needed to fully elucidate the underlying mechanisms and the main PFEO bioactive components.

Microbial bionic nano-aromatic drugs for prevention of depression induced by chronic stress

Depression is a mood disorder mainly clinically characterized by significant and persistent low spirits. Chronic stress is the leading cause of depression. However, traditional medicine has severe side effects in treating depression, ineffective treatment, and easy recurrence. Therefore, it is of great significance to prevent depression in the environment of chronic stress. In this study, aromatherapy was used for the prevention of depression. To solve the defects of intense volatility and inconvenience in using essential oils, we designed bionic nano-aromatic drugs and adhered them to the wallpaper. Inspired by the moldy wallpaper, we successively prepared the morphology-bionic nano-aromatic drugs, the function-bionic nano-aromatic drugs, and the bionic plus nano-aromatic drugs by referring to the morphology of microorganisms and substances in bacterial biofilms. Bionic nano-aromatic drugs remarkably promoted their adhesion on wallpaper. Molecular dynamics simulation explored its molecular mechanism. The essential oils, which were slowly released from the bionic nano-aromatic drugs, showed excellent biosecurity and depression prevention. These sustainedly released essential oils could significantly increase monoamine neurotransmitters in the brain under a chronic stress environment and had excellent neuroprotection. Besides, the bionic nano-aromatic drugs with simple preparation process and low cost had excellent application potential.

Olfactory Cues to Reduce Retrograde Interference During the Simultaneous Learning of Conflicting Motor Tasks

We investigated the ability of humans to adapt to a novel environment by kinematic transformation. This adaptation was studied via behavioural experiments using a robotic manipulandum – a system designed to arbitrarily generate virtual force fields against a human hand and subsequently record the hand’s trajectory. By repeating motor tasks, this study’s participants gradually learned to move correctly under a newly experienced force field, such as rotating in a clockwise direction. However, each participant’s motor memory was destroyed if he/she experienced an opposing force field (e.g., in a counterclockwise direction) immediately after learning the initial movement, which is known as retrograde interference. In some previous studies, it has been considered that by presenting sensory cues to highlight the difference in two opposing force fields, participants can learn both force fields independently without interference. In this study, we investigated the functionality of olfactory cues – specifically lemon and lavender odors – in reducing retrograde interference. Forty-five university students participated in an experiment using a robotic manipulandum. Our results have shown that the presence of lemon odor reduces the destruction of motor memory, while that of lavender did not, suggesting that odors can enhance simultaneous motor learning but the effect depends on the type of odor used.

Linalool as a Therapeutic and Medicinal Tool in Depression Treatment: A Review

Depression is a prevalent disease worldwide, limiting psychosocial functioning and thequality of life. Linalool is the main constituent of some essential oils from aromatic plants, representing about 70% of these volatile concentrates. Evidence of the linalool activity on the central nervous system, mainly acting as an antidepressant agent, is increasingly abundant. This review aimed to extend the knowledge of linalool's antidepressant action mechanisms, which is fundamental for future research, intending to highlight this natural compound as a new antidepressant phytomedication. A critical analysis is proposed here with probable hypotheses of the synergic mechanisms that support the evidence of antidepressant effects of the linalool. The literature search has been conducted in databases for published scientific articles before December 2020, using relevant keywords. Several pieces of evidence point to the anticonvulsant, sedative, and anxiolytic actions. In addition to these activities, other studies have revealed that linalool acts on the monoaminergic and neuroendocrine systems, inflammatory process, oxidative stress, and neurotrophic factors, such as BDNF, resulting in considerable advances in the knowledge of the etiology of depression. In this context, linalool emerges as a promising bioactive compound in the therapeutic arsenal, capable of interacting with numerous pathophysiological factors and acting on several targets. This review claims to contribute to future studies, highlighting the gaps in the linalool knowledge, such as its kinetics, doses, routes of administration, and multiple targets of interaction, to clarify its antidepressant activity.

Anxiolytic effects of essential oils may involve anti-oxidant regulation of the pro-oxidant effects of ascorbate in the brain

Essential oils (EOs) absorbed via inhalation are consistently reported to produce anxiolytic effects. The underlying neurochemical mechanisms, however, are not well understood. High concentrations of ascorbate in the human brain (~10 mM in neurons) implicates this compound as a key signaling molecule and regulator of oxidative stress. In this study, we demonstrate the significant in vitro capacity of ascorbate to produce H₂O₂ in the presence of oxygen at physiological pH values, peaking at ~400 μM for ascorbate levels of 1.0 mg/mL (5.6 mM). In comparison, individual EOs and selected neurotransmitters at similar concentrations produced <100 μM H₂O₂. Systematic studies with binary and ternary mixtures containing ascorbate indicated that EOs and neurotransmitters could variably enhance (pro-oxidant, POX) or suppress (anti-oxidant, AOX) the production of H₂O₂ versus the ascorbate control, depending on the concentration ratios of the components in the mixture. Moreover, the AOX/POX chemistry observed with binary mixtures did not necessarily predict effects with ternary mixtures, where the POX ascorbate chemistry tended to dominate. A model is proposed to account for the ability of compounds with electron-donating capacity to catalytically regenerate ascorbate from intermediate oxidized forms of ascorbate, thus driving H₂O₂ production and exerting a net POX effect; whilst compounds that irreversibly reacted with oxidized forms of ascorbate suppressed the production of H₂O₂ and produced an overall AOX effect. Since the anxiolytic effects of different EOs, including extracts of Lavendula angustifolia (lavender) and Salvia rosmarinus (rosemary), were associated with AOX regulation of H₂O₂ production by ascorbate, it can be concluded that these anxiolytic effects are potentially related to the AOX properties of EOs. In contrast, EOs driving POX effects (eg, Junipenus communis (Juniper) berry EO) are proposed to be more useful for their potential anti-microbial or cancer cytotoxic applications.

Pharmacogenetic-based management of depression: Role of traditional Persian medicine

Depression is one of the most common mental disorders worldwide. The genetic factors are linked to depression and anti-depressant outcomes. Traditional Persian medicine (TPM) manuscripts have provided various anti-depressant remedies, which may be useful in depression management. This review has studied the bioactive compounds, underlying mechanisms, and treatment outcomes of the medicinal plants traditionally mentioned effective for depression from "The storehouse of medicament" (a famous pharmacopeia of TPM) to merge those with the novel genetics science and serve new scope in depression prevention and management. This review paper has been conducted in two sections: (1) Collecting medicinal plants and their bioactive components from "The storehouse of medicament," "Physician's Desk Reference (PDR) for Herbal Medicines," and "Google scholar" database. (2) The critical key factors and genes in depression pathophysiology, prevention, and treatment were clarified. Subsequently, the association between bioactive components' underlying mechanism and depression treatment outcomes via considering polymorphisms in related genes was derived. Taken together, α-Mangostin, β-carotene, β-pinene, apigenin, caffeic acid, catechin, chlorogenic acid, citral, ellagic acid, esculetin, ferulic acid, gallic acid, gentiopicroside, hyperoside, kaempferol, limonene, linalool, lycopene, naringin, protocatechuic acid, quercetin, resveratrol, rosmarinic acid, and umbelliferone are suitable for future pharmacogenetics-based studies in the management of depression.

Behavioural and biochemical indications of the antidepressant activities of essential oils from Monodora myristica (Gaertn) seed and Xylopia aethiopica (Dunal) fruit in rats

Monodora myristica and Xylopia aethiopica are two underutilised spices that are hypothesized to be important in the management and treatment of certain stress-induced diseases such as depression. The present study was designed to test the anti-depressant effects of the essential oils of Monodora myristica (EOMM) and Xylopia aethiopica (EOXA) and the possible underlying mechanisms in a chronic unpredictable mild stress (CUMS) - induced depression in the rat. Forty-two male Wistar rats were assigned to seven groups (n = 6); group I received corn oil (p.o, unstressed control), group II (stressed control) administered corn oil, groups III-IV received EOMM (150 & 300 mg/kg, p.o), groups V – VI received EOXA (150 & 300 mg/kg, p.o) whereas group VII had fluoxetine (10 mg/kg, p.o in d/w). Corn oil served as the vehicle for the delivery of the essential oils and the doses were administered via gastric intubation to rat once daily for six consecutive weeks from the 2nd week. Open-field, tail suspension (TST), and forced swimming (FST) tests were used to evaluate the behavioural activity in addition to the biochemical parameters (catalase, superoxide dismutase, reduced glutathione, monoamine oxidase, corticosterone, protein carbonyl compound, malondialdehyde and nitric oxide). The result showed that the administration of EOMM (150 and 300 mg/kg b.wt.) and EOXA (150 and 300 mg/kg b.wt.) during CUMS significantly ameliorated these behavioural activities and some biochemical parameters in rats. EOMM and EOXA exhibited significant antidepressant-like effects in a rat model of CUMS. At treatment doses of especially 300 mg/kg b.wt, the antidepressant effects of EOMM and EOXA are comparable to a standard antidepressant drug, fluoxetine (Prozac ™). The EOXA especially at a dose of 300 mg/kg b.wt is more effective than EOMM even at 300 mg/kg dose level in ameliorating depression in stressed rats. In conclusion, the study revealed that both the EOXA and EOMM relieved depression-like states through the mitigation of oxidative stress with a reduction in serum Corticosterone (CORT) and brain Monoamine Oxidase-A (MAO-A) levels.

Detection of Orange Essential Oil, Isopropyl Myristate, and Benzyl Alcohol in Lemon Essential Oil by FTIR Spectroscopy Combined with Chemometrics

Essential oils are high-valued natural extracts that are involved in industries such as food, cosmetics, and pharmaceutics. The lemon essential oil (LEO) has high economic importance in the food and beverage industry because of its health-beneficial characteristics and desired flavor properties. LEO, similar to other natural extracts, is prone to being adulterated through economic motivations. Adulteration causes unfair competition between vendors, disruptions in national economies, and crucial risks for consumers worldwide. There is a need for cost-effective, rapid, reliable, robust, and eco-friendly analytical techniques to detect adulterants in essential oils. The current research developed chemometric models for the quantification of three adulterants (orange essential oil, benzyl alcohol, and isopropyl myristate) in cold-pressed LEOs by using hierarchical cluster analysis (HCA), principal component regression (PCR), and partial least squares regression (PLSR) based on FTIR spectra. The cold-pressed LEO was successfully distinguished from adulterants by robust HCA. PLSR and PCR showed high accuracy with high R² values (0.99-1) and low standard error of cross-validation (SECV) values (0.58 and 5.21) for cross-validation results of the raw, first derivative, and second derivative FTIR spectra. The findings showed that FTIR spectroscopy combined with multivariate analyses has a considerable capability to detect and quantify adulterants in lemon essential oil.

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.

New Drug Discovery from Medicinal Plants and Phytoconstituents for Depressive Disorders

BACKGROUND & OBJECTIVE

Depression, a risk factor for several serious diseases, is a highly prevalent and life-threatening psychiatric disorder. It can affect the individual's position in life and reduce the living standards. The research on the use of medicinal plants in treating this disease has increased enormously because of the possible low rehabilitation rate and side effects of available synthetic drugs, such as sexual dysfunction, nausea, fatigue, insomnia, hypersomnia, and weight gain.

CONCLUSION

Therefore, this review aimed to draw attention to the antidepressant effects of culinary herbs and traditional medicinal plants and their active components, thereby promoting their use in the development of more potent antidepressants with improved side effect profile.

Garlic essential oil mediates acute and chronic mild stress-induced depression in rats via modulation of monoaminergic neurotransmission and brain-derived neurotrophic factor levels

Garlic essential oil (GEO) and its major organosulfur component (diallyl disulfide, DADS) possess diverse biological properties; however, limited information on their antidepressant-like effects is available. This study is the first to investigate these effects of GEO using the forced swimming test (FST) and unpredictable chronic mild stress (UCMS) induced depression in rats. After oral administration for 28 consecutive days, GEO (25 and 50 mg per kg bw) significantly reduced the immobility time in the FST. Additionally, GEO and DADS significantly reversed the sucrose preference index decrease induced by 5 weeks of UCMS. GEO (25 mg per kg bw) effectively decreased the frontal cortex turnover ratio of serotonin (5-HT) and dopamine (DA), thus increasing the 5-HT and DA levels, with no hippocampal effects. Chronic GEO treatment increased hippocampal brain-derived neurotrophic factor (BDNF), c-AMP response element binding protein (CREB), and protein kinase B (AKT) expression, exhibiting its effects via monoamine neurotransmitter modulation and the BDNF-related signaling pathway.

Linking What We Eat to Our Mood: A Review of Diet, Dietary Antioxidants, and Depression

Studies have shown that diet and nutrition play significant roles in the prevention of depression and its clinical treatment. The present review aims to provide a clear understanding of the associations between diet patterns, specific foods, nutrients such as antioxidants, and depression. As a result, balanced dietary patterns such as the Mediterranean diet and certain foods such as fish, fresh vegetables, and fruits have been associated with a lower risk of depression or depressive symptoms, while high-fat Western diets and sugar-sweetened beverages have been associated with higher risk of depression or depressive symptoms. Dietary antioxidants such as green tea polyphenols or isoflavonoid intake have been negatively associated with depression or depressive symptoms. It is concluded that diet patterns, specific foods, and antioxidants play important roles in the prevention and clinical treatment of depression.

Syntheses of Benzo[d]Thiazol-2(3H)-One Derivatives and Their Antidepressant and Anticonvulsant Effects

Thirty-four new benzo[d]thiazol derivatives 2a–2i, 3a–3r, and 4a–4g were synthesized and investigated for their potential antidepressant and anticonvulsant effects. In a forced swimming test, 2c and 2d showed the highest antidepressant and anticonvulsant effects. 2c and 2d displayed a higher percentage decrease in immobility duration (89.96% and 89.62%, respectively) than that of fluoxetine (83.62%). In the maximal electroshock seizure test, 3n and 3q showed the highest anticonvulsant effect, with ED₅₀ values of 46.1 and 64.3 mg kg⁻¹, and protective indices of 6.34 and 4.11, respectively, which were similar to those of phenobarbital or valproate. We also found that the mechanism for the antidepressant activity of 2c and 2d may be via increasing the concentrations of serotonin and norepinephrine.

Self-microemulsifying Drug Delivery System for Improved Oral Delivery of Limonene: Preparation, Characterization, in vitro and in vivo Evaluation

The current investigation aimed at formulating self-microemulsifying drug delivery system (SMEDDS) to ameliorate oral bioavailability of a hydrophobic functional ingredient, limonene. Solubility test, compatibility test, and pseudo-ternary phase diagrams (PTPD) were adopted to screen the optimal compositions of limonene-SMEDDS (L-SMEDDS). The characteristics of this system assessed in vitro, mainly included determination of particle size distribution, observation of morphology via transmission electron microscopy (TEM), testing of drug release in different dissolution media, and evaluation of stability. The oral bioavailability study in vivo of the formulated limonene was performed in rats with the free limonene as the reference. Compared with the free limonene, the distribution study of L-SMEDDS was conducted in Kunming mice after oral administration. The optimized SMEDDS (ethyl oleate, 14.2%; Cremophor EL, 28.6%; isopropanol, 28.6%; and loaded limonene, 28.6%) under the TEM (about 100 nm) was spherical with no significant variations in size/appearance for 30 days at 4, 25, and 60°C. In comparison with free limonene, higher than 89.0% of limonene was released from SMEDDS within 10 min in different dissolution media. An in vivo study showed a 3.71-fold improved oral bioavailability of the formulated limonene compared to the free limonene. The tissue distribution results showed that limonene predominantly accumulated in the various tissues for the L-SMEDDS compared with the free limonene. Hence, L-SMEDDS could remarkably improve the concentration of limonene in the various organs. These findings hinted that the oral bioavailability of limonene could be improved via an effectual delivery system like SMEDDS.

Antidepressant-like activities of live and heat-killed Lactobacillus paracasei PS23 in chronic corticosterone-treated mice and possible mechanisms

Emerging evidence indicates that ingestion of specific probiotics, known as "psychobiotics", confer beneficial effects on mental health. This study investigated antidepressant-like effects and possible underlying mechanisms of Lactobacillus paracasei PS23 (PS23), live or heat-killed, in a mouse model of corticosterone-induced depression using fluoxetine as standard drug. PS23 were orally gavaged to mice from day 1 to 41 or fluoxetine from day 17 to 41 and injected with corticosterone from day 17 to 37. After the last corticosterone treatment, anxiety- and depression-like behaviors were tested within 4 days. On day 42, serum and brain tissue were collected 24 min after forced swim stress. Abnormal behavioral changes induced by corticosterone were ameliorated by treatment with live PS23 in open field and sucrose preference tests, with heat-killed PS23 in open field, forced swim and sucrose preference tests, and with fluoxetine in open field and forced swim tests. Furthermore, both live and heat-killed PS23 and fluoxetine reversed corticosterone-reduced protein levels of brain-derived neurotropic factor, mineralocorticoid, and glucocorticoid receptors in the hippocampus. In addition, live PS23 also reverses corticosterone-reduced serotonin levels in hippocampus, prefrontal cortex and striatum; whereas heat-killed PS23 reverses corticosterone-reduced dopamine levels in hippocampus and prefrontal cortex. And fluoxetine normalized reduced corticosterone level in serum. These studies showed that both live and heat-killed PS23 can reverse chronic corticosterone-induced anxiety- and depression-like behaviors and that may provide insights into the mechanism and a potential psychobiotic for depression management.

Antidepressant-like effects of water extract of Gastrodia elata Blume on neurotrophic regulation in a chronic social defeat stress model

ETHNOPHARMACOLOGY RELEVANCE

Gastrodia elata Blume (GE) is a traditional Chinese medicine commonly used to treat dizziness, epilepsy, paralysis and some emotional symptoms in east Asia. We previously showed that the water extract of Gastrodia elata Blume (WGE) possesses anti-depression like effects in a forced swimming test and chronic mild stress model.

AIM OF THE STUDY

The aim of this study was to investigate the antidepressant-like effects of WGE and potential mechanisms related to brain-derived neurotrophic factor (BDNF) regulation in mice exposed to chronic social defeat stress (CSDS) model.

MATERIALS AND METHODS

Fifty C57BL/6 mice were divided into 5 groups as follows: a control (CTL) group, CSDS group, and 3 WGE groups receiving 250, 500 or 1000mg/kg body weight in the CSDS model. Mice were administered WGE for 24 days by oral gavage, and the social defeat stress paradigm began on day 14, except for the control group. A social interaction test was conducted to evaluate the antidepressant-like effects of WGE. Blood samples were collected to measure serum corticosterone levels, and the brain was dissected to investigate the expression of BDNF-related signaling pathway proteins using western blotting.

RESULTS

Oral administration of WGE improved depression-like behaviors and stress-induced elevations of corticosterone. Further, WGE increased the protein expression of BDNF and promoted the hippocampal protein phosphorylation ratio of cAMP response element binding protein (CREB) and protein kinase B (Akt).

CONCLUSION

WGE exerts antidepressant-like effects on mice in a CSDS model, likely through activating of the BDNF/CREB/Akt pathway. Therefore, WGE has potential as a supplement or an adjuvant to prevent or treat clinical depressive disorders.

Anti-stress and neuronal cell differentiation induction effects of Rosmarinus officinalis L. essential oil

Background

Mood disorder accounts for 13 % of global disease burden. And while therapeutic agents are available, usually orally administered, most have unwanted side effects, and thus making the inhalation of essential oils (EOs) an attractive alternative therapy. Rosmarinus officinalis EO (ROEO), Mediterranean ROEO reported to improve cognition, mood, and memory, the effect on stress of which has not yet been determined. Here, the anti-stress effect of ROEO on stress was evaluated in vivo and in vitro.

Methods

Six-week-old male ICR mice were made to inhale ROEO and subjected to tail suspension test (TST). To determine the neuronal differentiation effect of ROEO in vitro, induction of ROEO-treated PC12 cells differentiation was observed. Intracellular acetylcholine and choline, as well as the Gap43 gene expression levels were also determined.

Results

Inhalation of ROEO significantly decreased the immobility time of ICR mice and serum corticosterone level, accompanied by increased brain dopamine level. Determination of the underlying mechanism in vitro revealed a PC12 differentiation-induction effect through the modulation of intracellular acetylcholine, choline, and Gap43 gene expression levels. ROEO activates the stress response system through the NGF pathway and the hypothalamus-pituitary-adrenal axis, promoting dopamine production and secretion. The effect of ROEO may be attributed to its bioactive components, specifically to α-pinene, one of its major compounds that has anxiolytic property.

Conclusions

The results of this study suggest that ROEO inhalation has therapeutic potential against stress-related psychiatric disorders.

Ophiocordyceps formosana improves hyperglycemia and depression-like behavior in an STZ-induced diabetic mouse model

Background

A newly defined Cordyceps species, Ophiocordyceps formosana (O. formosana) has been implicated in multitudinous bioactivities, including lowering glucose and cholesterol levels and modulating the immune system. However, few literatures demonstrate sufficient evidence to support these proposed functions. Although the use of Cordyceps spp. has been previously addressed to improve insulin insensitivity and improve the detrimental symptoms of depression; its mechanistic nature remains unsettled. Herein, we reveal the effects of O. formosana in ameliorating hyperglycemia accompanied with depression.

Methods

Diabetes was induced in mice by employing streptozotocin(STZ), a chemical that is toxic to insulin-producing β cells of the pancreas. These streptozotocin (STZ)-induced diabetic mice showed combined symptoms of hyperglycemia and depressive behaviors. Twenty-four STZ-induced mice were randomly divided into 3 groups subjected to oral gavage with 100 μL solution of either PBS or 25 mg/mL Ophiocordyceps formosana extract (OFE) or 2 mg/mL rosiglitazone (Rosi, positive control group). Treatments were administered once per day for 28 days. An additional 6 mice without STZ induction were treated with PBS to serve as the control group. Insulin sensitivity was measured by a glucose tolerance test and levels of adiponectin in plasma and adipose tissue were also quantified. Behavioral tests were conducted and levels of monoamines in various brain regions relating to depression were evaluated.

Results

HPLC analysis uncovered three major constituents, adenosine, D-mannitol and cordycepin, within O. formosana similar to other prestigious medicinal Cordyceps spp.. STZ-induced diabetic mice demonstrated decreased body weight and subcutaneous adipose tissue, while these symptoms were recovered in mice receiving OFE treatment. Moreover, the OFE group displayed improved insulin sensitivity and elevated adiponectin within the plasma and adipose tissue. The anti-depressive effect of OFE was observed in various depression-related behavior tests. Concurrently, neurotransmitters, like 5-HT and dopamine in the frontal cortex, striatum and hippocampus were found to be up-regulated in OFE-treated mice.

Conclusions

Our findings illustrated, for the first time, the medicinal merits of O. formosana on Type I diabetes and hyperglycemia-induced depression. OFE were found to promote the expression of adiponectin, which is an adipokine involved in insulin sensitivity and hold anti-depressive effects. In addition, OFE administration also displayed altered levels of neurotransmitters in certain brain regions that may have contributed to its anti-depressive effect. Collectively, this current study provided insights to the potential therapeutic effects of O. formosana extracts in regards to hyperglycemia and its depressive complications.

Neurological mechanism of Xiaochaihutang's antidepressant-like effects to socially isolated adult rats

Objectives

Xiaochaihutang (XCHT) has antidepressant effects in multiple animal models of depression in our previous studies. But the antidepressant effects and exact mechanisms of XCHT in a rat model of chronic social isolation stress (CSIS) have never been studied. We therefore aimed to investigate the effects of XCHT on depressive/anxiety-related behaviours of CSIS-exposed rats and understand the neurological mechanism involving neurogenesis.

Methods

We established the CSIS model and then investigated the effects of XCHT on behavioural change. HPLC-MS/MS was adopted to quantify neurotransmitter levels in the cerebrospinal fluid (CSF). Immunofluorescence technology was used to study the effects of XCHT on neurogenesis; while expressions of 5-HT1A receptor signalling pathway in the hippocampus were measured using Western blotting.

Key Findings

Xiaochaihutang significantly alleviated depressive/anxiety-like behaviours of CSIS-exposed rats. XCHT significantly regulated levels of monoamine neurotransmitters in the CSF without affecting Glu, GABA and ACh. XCHT also significantly increased neurogenesis in CSIS-exposed rats. Additionally, XCHT reversed CSIS-induced decrease of 5-HT1A receptor expression and promoted the expression of BDNF in the hippocampus.

Conclusion

Our results suggest that XCHT could significantly regulate the depressive/anxiety-like behaviours induced by CSIS, which are likely attributed to the promotion of hippocampal neurogenesis and neurotrophin expressions through the activation of serotonergic system.

Antidepressant-like effects of water extract of Gastrodia elata Blume in rats exposed to unpredictable chronic mild stress via modulation of monoamine regulatory pathways

ETHNOPHARMACOLOGY RELEVANCE

Gastrodia elata Blume (GE) is a traditional herbal medicine belonging to the Orchidaceae family, and has been used to manage neurological disorders for centuries. We have previously reported that its water extract (WGE) could improve the depressive-like behaviours in the forced swimming test (FST), an animal model of depression.

AIM OF THE STUDY

To investigate the antidepressant-like effects of WGE in rats exposed to unpredictable chronic mild stress (UCMS) model, and to explore its possible molecular mechanisms.

MATERIALS AND METHODS

UCMS rats were orally administered with WGE (0.5g/kg body weight) daily within the 4 weeks UCMS procedure. The sucrose preference test and the open field test were conducted to assess anhedonia and spontaneous behaviours, respectively. The cerebral turnover rates of monoamine neurotransmitters and the serum corticosterone levels were measured. In vitro direct and indirect monoamine oxidase A (MAO-A) inhibitory assays were employed to assess the possible antidepressant-like mechanisms of WGE (0.5mg/mL) and its major component, gastrodin (GAS, 15, 30 and 60μg/mL). Western blot was used to examine the expression of protein related to monoamine regulation, such as MAO-A and tyrosine hydroxylase (TH).

RESULTS

WGE significantly reversed the sucrose preference and other abnormal behaviours induced by 4 weeks of UCMS. WGE significantly restored the cerebral turnover rates of serotonin and dopamine and decreased serum corticosterone levels. WGE and gastrodin inhibited the activity and protein expression of MAO-A, and increased TH levels in PC12 cells.

CONCLUSION

The antidepressant-like effects of WGE and gastrodin might be mediated by the regulation of monoamine neurotransmitters, and therefore were beneficial in depression treatment as a complementary approach.

Structural Features and Potent Antidepressant Effects of Total Sterols and β-sitosterol Extracted from Sargassum horneri

The purified total sterols and β-sitosterol extracted from Sargassum horneri were evaluated for their antidepressant-like activity using the forced swim test (FST) and tail suspension test (TST) in mice. Total sterols and β-sitosterol significantly reduced the immobility time in the FST and TST. Total sterols were administered orally for 7 days at doses of 50, 100, and 200 mg/kg, and β-sitosterol was administered intraperitoneally at doses of 10, 20, and 30 mg/kg. β-sitosterol had no effect on locomotor activity in the open field test. In addition, total sterols and β-sitosterol significantly increased NE, 5-HT, and the metabolite 5-HIAA in the mouse brain, suggesting that the antidepressant-like activity may be mediated through these neurotransmitters.

Repeated, Intermittent Social Defeat across the Entire Juvenile Period Resulted in Behavioral, Physiological, Hormonal, Immunological, and Neurochemical Alterations in Young Adult Male Golden Hamsters

The developing brain is vulnerable to social defeat during the juvenile period. As complements of human studies, animal models of social defeat provide a straightforward approach to investigating the functional and neurobiological consequences of social defeats. Taking advantage of agonist behavior and social defeat in male golden hamster, a set of 6 experiments was conducted to investigate the consequences at multiple levels in young adulthood resulting from repeated, intermittent social defeats or “social threats” across the entire juvenile period. Male hamsters at postnatal day 28 (P28) were randomly assigned to either the social defeat, “social threat”, or arena control group, and they correspondingly received a series of nine social interaction trials (i.e., either social defeat, “social threat”, or arena control conditions) from P33 to P66. At the behavioral level (Experiment 1), we found that repeated social defeats (but not “social threats”) significantly impacted locomotor activity in the familiar context and social interaction in the familiar/unfamiliar social contexts. At the physiological and hormonal levels (Experiments 2 and 3), repeated social defeat significantly enhanced the cortisol and norepinephrine concentrations in blood. Enlargement of the spleen was also found in the social defeat and “social threat” groups. At the immunological level (Experiment 4), the social defeat group showed lower levels of pro-inflammatory cytokines in the hypothalamus and hippocampus but higher concentration of IL-6 in the striatum compared to the other two groups. At the neurochemical level (Experiment 5), the socially defeated hamsters mainly displayed reductions of dopamine, dopamine metabolites, and 5-HT levels in the striatum and decreased level of 5-HT in the hippocampus. In Experiment 6, an increase in the spine density of hippocampal CA1 pyramidal neurons was specifically observed in the “social threat” group. Collectively, our findings indicate that repeated, intermittent social defeats throughout entire adolescence in hamsters impact their adult responses at multiple levels. Our results also suggest that the “social threat” group may serve as an appropriate control. This study further suggest that the alterations of behavioral responses and neurobiological functions in the body and brain might provide potential markers to measure the negative consequences of chronic social defeats.

Anti-depressant effects of Gastrodia elata Blume and its compounds gastrodin and 4-hydroxybenzyl alcohol, via the monoaminergic system and neuronal cytoskeletal remodeling

ETHNOPHARMACOLOGY RELEVANCE

Gastrodia elata Blume is a highly valuable traditional Chinese medicine used in the treatment of depression. However, compounds with antidepressant effects in water extracts of G. elata Bl. (WGE) have not been identified. The aims of this study were to determine the major antidepressant compound in WGE and to evaluate the antidepressant effects of WGE and its active compounds which involved the monoaminergic system and neuronal cytoskeletal remodeling.

MATERIALS AND METHODS

Gastrodin (GAS) and 4-hydroxybenzyl alcohol (HBA) in WGE, were analyzed with high-performance liquid chromatography (HPLC)-ultraviolet detection. The forced swimming test (FST) was used to induce depression-like symptoms in 9 weeks old male Sprague-Dawley rats. The open field test (OFT) was used to measure anxiety after WGE, GAS, and HBA treatments. The levels of monoamine such as serotonin (5-HT), dopamine (DA), and their metabolites 5-hydroxyindoleacetic acid (5-HIAA), 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) were measured using HPLC-electrochemical detection. Western blotting was used to examine the 5-HT1A receptor and the neuronal cytoskeleton remodeling-related proteins, Slit, dihydropyrimidinase-related protein 2 (DPYSL2, also called CRMP2), Ras homologous member A (RhoA), and profilin 1 (PFN1) in vivo. Slit1 expression was evaluated in Hs683 cell line after treated with WGE (0.5mg/mL), GAS (50, 100 and 100μM), and HBA (50, 100 and 100μM).

RESULTS

Oral administration of WGE (500mg/kg bw), GAS (100mg/kg bw), and HBA (100mg/kg bw) exhibited the anti-depressant effect by significantly reducing the immobility time in FST, monoamine metabolism including the 5-HT to 5-HIAA in the hippocampus and DA to DOPAC and HVA ratios in the frontal cortex, amygdala, and hippocampus. In the hippocampus, the expression of the neuronal cytoskeleton remodeling-related negative regulators Slit1 and RhoA were significantly down-regulated. In addition, the positive regulators CRMP2 and PFN1 were significantly up-regulated following GAS, HBA, and WGE treatments. Moreover, WGE, GAS, and HBA were directly down-regulated Slit1 expression in Hs683 cells.

CONCLUSION

WGE, GAS, and HBA exhibited potential anti-depressant effects in rats by decreasing monoamine metabolism and modulated cytoskeleton remodeling-related protein expression in the Slit-Robo pathway. These results suggest that WGE can be used as agent for depressive prevention.

Fucosterol, a sterol extracted from Sargassum fusiforme, shows antidepressant and anticonvulsant effects

We previously showed that extracts of Sargassum fusiforme significantly reduce immobility time in the forced swim test and tail suspension test, suggesting that these extracts possess antidepressant-like effects. Here, fucosterol extracted from S. fusiforme was evaluated for antidepressant and anticonvulsant activities in mice. Fucosterol (10, 20, 30 and 40mg/kg) significantly shortened immobility time in the forced swim test and tail suspension test for30min after treatment but had no effect on locomotor activity in the open field test. Fucosterol significantly increased serotonin, norepinephrine and the metabolite 5-hydroxyindoleacetic acid in mouse brain, suggesting that the effects of fucosterol may be mediated through these neurotransmitters. As assessed using maximal electroshock, fucosterol (20, 40, 100mg/kg) possessed anticonvulsant activity, whereas rotarod toxicity test results indicated that fucosterol did not induce neurotoxicity at the same dose levels in mice. Thus, fucosterol may be a useful antidepressant adjunct candidate for treating depression in patients with epilepsy. A significant increase in hippocampal brain-derived neurotrophic factor (BDNF) levels was found in the fucosterol 20mg/kg group (P<0.05). Our findings suggested that fucosterol may possess an antidepressant-like effect, which may be mediated by increasing central BDNF levels.

Antidepressant-like effects of the hydroalcoholic extracts of Hemerocallis citrina and its potential active components

Background

Herbal therapies are potential alternatives and adjuncts for depression treatment. The present study aims to investigate the antidepressant-like effects of hydroalcoholic Hemerocallis citrina extracts and its potential neuropharmacological components.

Methods

Hydroalcoholic H. citrina extracts were phytochemically analyzed. Behavioral models, including tail suspension tests and open field tests, were performed to evaluate the antidepressant-like effects of the extracts. A possible mechanism was explored by analyzing brain monoamine neurotransmitters. Toxicity and histopathological analyses were performed to determine whether or not the extracts are safe for oral administration.

Results

The antidepressant-like effects of hydroalcoholic H. citrina extracts were mainly related to flavonoids, especially rutin and hesperidin. The extract prepared using 75% ethanol (i.e., HCE75) exhibited the highest active flavonoid content and activity. Orally administered 400 mg/kg of HCE75 significantly induced an antidepressant-like effect, whereas the combination of equivalent rutin and hesperidin dosages exhibited the same profiles. Isobologram analysis showed sub-additive antidepressant interactions between rutin and hesperidin. HCE75 (400 mg/kg, p.o.) increased the serotonin and dopamine levels in the central nervous system. Mortality and lesions were not observed upon oral administration of up to 5000 mg/kg HCE75.

Conclusions

The antidepressant-like effects of hydroalcoholic H. citrina extracts are mainly related to flavonoids, especially rutin and hesperidin. The serotonergic and dopaminergic systems may have major roles. The active extract is toxicologically safe for oral administration.

Changes in 5-hydroxytryptamine and cortisol plasma levels in menopausal women after inhalation of clary sage oil

The purpose of this study was to examine the antidepressant-like effects of clary sage oil on human beings by comparing the neurotransmitter level change in plasma. The voluntary participants were 22 menopausal women in 50's. Subjects were classified into normal and depression tendency groups using each of Korean version of Beck Depression Inventory-I (KBDI-I), KBDI-II, and Korean version of Self-rating Depression Scale. Then, the changes in neurotransmitter concentrations were compared between two groups. After inhalation of clary sage oil, cortisol levels were significantly decreased while 5-hydroxytryptamine (5-HT) concentration was significantly increased. Thyroid stimulating hormone was also reduced in all groups but not statistically significantly. The different change rate of 5-HT concentration between normal and depression tendency groups was variable according to the depression measurement inventory. When using KBDI-I and KBDI-II, 5-HT increased by 341% and 828% for the normal group and 484% and 257% for the depression tendency group, respectively. The change rate of cortisol was greater in depression tendency groups compared with normal groups, and this difference was statistically significant when using KBDI-II (31% vs. 16% reduction) and Self-rating Depression Scale inventory (36% vs. 8.3% reduction). Among three inventories, only KBDI-II differentiated normal and depression tendency groups with significantly different cortisol level. Finally, clary sage oil has antidepressant-like effect, and KBDI-II inventory may be the most sensitive and valid tool in screening for depression status or severity.