Anxiolytic-like effect of lavender essential oil inhalation in mice: participation of serotonergic but not GABAA/benzodiazepine neurotransmission

Lavender essential oil alleviates depressive-like behavior in alcohol-withdrawn rats: Insights from gut metabolites and hippocampal transcriptome analysis

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on the diversity of gut microbiota, metabolites, and differential gene expression in the hippocampus of alcohol-withdrawn depressive rats.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activity in the central zone of the open field test, and prolonged immobility time in the forced swim test in alcohol-withdrawn depressive rats, indicating the amelioration of depressive states following lavender essential oil inhalation. 16 S rDNA sequencing analysis revealed a significant reduction in Bacteroidota and Muribaculaceae in the gut of alcohol-withdrawn depressive rats, whereas lavender essential oil significantly increased the relative abundance of Muribaculaceae and other bacterial species.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 This study identified elevated expression of Trpv4 and Calml4 in the hippocampal region of alcohol-withdrawn depressed rats and showed that lavender essential oil inhalation regulated aberrantly expressed genes.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

Multiplicative Effects of Essential Oils and Other Active Components on Skin Tissue and Skin Cancers

Naturally derived essential oils and their active components are known to possess various properties, ranging from anti-oxidant, anti-inflammatory, anti-bacterial, anti-fungal, and anti-cancer activities. Numerous types of essential oils and active components have been discovered, and their permissive roles have been addressed in various fields. In this comprehensive review, we focused on the roles of essential oils and active components in skin diseases and cancers as discovered over the past three decades. In particular, we opted to highlight the effectiveness of essential oils and their active components in developing strategies against various skin diseases and skin cancers and to describe the effects of the identified essential-oil-derived major components from physiological and pathological perspectives. Overall, this review provides a basis for the development of novel therapies for skin diseases and cancers, especially melanoma.

Anxiety-Reducing Effects of Lavender Essential Oil Inhalation: A Systematic Review

Anxiety disorders are the most prevalent and disabling mental disorders, causing health-related burdens. With the increasing demand for and interest in safe and acceptable anxiolytics, several studies report the anxiolytic effects of lavender aromatherapy, providing evidence of its physiological and psychological effects. However, existing reviews comprehensively cover the effects of different modes of delivering aromatherapy. Therefore, this review assesses the efficacy of lavender essential oil inhalation in reducing anxiety. The titles and abstracts of relevant articles published over the last five years were searched in PubMed, Web of Science, and Scopus databases. This review only included clinical trials that utilized lavender inhalation for anxiety treatment. Eleven studies comprising 972 participants were included. Of these, 10 reported significantly decreased anxiety levels after lavender oil inhalation. The physiological measures of vital signs, including blood pressure, heart rate, respiratory rate, pulse, and saturation, were conducted in three trials, showing that lavender oil inhalation could physiologically affect anxiety levels. Lavender oil inhalation is a safe and feasible anxiolytic intervention for treating people with diverse types of anxiety. Data from further studies with a high-quality design and accurate information are necessary to confirm the validity of these findings and elucidate the anxiety-reducing mechanisms of lavender inhalation.

Effects of ortho-eugenol on anxiety, working memory and oxidative stress in mice

Ortho-eugenol is a synthetic derivative from eugenol, the major compound of clove essential oil, which has demonstrated antidepressant and antinociceptive effects in pioneering studies. Additionally, its effects appear to be dependent on the noradrenergic and dopaminergic systems. Depression and anxiety disorders are known to share a great overlap in their pathophysiology, and many drugs are effective in the treatment of both diseases. Furthermore, high levels of anxiety are related to working memory deficits and increased oxidative stress. Thus, in this study we investigated the effects of acute treatment of ortho-eugenol, at 50, 75 and 100 mg/kg, on anxiety, working memory and oxidative stress in male Swiss mice. Our results show that the 100 mg/kg dose increased the number of head-dips and reduced the latency in the hole-board test. The 50 mg/kg dose reduced malondialdehyde levels in the prefrontal cortex and the number of Y-maze entries compared to the MK-801-induced hyperlocomotion group. All doses reduced nitrite levels in the hippocampus. It was also possible to assess a statistical correlation between the reduction of oxidative stress and hyperlocomotion after the administration of ortho-eugenol. However, acute treatment was not able to prevent working memory deficits. Therefore, the present study shows that ortho-eugenol has an anxiolytic and antioxidant effect, and was able to prevent substance-induced hyperlocomotion. Our results contribute to the elucidation of the pharmacological profile of ortho-eugenol, as well as to direct further studies that seek to investigate its possible clinical applications.

Aromatherapy for the brain: Lavender's healing effect on epilepsy, depression, anxiety, migraine, and Alzheimer's disease: A review article

Neurological diseases affect the nervous system, including the brain, spinal cord, cranial nerves, nerve roots, autonomic nervous system, neuromuscular junctions, and muscles. Herbal medicine has long been used to cure these diseases. One of these plants is lavender, which is composed of various compounds, including terpenes, such as linalool, limonene, triterpenes, linalyl acetate, alcohols, ketones, polyphenols, coumarins, cineole, and flavonoids. In this review, the literature was searched using scientific search engines and databases (Google Scholar, Science Direct, Scopus, and PubMed) for papers published between 1982 and 2020 via keywords, including review, lavender, and neurological disorders. This plant exerts its healing effect on many diseases, such as anxiety and depression through an inhibitory effect on GABA. The anti-inflammatory effects of this plant have also been documented. It improves depression by regulating glutamate receptors and inhibiting calcium channels and serotonergic factors, such as SERT. Its antiepileptic mechanism is due to an increase in the inhibitory effect of GABA and potassium current and a decrease in sodium current. Therefore, many vegetable oils are also used in herbal medicine. In this review, the healing effect of lavender on several neurological disorders, including epilepsy, depression, anxiety, migraine, and Alzheimer's disease was investigated. All findings strongly support the traditional uses of lavender. More clinical studies are needed to investigate the effect of the plants' pharmacological active constituents on the treatment of life-threatening diseases in humans. The limitations of this study are the low quality and the limited number of clinical studies. Different administration methods of lavender are one of the limitations of this review.

Aromatherapy in anxiety, depression, and insomnia: A bibliometric study and visualization analysis

Aromatherapy is a natural treatment method that uses essential oils (EOs) extracted from aromatic plants; EOs and their components exhibit a wide range of pharmacological activities, with a special focus on their implementation toward mental disorders, such as anxiety and depression. This study aimed to identify the scientific output and activity related to aromatherapy in anxiety, depression, and insomnia through bibliometric approaches. In this bibliometric study, we utilized CiteSpace and VOSviewer to evaluate the Web of Science Core Collection publications and to build visualizing maps to analyze the research progress on this topic between 2001 and 2021. A total of 1159 original and review articles in English, published in 578 different peer-reviewed journals by 260 authors, were identified. In the recent two decades, there was a steady increase in the number of published articles, especially in the following five years. All publications were distributed among 88 countries/regions. The United States had the most publications, with 188 (16.22%) articles, followed by China [131 (11.30%)], Brazil [110 (9.49%)], and Japan [85 (7.33%)]. Most studies were published in the Journal of Ethnopharmacology, and Physiology & Behavior was the most cited journal. Hritcu L was the top published scientist and Gupta SC was the most frequently co-cited. The knowledge base of this field research mainly included the related efficacy of aromatherapy/EOs, application status, and biochemical mechanism. And the keyword co-occurrence analysis revealed that the topics "oxidative stress," "chemical composition," "systematic review," and "sleep quality" were research frontiers. In conclusion, this comprehensive bibliometric study provides an updated perspective on research hotspots of aromatherapy in anxiety or depression and developmental tendencies of natural remedies for mental health. In addition, this study could also provide valuable information for research teams, practitioners, and decision-makers when designing and implementing natural treatment methods for mental health-promoting interventions for individuals with mood disorders.

Screening for Neuroprotective and Rapid Antidepressant-like Effects of 20 Essential Oils

Depression is a serious psychiatric disorder with high prevalence, and the delayed onset of antidepressant effects remains a limitation in the treatment of depression. This study aimed to screen essential oils that have the potential for rapid-acting antidepressant development. PC12 and BV2 cells were used to identify essential oils with neuroprotective effects at doses of 0.1 and 1 µg/mL. The resulting candidates were treated intranasally (25 mg/kg) to ICR mice, followed by a tail suspension test (TST) and an elevated plus maze (EPM) after 30 min. In each effective essential oil, five main compounds were computationally analyzed, targeting glutamate receptor subunits. As a result, 19 essential oils significantly abolished corticosterone (CORT)-induced cell death and lactate dehydrogenase (LDH) leakage, and 13 reduced lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6). From in vivo experiments, six essential oils decreased the immobility time of mice in the TST, in which Chrysanthemum morifolium Ramat. and Myristica fragrans Houtt. also increased time and entries into the open arms of the EPM. Four compounds including atractylon, α-curcumene, α-farnesene, and selina-4(14),7(11)-dien-8-one had an affinity toward GluN1, GluN2B, and Glu2A receptor subunits surpassed that of the reference compound ketamine. Overall, Atractylodes lancea (Thunb.) DC and Chrysanthemum morifolium Ramat essential oils are worthy of further research for fast-acting antidepressants through interactions with glutamate receptors, and their main compounds (atractylon, α-curcumene, α-farnesene, and selina-4(14),7(11)-dien-8-one) are predicted to underlie the fast-acting effect.

Role of 5-HT1A receptors in the basolateral amygdala on 3,4-methylenedioxymethamphetamine-induced prosocial effects in mice

3,4-methylenedioxymethamphetamine (MDMA), a recreational drug, induces euphoric sensations and psychosocial effects, such as increased sociability and empathy. Serotonin, also called 5-hydroxytryptamine (5-HT), is a neurotransmitter that has been associated with MDMA-induced prosocial effects. However, the detailed neural mechanisms remain elusive. In the present study, we investigated whether 5-HT neurotransmission in the medial prefrontal cortex (mPFC) and the basolateral nucleus of amygdala (BLA) is involved in MDMA-induced prosocial effects using the social approach test in male ICR mice. Systemic administration of (S)-citalopram, a selective 5-HT transporter inhibitor, before administration of MDMA failed to suppress MDMA-induced prosocial effects. On the other hand, systemic administration of the 5-HT_1A receptor antagonist WAY100635, but not 5-HT_1B, 5-HT_2A, 5-HT_2C, or 5-HT₄ receptor antagonist, significantly suppressed MDMA-induced prosocial effects. Furthermore, local administration of WAY100635 into the BLA but not into the mPFC suppressed MDMA-induced prosocial effects. Consistent with this finding, intra-BLA MDMA administration significantly increased sociability. Together, these results suggest that MDMA induces prosocial effects through the stimulation of 5-HT_1A receptors in the BLA.

Antinociceptive and anxiolytic-like effects of Lavandula angustifolia essential oil on rat models of orofacial pain

BACKGROUND

Nociceptive and inflammatory orofacial pain is highly prevalent in the population, which justifies the search for safer analgesics. There is increasing evidence of the analgesic and anxiolytic potential of Lavandula angustifolia essential oil (LAV EO), which may represent, when administered through inhalation, may represent a safer alternative for pain treatment.

OBJECTIVE

to evaluate whether LAV EO has antinociceptive effect in the formalin test, and anti-hyperalgesic and anxiolytic-like effects in rats subjected to a model of orofacial postoperative pain.

METHODOLOGY

Female Wistar rats were exposed to LAV EO (5%) by inhalation for 30 minutes. After exposure, animals were injected with formalin (2.5%, 50 μL) or saline into the hind paw or upper lip and the number of flinches or facial grooming time, respectively, were evaluated. Likewise, on day 3 after intraoral mucosa incision, the animals were exposed to LAV EO and facial mechanical, and heat hyperalgesia were assessed. The influence of LAV EO inhalation on anxiety-like behavior was assessed in operated rats by testing them on the open field (OF) and elevated plus maze (EPM).

RESULTS

LAV EO reduced the phase II of the paw formalin test and both phases of the orofacial formalin test. On day three post-incision, LAV EO reduced heat and mechanical hyperalgesia, from 30 minutes up to three hours, and reduced the anxiety-like behavior in operated rats without causing locomotor deficit.

CONCLUSION

LAV EO inhalation results in antinociceptive and anxiolytic-like effects in orofacial pain models, which encourages further studies on LAV EO indications and effectiveness on orofacial pain conditions.

[Impact of essential oil vapors inhalation on blood pressure in patients with hypertension]

Increase of patients with hypertension in the world determines the search for new, accessible, easily applicable and mildly effective antihypertensive agents, particularly essential oils (EO). Currently available studies of the EO impact on blood pressure do not allow to assess the efficiency of such therapy.

OBJECTIVE

To perform the comparative study of antihypertensive effects of inhalation with EO vapors of various composition.

MATERIAL AND METHODS

The investigation included 849 women aged 55-89 years with hypertension. Two examination series were done: 10- and 20-minute duration procedures. Trial subjects were divided into control (psychorelaxation procedure) and experimental (psychorelaxation procedure combined with the EO inhalation of common basil, Italian immortelle, clove tree, common hyssop, cardamom, coriander, Caucasian nepeta, nepeta cataria, spicate lavender, bay laurel, the sort «Oxamitov» of brook-mint, the sorts «Prilutskaya», «Udaichanka», «Ukrainian» of pepper mint, the Siberian fir, Tauric wormwood, the sort «Crimean red» of rose, rosmarinus officinalis, Scotch pine, fennel, mountain savory, garden savory and clary sage; EO concentration in air - 1 mg/m³) groups. Systolic and diastolic blood pressure, heart rate were measured, as well as the coefficient of blood circulation efficiency and Robinson index were calculated before and after the examination in trial subjects.

RESULTS

It has been established that the EO of clary sage, bay laurel, Caucasian nepeta and the sort «Oxamitov» of brook-mint have antihypertensive action at both 10-minute and 20-minute exposure. The antihypertensive action of EO of common basil, clove tree, coriander, nepeta cataria, the sort «Crimean red» of rose, rosmarinus officinalis, garden savory was found after 10-minute exposure. There was no antihypertensive action in EO application of Italian immortelle, common hyssop, spicate lavender, the sorts «Prilutskaya», «Ukrainian», «Udaichanka» of pepper mint, Siberian fir, tauric wormwood, Scotch pine and fennel.

CONCLUSION

The EO vapors' inhalation of clary sage, bay laurel, Caucasian nepeta, the sort «Oxamitov» of brook-mint, common basil, clove tree, coriander, nepeta cataria, the sort «Crimean red» of rose, rosmarinus officinalis and garden savory can be a promising method to reduce blood pressure in patients with hypertension.

Anxiolytic-like Effect of Inhaled Cinnamon Essential Oil and Its Main Component Cinnamaldehyde in Animal Models

Aromatherapy is one of the most common safer alternative treatments for psychiatric disorders with fewer side effects than conventional drugs. Here, we investigated the effects of cinnamon essential oil (CIEO) inhalation on mouse behaviors by performing different behavioral tests. CIEO inhalation showed anxiolytic effects in the elevated plus maze test, as inferred from increased time spent in open arms and decreased time spent in closed arms. Moreover, the CIEO treatment enhanced social behavior by increasing the total contact number, time spent in the center, distance traveled in the center, and total distance in the social interaction test. However, CIEO inhalation did not have any effect on performance in the open field test, tail suspension test, forced swimming test, and Y maze tests. The microarray analysis indicated that the CIEO treatment downregulated 17 genes and upregulated 15 genes in the hippocampus. Among them, Dcc, Egr2, and Fos are the most crucial genes that are involved in anxiety-related biological processes and pathways, including the regulation of neuronal death and neuroinflammation. Gas chromatography/mass spectrometry analysis revealed that cinnamaldehyde is the main component of CIEO. Cinnamaldehyde recovered MK-801-induced anxiety-related changes in the electroencephalogram power spectrum in zebrafish. Taken together, our findings suggest that CIEO and its main component cinnamaldehyde have an anxiolytic effect through the regulation of the expression of genes related to neuroinflammatory response and neuronal death.

Effects of odors on sleep quality in 139 healthy participants

The present study aimed to systematically examine whether laurinal, orange odor, and a specifically designed "perfume" influence sleep quality. During sleep, healthy participants (n = 139) were presented with odor or no odor through nose clips for fourteen consecutive nights (phase one). We collected physiological parameters together with subjective reports. Later on, longer lasting effects of this manipulation were examined for the following fourteen nights (phase two) without exposition to odors. Additionally, olfactory, cognitive and non-cognitive measures were conducted before phase one, between both phases and after phase two. One-way analyses of variance for repeated measures with nights and condition (1 vs 2) as the within-subject factor and odor condition (0, 1, 2 or 3) together with odor pleasantness rating as between-subject factor, was employed to analyse data. Overall, the present results demonstrated that the odor condition in comparison to control had no consistent effect on sleep in healthy participants which can be possibly explained by exposure to odors via nose clips. However, the analyses indicated that the individual pleasantness of odors enhanced the positive assessment of sleep quality. Altogether, the present results indicate that the subjective perception of an odor's hedonic value appears to be crucial for sleep quality, not the odors themselves.

Neuroprotective Natural Products’ Regulatory Effects on Depression via Gut–Brain Axis Targeting Tryptophan

L-tryptophan (Trp) contributes to regulating bilateral communication of the gut–brain axis. It undergoes three major metabolic pathways, which lead to formation of kynurenine, serotonin (5-HT), and indole derivatives (under the control of the microbiota). Metabolites from the principal Trp pathway, kynurenic acid and quinolinic acid, exhibit neuroprotective activity, while picolinic acid exhibits antioxidant activity, and 5-HT modulates appetite, sleep cycle, and pain. Abnormality in Trp plays crucial roles in diseases, including depression, colitis, ulcer, and gut microbiota-related dysfunctions. To address these diseases, the use of natural products could be a favorable alternative because they are a rich source of compounds that can modulate the activity of Trp and combat various diseases through modulating different signaling pathways, including the gut microbiota, kynurenine pathway, and serotonin pathway. Alterations in the signaling cascade pathways via different phytochemicals may help us explore the deep relationships of the gut–brain axis to study neuroprotection. This review highlights the roles of natural products and their metabolites targeting Trp in different diseases. Additionally, the role of Trp metabolites in the regulation of neuroprotective and gastroprotective activities is discussed. This study compiles the literature on novel, potent neuroprotective agents and their action mechanisms in the gut–brain axis and proposes prospective future studies to identify more pharmaceuticals based on signaling pathways targeting Trp.

The Effect of Aromatherapy on Blood Pressure and Stress Responses by Inhalation and Foot Massage in Patients With Essential Hypertension: Randomized Clinical Trial

A 3-arm, parallel group, randomized clinical trial examines the effect of aromatherapy through inhalation and foot massage on blood pressure and stress response in patients with essential hypertension. Lavender oil reduced blood pressure, heart rate, serum cortisol, and subjective anxiety in hypertensive patients.

Aromas Influencing the GABAergic System

Aromas have a powerful influence in our everyday life and are known to exhibit an array of pharmacological properties, including anxiolytic, anti-stress, relaxing, and sedative effects. Numerous animal and human studies support the use of aromas and their constituents to reduce anxiety-related symptoms and/or behaviours. Although the exact mechanism of how these aromas exert their anxiolytic effects is not fully understood, the GABAergic system is thought to be primarily involved. The fragrance emitted from a number of plant essential oils has shown promise in recent studies in modulating GABAergic neurotransmission, with GABA_A receptors being the primary therapeutic target. This review will explore the anxiolytic and sedative properties of aromas found in common beverages, such as coffee, tea, and whisky as well aromas found in food, spices, volatile organic compounds, and popular botanicals and their constituents. In doing so, this review will focus on these aromas and their influence on the GABAergic system and provide greater insight into viable anxiety treatment options.

Odors associated with neonatal experiences with the dam have enhanced anxiolytic effects in rat

Odor stimuli are widely reported to promote relaxation and reduce anxiety in humans and rodents. However, it remains unclear if this anxiolytic efficacy can be further enhanced by association with positive experiences. Therefore, we compared the effects of a novel odor to a familiar odor previously paired with a positive experience on anxiety-like behaviors in rats. One group of Wistar-Imamichi female and male pups was exposed to an odor stimulus with their dams during postnatal days (PNDs) 8-12, whereas another control group was exposed to perfused air during the same period. Starting on PND 42, all animals were examined in the open field test (OFT) and elevated plus maze (EPM) test during exposure to scent-free air (vehicle), a novel odor, or the positive-familiar odor from postnatal exposure. In the EPM, female rats entered open arms with all 4 paws (complete entry) more frequently and spent more time on open arms during exposure to the positive-familiar odor than during exposure to air or a novel odor, whereas partial open arm entries with forepaws only were increased during exposure to both novel and positive-familiar odors compared to air. In contrast, male rats demonstrated no significant increase in open arm activity during positive-familiar odor exposure, but did show equally reduced grooming frequency during novel and familiar-positive odor exposure in the OFT. Exposure to positive-familiar odors may be an effective and safe method for anxiety reduction, especially in females.

Traditional Herbal Remedies Used for Managing Anxiety and Insomnia in Italy: An Ethnopharmacological Overview

Anxiety and insomnia are among the most common mental health disorders and are a major cause of disability around the world. Traditional herbal medicines are receiving significant attention in global health debates. Several Italian regions maintain rural traditions and are among the most extensively studied areas of Europe regarding medicinal plant uses. The present overview aims to highlight the use of wild and cultivated plants, specifically as sedatives and for insomnia treatment in Italy, and to collect, analyze, and summarize the available literature about their pharmacological activity as well as clinical and pre-clinical studies concerning the most cited plants. In total, 106 wild taxa are used in Italy for sedative purposes. The plant species belong to 76 genera and 32 families, of which the most cited are Asteraceae (24.2%) and Lamiaceae (21.1%). Leaves (29%) and flowers (27%) are the plant parts mostly used as infusion (70%) and decoction (25%). Out of 106 taxa documented, only the most cited are analyzed in this overview (A. arvensis L., C. nepeta L., C. monogyna Jacq., H. lupulus L., L. nobilis L., L. angustifolia Mill., M. sylvestris L., M. chamomilla L., M. officinalis L., O. basilicum L., P. rhoeas L., P. somniferum L., R. officinalis L., T. platyphyllus Scop., and V. officinalis L.). Among the fifteen species selected, only seven have been studied for their pharmacological activity as hypnotic-sedatives. Future pre-clinical and clinical studies are needed to better clarify the mechanism of action of bioactive compounds and confirm the potential of these alternative therapies.

Lavender aromatherapy: A systematic review from essential oil quality and administration methods to cognitive enhancing effects

Modern society is reviving the practice of aromatherapy, and lavender is reported being the most worldwide purchased plant for essential oil (EO) extraction. Since recent studies reported cognitive enhancing effects of lavender besides the hypno-inducing effects, a literature review is needed. Considering EO quality and diffusion devices, we conducted a systematic review on the effects of lavender EO inhalation on arousal, attention and memory in healthy subjects. Starting from this new multidisciplinary perspective, cognitive effects were reviewed to link outcomes to effective and reproducible protocols. A systematic search on MEDLINE, ERIC, PsycInfo, Google Scholar, and Scopus databases using Cognitive Atlas and plant-related keywords was conducted. Among the 1,203 articles yielded, 11 met eligibility criteria. Subjects administered with lavender EO displayed arousal decrease and sustained attention increase. Controversial results emerged regarding memory. Lack of EO quality assessment and protocols heterogeneity did not allow assessing whether different EO composition differentially modulates cognition and whether placebo effect can be discerned from EO effect itself. However, GABAergic pathway modulation exerted by linalool, a major lavender EO constituent, might explain cognitive functions empowerment. We speculate aromatherapy could be a burgeoning cognition enhancing tool, although further investigation is required to reach robust conclusions.

Analgesic Potential of Terpenes Derived from Cannabis sativa

Pain prevalence among adults in the United States has increased 25% over the past two decades, resulting in high health-care costs and impacts to patient quality of life. In the last 30 years, our understanding of pain circuits and (intra)cellular mechanisms has grown exponentially, but this understanding has not yet resulted in improved therapies. Options for pain management are limited. Many analgesics have poor efficacy and are accompanied by severe side effects such as addiction, resulting in a devastating opioid abuse and overdose epidemic. These problems have encouraged scientists to identify novel molecular targets and develop alternative pain therapeutics. Increasing preclinical and clinical evidence suggests that cannabis has several beneficial pharmacological activities, including pain relief. Cannabis sativa contains more than 500 chemical compounds, with two principle phytocannabinoids, Δ9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD). Beyond phytocannabinoids, more than 150 terpenes have been identified in different cannabis chemovars. Although the predominant cannabinoids, Δ9-THC and CBD, are thought to be the primary medicinal compounds, terpenes including the monoterpenes β-myrcene, α-pinene, limonene, and linalool, as well as the sesquiterpenes β-caryophyllene and α-humulene may contribute to many pharmacological properties of cannabis, including anti-inflammatory and antinociceptive effects. The aim of this review is to summarize our current knowledge about terpene compounds in cannabis and to analyze the available scientific evidence for a role of cannabis-derived terpenes in modern pain management. SIGNIFICANCE STATEMENT: Decades of research have improved our knowledge of cannabis polypharmacy and contributing phytochemicals, including terpenes. Reform of the legal status for cannabis possession and increased availability (medicinal and recreational) have resulted in cannabis use to combat the increasing prevalence of pain and may help to address the opioid crisis. Better understanding of the pharmacological effects of cannabis and its active components, including terpenes, may assist in identifying new therapeutic approaches and optimizing the use of cannabis and/or terpenes as analgesic agents.

Satureja montana L. essential oil various dosages effect on the main rats’ biological features

An application of natural antioxidants remains the focus of research groups. The effect of Satureja montana L. essential oil in various doses on the main biological characteristics of Wistar rats was the main aim of the study. The intensification of protein metabolism in the blood plasma of rats on the background of the use of Satureja montana L. essential oil was noted. Total protein increases by 17.9 – 19.7%, and albumin by 27.6% in rats of the experimental group received the essential oil at a dose of 0.6 ml per kg of feed. A significant increase in the AST level in control group rats to 207.3 U.L-1 was revealed. Its one to a certain extent indicates the hepatoprotective effect of mountain savory oil and a decrease in inflammatory processes in the organs of the gastrointestinal tract in the conditions of cell maintenance of rats of the experimental groups. Gastric epithelium thickness of rats of both experimental groups was lower than the control animals. But it did not bear any signs of atrophy. The difference of this indicator in comparison with control was 12.75 μm (p ≤0.05) in the second group and it was reliable. The number of chief stomach cells increases in animals of the experimental groups, which may indicate a greater enzymatic activity. An increased dose of mountain savory oil contributes to the formation of more damage to hepatocytes on the periphery of the liver lobule. Thus, the relationship between liver enzymes and the state of peripheral hepatocytes was noted.

Musk (Moschus moschiferus) Attenuates Changes in Main Olfactory Bulb of Depressed Mice: Behavioral, Biochemical, and Histopathological Evidence

BACKGROUND

Musk (Moschus moschiferus) has been described to have a significant impact on the central nervous system, as well as anticonvulsion and antidepressant effects. This study was designed to evaluate the efficacy of musk in alleviating alterations induced in olfactory bulb of depressed mice exposed to chronic stress and identify the mechanism behind it.

METHODS

Fifty male albino mice were divided into five groups (n = 10 each): control, musk, chronic unpredictable mild stress (CUMS), fluoxetine-treated, and musk-treated groups were included in this study. Behavioral changes and serum levels of corticosterone and proinflammatory cytokines included tumor necrosis factor α, interleukin 6, and oxidant/antioxidant profile were assessed at the end of the experiment. Main olfactory bulb (MOB) has been processed for histopathological examination. Gene expression of caspase-3, glial fibrillary acidic protein, and Ki67 were assessed in the MOB using quantitative real-time polymerase chain reaction.

RESULTS

The study showed that musk inhalation significantly reduced (p < 0.001) corticosterone level, immobility time, inflammatory cytokines, and oxidative stress markers in CUMS-exposed mice compared to the untreated CUMS group. Musk lessened CUMS-associated neuronal alterations in the MOB and significantly reduced apoptosis and enhanced neural cell proliferation (p < 0.001) comparable to fluoxetine. Musk significantly enhanced the level of antioxidants in the serum and significantly reduced inflammatory cytokines. The anti-inflammatory and antioxidant activity of musk and its constituents seemed to be behind its neuroprotective effect observed in this study.

CONCLUSION

Musk effectively ameliorated the chronic stress-induced behavioral, biochemical, and neuronal structural changes in MOB mostly through its antioxidant and anti-inflammatory effect.

Characterization of pharmaco-EEG fingerprint and sleep-wake profiles of Lavandula angustifolia Mill. essential oil inhalation and diazepam administration in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Lavandula angustifolia Mill. Essential oil (Lavender EO) has a long history of medicinal use and is particularly claimed to possess anxiolytic and sedative properties. Lavender EO aromatherapy has been used to reduce distress and improve insomnia naturally. Increasing evidence appeared to show similarities between the effects of lavender EO and the anxiolytic drugs, benzodiazepines. However, its effects on sleep-wake and electrical brain patterns in comparison to that of the standard anxiolytic, diazepam, remained to be explored.

AIM OF THE STUDY

The aim of this work was to investigate electroencephalography (EEG) profiles and sleep-pattern elicited by lavender EO inhalation compared to that of diazepam, a standard anxiolytic drug in in vivo rat model.

MATERIALS AND METHODS

Adult male Wistar rats were anesthetized for electrode implantation on the frontal and parietal skulls. EEG signals were recorded for 180 min following intraperitoneal injection of diazepam (10 mg/kg) or during continuous inhalation of lavender EO (200 μL) or distilled water (control). Fast Fourier transform was used for the analyses of EEG power spectra and sleep-wake parameters.

RESULTS

During a 30-60 min period, diazepam and lavender EO significantly increased frontal powers of 0.78-45.31 and 7.03-18.36 Hz, respectively. Both treatments also increased parietal powers with lower magnitudes of significant change. Significant increases in some frequency ranges remained until a 60-90 min period. Sleep-wake analyses also revealed that diazepam significantly reduced time spent in wake, increased time spent in non-rapid eye movement (NREM), increased episode duration of NREM, decreased numbers of wake episode and decreased rapid eye movement (REM) sleep latency. On the other hand, lavender EO only significantly decreased wake episodes and latency to REM sleep. Lavender EO inhalation reduced numbers of wake episode but maintain normal time spent in wake, NREM and REM sleeps.

CONCLUSIONS

These findings might suggest beneficial and distinct anxiolytic-like effects of lavender EO for sleep enhancing purposes.

Anxiolytic Effect of Two Tobacco Essential Oils (Nicotiana tabacum Linn.) on Mice

Tobacco (Nicotiana tabacum Linn.) is a famous traditional herb used in folk medicine. The essential oils of tobacco have been demonstrated in modern studies to possess antioxidant, anti-inflammatory, and neuroprotective properties, while its anxiolytic effect has not been reported. The purpose of this study was to evaluate the anxiolytic effect of Yunnan tobacco essential oil (YTO) and Zimbabwe tobacco essential oil (ZTO) on mice. The constituents of YTO and ZTO were analyzed by GC/MS. The anxiolytic effect of YTO and ZTO (0.1%, 1%, and 10%, v/v) on male ICR mice was evaluated in the light-dark box test (LDB) and the elevated plus maze test (EPM) test via inhalation and transdermal administration. After the behavioral tests, salivary corticosterone levels in mice were measured. The behavioral analysis showed that the administration of both YTO and ZTO elevated the time that the mice spent in the light chamber in the LDB test compared to the untreated control. In the EPM test, YTO and ZTO increased the time spent in open arms and the number of entries into the open arms. In addition, both YTO and ZTO significantly decreased salivary corticosterone levels in mice (p ≤ 0.001). In summary, our results demonstrated that inhalation and transdermal administration of both YTO and ZTO showed anxiolytic effect on male ICR mice.

Activity of Selected Group of Monoterpenes in Alzheimer's Disease Symptoms in Experimental Model Studies-A Non-Systematic Review

Alzheimer's disease (AD) is the leading cause of dementia and cognitive function impairment. The multi-faced character of AD requires new drug solutions based on substances that incorporate a wide range of activities. Antioxidants, AChE/BChE inhibitors, BACE1, or anti-amyloid platelet aggregation substances are most desirable because they improve cognition with minimal side effects. Plant secondary metabolites, used in traditional medicine and pharmacy, are promising. Among these are the monoterpenes-low-molecular compounds with anti-inflammatory, antioxidant, enzyme inhibitory, analgesic, sedative, as well as other biological properties. The presented review focuses on the pathophysiology of AD and a selected group of anti-neurodegenerative monoterpenes and monoterpenoids for which possible mechanisms of action have been explained. The main body of the article focuses on monoterpenes that have shown improved memory and learning, anxiolytic and sleep-regulating effects as determined by in vitro and in silico tests-followed by validation in in vivo models.

Involvement of dopamine D2 and glutamate NMDA receptors in the antidepressant-like effect of amantadine in mice

The present study investigated the pharmacological mechanisms of the antidepressant-like effects of amantadine in mice and their influence on hippocampal neurogenesis. To improve the translational validity of preclinical results, reproducibility across laboratories and replication in other animal models and species are crucial. Single amantadine administration at doses of 50 and 75 mg/kg resulted in antidepressant-like effects in mice in the tail suspension test (TST), reflected by an increase in immobility time. The effects of amantadine were seen at doses that did not alter locomotor activity. The tyrosine hydroxylase inhibitor α-methyl-ρ-tyrosine did not influence the anti-immobility effect of amantadine in the TST. Pretreatment with the α₁ adrenergic receptor antagonist prazosin, β adrenergic receptor antagonist propranolol, α₂ adrenergic receptor antagonist yohimbine, and α₂ adrenergic receptor agonist clonidine did not alter the antidepressant-like effect of amantadine. However, amantadine's effect was blocked by the dopamine D₂ receptor antagonist haloperidol and glutamate receptor agonist N-methyl-D-aspartate (NMDA). Repeated amantadine administration (50 mg/kg) also exerted an antidepressant-like effect, paralleled by an increase in hippocampal neurogenesis. The present results demonstrate that the antidepressant-like effects of amantadine may be mediated by its actions on D₂ and NMDA receptors and likely involve hippocampal neurogenesis.

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.

Therapeutic Effect and Mechanisms of Essential Oils in Mood Disorders: Interaction between the Nervous and Respiratory Systems

Essential oils (EOs) are extracted from plants and contain active components with therapeutic effects. Evidence shows that various types of EOs have a wide range of health benefits. In our previous studies, the potential of lavender EO for prevention and even treatment of depression and anxiety symptoms was demonstrated. The favourable outcomes may be due to multiple mechanisms, including the regulation of monoamine level, the induction of neurotrophic factor expression, the regulation of the endocrine system and the promotion of neurogenesis. The molecules of EOs may reach the brain and exert an effect through two distinctive pathways, namely, the olfactory system and the respiratory system. After inhalation, the molecules of the EOs would either act directly on the olfactory mucosa or pass into the respiratory tract. These two delivery pathways suggest different underlying mechanisms of action. Different sets of responses would be triggered, such as increased neurogenesis, regulation of hormonal levels, activation of different brain regions, and alteration in blood biochemistry, which would ultimately affect both mood and emotion. In this review, we will discuss the clinical effects of EOs on mood regulation and emotional disturbances as well as the cellular and molecular mechanisms of action. Emphasis will be put on the interaction between the respiratory and central nervous system and the involved potential mechanisms. Further evidence is needed to support the use of EOs in the clinical treatment of mood disturbances. Exploration of the underlying mechanisms may provide insight into the future therapeutic use of EO components treatment of psychiatric and physical symptoms.

Essential Oils: Pharmaceutical Applications and Encapsulation Strategies into Lipid-Based Delivery Systems

Essential oils are being studied for more than 60 years, but a growing interest has emerged in the recent decades due to a desire for a rediscovery of natural remedies. Essential oils are known for millennia and, already in prehistoric times, they were used for medicinal and ritual purposes due to their therapeutic properties. Using a variety of methods refined over the centuries, essential oils are extracted from plant raw materials: the choice of the extraction method is decisive, since it determines the type, quantity, and stereochemical structure of the essential oil molecules. To these components belong all properties that make essential oils so interesting for pharmaceutical uses; the most investigated ones are antioxidant, anti-inflammatory, antimicrobial, wound-healing, and anxiolytic activities. However, the main limitations to their use are their hydrophobicity, instability, high volatility, and risk of toxicity. A successful strategy to overcome these limitations is the encapsulation within delivery systems, which enable the increase of essential oils bioavailability and improve their chemical stability, while reducing their volatility and toxicity. Among all the suitable platforms, our review focused on the lipid-based ones, in particular micro- and nanoemulsions, liposomes, solid lipid nanoparticles, and nanostructured lipid carriers.

Effect of aromatherapy on preoperative anxiety in adult patients: A meta-analysis of randomized controlled trials

BACKGROUND

and purpose: Preoperative anxiety is an important factor for postoperative complications, and many patients are using aromatherapy to relieve preoperative anxiety. This study aimed to evaluate the effect of aromatherapy on preoperative anxiety in adult patients.

METHODS

An electronic search of six databases (Cochrane Library, PubMed, Embase, CINAHL, CNKI, and WanFang Data) was conducted for full-text publications of trials published from the inception of the databases to February 20, 2020. All randomized controlled trials (RCTs) where aromatherapy was used for treatment of preoperative anxiety were included. Interventions included all types of aromatherapy compared to standard care or placebo. The primary outcome was self-rated anxiety and the secondary outcome was adverse effect. Two researchers independently screened and extracted relevant data. A random-effects model was utilized to calculate the effect size as mean difference (MD).

RESULTS

Our search retrieved 347 records. Thirteen trials were included for qualitative analysis, of which ten RCTs with 750 patients were included for meta-analysis. Most studies had a high or unclear selection and performance bias. Overall, aromatherapy was found to decrease preoperative anxiety significantly compared to the control group (MD = -3.95, 95%CI [-6.36, -1.53], P = 0.001). According to subgroup analysis, most subgroups showed a significant effect of aromatherapy on preoperative anxiety, except for the no treatment subgroup (MD: 5.40, 95%CI: 7.76 to 0.71) and female subgroup (MD: 3.96, 95%CI: 9.19 to 1.27).

CONCLUSION

Aromatherapy may be an effective complementary treatment for preoperative anxiety. Nevertheless, due to methodological limitations of the included trials, further studies with strict control of the research design are required for firm recommendations.

Pharmacological basis of the anxiolytic and antidepressant properties of Silexan®, an essential oil from the flowers of lavender

Silexan®, a proprietary essential oil manufactured by steam distillation from Lavandula angustifolia flowers showed pronounced anxiolytic effects in patients with subthreshold anxiety disorders and was also efficacious in patients with Generalized Anxiety disorder (GAD). Moreover, evidences for antidepressant-like properties of Silexan® have been observed in anxious patients suffering from comorbid depressive symptoms and in patients with mixed anxiety-depression disorder (ICD-10 F41.2). In accordance with the clinical data Silexan® is active in several behavioral models in rodents at rather low concentrations indicating potent anxiolytic and antidepressive properties. As possible mechanism of action a moderate inhibition of voltage dependent calcium channels (VDCC) has been found showing some similarities to the anxiolytic drug pregabalin. However, while pregabalin mainly inhibits P/Q-type channels by binding to a modulatory subunit, Silexan® moderately inhibits mainly T-type and N-type channels and to some extent P/Q-type channels. Unlike pregabalin Silexan® is free of hypnotic or sedative side effects and seems to be devoid of any abuse potential. With respect to its specific antidepressant like properties Silexan® improves several aspects of neuroplasticity which seems to be the common final pathway of all antidepressant drugs. As a potential mechanism of its effects on neuroplasticity an activation of the transcription factor CREB via activation of intracellular signaling kinases like PKA and MAPK has been found. Since the concentrations of Silexan® needed to inhibit VDCC function and to improve neuroplasticity are quite similar, the effects of Silexan® on PKA or MAPK could constitute a common intracellular signaling cascade leading to VDCC modulation as well as CREB activation and improved neuroplasticity.

The Therapeutic Prospects of Naturally Occurring and Synthetic Indole Alkaloids for Depression and Anxiety Disorders

Depression and anxiety are the most common disorders among all age groups. Several antidepressant drugs including benzodiazepine, antidepressant tricyclics, azapirone, noradrenaline reuptake inhibitors, serotonin selective reuptake inhibitors, serotonin, noradrenaline reuptake inhibitors, and monoamine oxidase inhibitors have been used to treat these psychiatric disorders. However, these antidepressants are generally synthetic agents and can cause a wide range of side effects. The potential efficacy of plant-derived alkaloids has been reviewed against various neurodegenerative diseases including Alzheimer's disease, Huntington disease, Parkinson's disease, schizophrenia, and epilepsy. However, data correlating the indole alkaloids and antidepressant activity are limited. Natural products, especially plants and the marine environment, are rich sources of potential new drugs. Plants possess a variety of indole alkaloids, and compounds that have an indole moiety are related to serotonin, which is a neurotransmitter that regulates brain function and cognition, which in turn alleviates anxiety, and ensures a good mood and happiness. The present review is a summary of the bioactive compounds from plants and marine sources that contain the indole moiety, which can serve as potent antidepressants. The prospects of naturally occurring as well as synthetic indole alkaloids for the amelioration of anxiety and depression-related disorders, structure-activity relationship, and their therapeutic prospects have been discussed.

Chemical Investigation and Screening of Anti-Proliferative Activity on Human Cell Lines of Pure and Nano-Formulated Lavandin Essential Oil

Lavandin essential oil (LEO), a natural sterile hybrid obtained by crossbreeding L. angustifolia × L. latifolia, is mainly composed by active components belonging to the family of terpenes endowed with relevant anti-proliferative activity, which can be enhanced by proper application of nanotechnology. In particular, this study reports the chemical characterization and the screening of the anti-proliferative activity on different human cell lines of pure and nano-formulated lavandin essential oil (EO). LEO and its formulation (NanoLEO) were analyzed by HS/GC-MS (Headspace/Gas Chromatography-Mass Spectrometry) to describe and compare their chemical volatile composition. The most abundant compounds were linalool and 1,8-cineole (LEO: 28.6%; 27.4%) (NanoLEO: 60.4%; 12.6%) followed by α-pinene (LEO: 9.6%; NanoLEO: 4.5%), camphor (LEO: 6.5%; NanoLEO: 7.0%) and linalyl acetate (LEO: 6.5%; NanoLEO: 3.6%). The cytotoxic effects of LEO and NanoLEO were investigated on human neuroblastoma cells (SHSY5Y), human breast adenocarcinoma cells (MCF-7), human lymphoblastic leukemia cells (CCRF CEM), human colorectal adenocarcinoma cells (Caco-2) and one normal breast epithelial cell (MCF10A) by the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide)-assay. Caco-2, MCF7 and MCF10A normal cells resulted more resistant to the treatment with LEO, while CCRF-CEM and SHSY5Y cells were more sensitive. The antiproliferative effect of LEO resulted amplified when the essential oil was supplied as nanoformulation, mainly in Caco-2 cells. Scanning and transmission electron microscopy investigations were carried out on Caco-2 cells to outline at ultrastructural level possible affections induced by LEO and NanoLEO treatments.

Anti-psoriatic effect of Lavandula angustifolia essential oil and its major components linalool and linalyl acetate

ETHNO-PHARMACOLOGICAL RELEVANCE

Lavender oil (LO) is an aromatic/essential oil extracted from Lavandula angustifolia and traditionally used as an aromatherapy massage oil due to its anti-inflammatory and wound healing property and also for providing the relief in other skin conditions such as psoriasis, dermatitis and eczema. However, LO has not been evaluated scientifically for psoriasis like skin inflammation.

AIM OF THE STUDY

This study was aimed to investigate the LO and its major components linalool (L) and linalyl acetate (LA) against psoriasis like skin inflammation.

MATERIALS AND METHODS

Anti-psoriatic activity was done using Imiquimod (IMQ) induced psoriasis like skin inflammation in BALB/c mice. Assessment of anti-psoriatic effect of LO, L and LA was done on the basis of change in ear thickness, psoriasis area severity index (PASI) scoring at alternative day, CosCam scoring using skin analyzer equipped with SkinSys software, biochemical, immunohistochemical and histological investigations. Level of effectiveness against psoriasis was investigated by percent reduction in PASI scores, CosCam scores and level of Th-1 and Th-17 cell expressing cytokines, as compared to the diseased mice.

RESULTS

Topical application of LO 10% showed 73.67% recovery in PASI and 87% in Th-17 cell-specific cytokines towards normal as compared to disease group. L and LA were identified as the major components of LO and favoured ligands for selected psoriasis targets. At 2% topical dose, L and LA showed 64% and 47.61% recovery in PASI scores, respectively. Both, L and LA showed significant recovery in Th-1 specific TNF-α and IL-1β however, only L showed significant recovery of Th-17 cytokines (IL-17 and IL-22). In contrast to LA (which restored granulosis), L restored epidermal hyperplasia and parakeratosis toward the normal condition. On the other hand, L also reduced the expression of NF-κβ, ccr6 and IL-17, while LA reduced the expression of NF-κβ only. At 10% topical dose, LO was observed to be slight irritant while at 2% topical dose, L and LA were found non-irritant to the skin.

CONCLUSION

This study proves the effectiveness of LO and its major phytoconstituents linalool and linalyl acetate against IMQ induced psoriasis like skin inflammation and provides the scientific evidence for topical use of lavender oil.

Aromatherapy improves cognitive dysfunction in senescence-accelerated mouse prone 8 by reducing the level of amyloid beta and tau phosphorylation

Alzheimer’s disease (AD) is a progressive neurodegenerative disease and is known to be the most common cause of dementia. We previously described the benefits of aromatherapy on the cognitive function of patients with AD utilizing various aromatic essential oils; however, its mechanism of action remains poorly understood. Consequently, in the present study, this mechanism was thoroughly evaluated employing a dementia mice model, specifically the senescence-accelerated mouse prone 8. The mice were exposed to a mixture of lemon and rosemary oil at nighttime as well as to a mixture of lavender and orange oil in the daytime for 2 months. The cognitive function of the mice was assessed before and after treatment with the aromatic essential oils using the Y-maze test. Moreover, the brain levels of amyloid beta (Aβ), abnormally phosphorylated tau, and brain-derived neurotrophic factor (BDNF) were measured following treatment. The benefits of aromatherapy on the cognitive function in mice were confirmed. It was also established that the brain levels of Aβ and abnormally phosphorylated tau were considerably lower in the aromatherapy group, while the levels of BDNF were marginally higher. These results suggest that aromatherapy employing these aromatic essential oils is beneficial for the prevention and treatment of AD.

Inhaled Lavandula angustifolia essential oil enhances extinction learning and inhibits memory updating in mice submitted to the contextual fear conditioning

ETHNOPHARMACOLOGICAL RELEVANCE

Lavender (Lavandula angustifolia) essential oil (EO) has a long history of use in emotional illness, including anxiety disorders. Cognitive mechanisms of learning and memory play a pivotal role in the etiology and maintenance of anxiety since exposure to cues related to aversive situations induces high arousal and anticipatory anxiety. Memory become labile after its reactivation and can be modulated by reconsolidation or extinction. Inhibition of memory reconsolidation or facilitation of memory extinction may be effective in preventing or minimizing the effect of contextual cues on anticipatory anxiety.

AIM OF THE STUDY

We investigated the effect of Lavandula angustifolia EO in the memory updating of conditioned contextual fear.

MATERIALS AND METHODS

Adult male C57Bl6 mice were submitted to fear conditioning. Two days after conditioning the mice underwent a reactivation session in a hybrid context and were then immediately exposed to vaporized water or essential oil at concentrations of 1%, 2.5% or 5% for 3 h. Two days later, the mice were tested in the original or an altered context and their freezing behavior was measured. In addition, mice were subjected to a fear memory recovery protocol followed by a reinstatement session.

RESULTS

In the contextual fear test, 1% essential oil, but not 2.5% or 5%, reduced the freezing behavior response, whereas after a reinstatement session, exposure to 1% essential oil increased the freezing behavior response.

CONCLUSIONS

These results suggest that Lavandula angustifolia essential oil enhances memory extinction and, consequently, inhibits memory updating.

Anxiety Therapeutic Interventions of β-Caryophyllene: A Laboratory-Based Study

The bicyclic sesquiterpene β-caryophyllene (BCP) has diverse biological activities, including antioxidant, anti-inflammatory, antidiabetic, and analgesic effects. This study evaluates anxiolytic, toxicity, and antioxidant effects of BCP using in vitro and in vivo test models. The anxiolytic effects were tested in Swiss albino mice ( Mus musculus) by applying the elevated plus-maze, rota-rod, light and dark, and hiding sphere models, while the toxicity was evaluated by brine shrimp ( Artemia salina) lethality bioassay. Additionally, the antioxidant capacity was tested by using 2,2-diphenyl-1-picrylhydrazyl radical, 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid hydroxyl radical scavenging, and the Saccharomyces cerevisiae test model. The results suggest that BCP exerted a dose-dependent anxiolytic-like effect on the experimental animals. It did not show toxicity in A. salina at 24 hours. BCP showed a concentration-dependent free-radical-scavenging capacity, similar to the standard antioxidant Trolox. It also showed protective and repair capacities against hydrogen peroxide-induced damaging effects in isogenic and wild-type S. cerevisiae strains. Taken together, BCP exerted antioxidant and protective effects, which can be targeted to treat neurological diseases and disorders such as anxiety.

Similarities and dissimilarities in the effects of benzodiazepines and specific serotonin reuptake inhibitors (SSRIs) in the defensive marble burying test: A systematic review and meta-analysis

One problem areas of animal models and tests for neuropsychiatric disorders is unclear reproducibility, including both internal and external validity. One way to examine external validity is with systematic reviews and meta-analyses, a standard practice in clinical research that is relatively neglected in preclinical research. Considering the need to evaluate the validity and reproducibility of frequently used animal models, this study presents a meta-analysis of the effects of prototypic benzodiazepines and specific serotonin reuptake inhibitors (SSRIs) in the mouse defensive marble burying test (MBT). These drug groups were selected because although they differ in their biological targets as well as in their clinical use, they are both commonly used for the treatment of anxiety disorders. A PubMed literature search was performed to identify studies that examined the effects of benzodiazepines (diazepam, alprazolam, chlordiazepoxide, clonazepam) or SSRIs (fluoxetine, citalopram, escitalopram, fluvoxamine, paroxetine) in the MBT in mice. For benzodiazepines, 73 experiments were included. Benzodiazepines effect size was 2.04 and Q statistics was 1959 with a significant correlation between dose and effect size (r = 0.31, p = 0.007). For SSRIs we identified 47 experiments. Effect size of SSRIs was 2.24 and Q statistics was 493.38. No correlation was found between dose and effect size (r = 0.23, p = 0.12). The current results support the external validity of the defensive marble burying test as a screening test for anxiolytic effects. However, these results indicate that significant attention should be given to the administration schedules of benzodiazepines and SSRIs.

Can lavender oil inhalation help to overcome dental anxiety and pain in children? A randomized clinical trial

Aromatherapy with essential oils can be used to relieve children. The aim of this study was to evaluate the correlations between psychological and physiologic findings after lavender oil inhalation among children assigned to undergo tooth extraction. A total of 126 children aged between 6 and 12 years were enrolled in the study. The groups were randomly divided into control and lavender groups. The lavender group inhaled 100% lavender oil for 3 min before the interventions, the control group received no prior application. Psychological assessments were made using face image scale (FIS), Face, Legs, Activity, Cry, Consolability (FLACC) and Wong-Baker pain rating scale (WBS). Physiologic changes were assessed using vital signs evaluations. All parameters were noted prior to applications, after inhalation, anesthesia injection, and tooth extraction. The lavender group showed significant lower anxiety and pain scores after tooth extraction (p < 0.05). Significantly lower levels of blood pressures and a significant pulse rate drop were found after inhalation in the lavender group. A statistically significant increase in heart rate was observed after anesthesia injection and tooth extraction in the control group (p < 0.05).Conclusion: Lavender oil can be preferred as a treatment of choice in routine pediatric dentistry.Trial registration number: NCT04115891 (Lavender Oil Inhalation Help to Overcome Dental Anxiety Among Children)What is Known:• Dental anxiety is the most common factor that causes children to have difficulty with the dentist and their parents during treatment.• Aromatherapy with essential oils can be used to relieve children.What is New:• Aromatherapy with lavender oil relieves the child by reducing the level of anxiety and facilitates dental treatment.• During surgical procedures such as local anesthesia and tooth extraction, lavender oil inhalation decreases pain levels of children.

Role of 5-HT1A Receptor in the Anxiolytic-Relaxant Effects of Bergamot Essential Oil in Rodent

The essential oil obtained by the fresh fruit of Citrus bergamia Risso et Poiteau is used worldwide in aromatherapy to reduce pain, facilitate sleep induction, and/or minimize the effects of stress-induced anxiety. Preclinical pharmacological data demonstrate that bergamot essential oil (BEO) modulates specific neurotransmissions and shows an anxiolytic-relaxant effect not superimposable to that of the benzodiazepine diazepam, suggesting that neurotransmissions, other than GABAergic, could be involved. Several studies on essential oils indicate a role for serotonergic (5-HT) neurotransmission in anxiety. Interestingly, among serotonergic receptors, the 5-HT1A subtype seems to play a key role in the control of anxiety. Here, we report that modulation of the 5-HT1A receptor by selective agonist ((±)8-OH-DPAT) or antagonist (WAY-100635) may influence some of the anxiolytic-relaxant effects of BEO in Open Field and Elevated Plus Maze tests.

Neuropharmacological Characterization of Dioclea altissima Seed Lectin (DAL) in Mice: Evidence of Anxiolytic-like Effect Mediated by Serotonergic, GABAergic Receptors and NO Pathway

BACKGROUND

Plant lectins have shown promising biological activities in the central nervous system (CNS).

OBJECTIVE

This study evaluated the effect of DAL, a lectin isolated from the seeds of the Dioclea altissima species, having binding affinity to D-glucose or D-mannose residues, on mice behavior.

METHODS

Mice (n=6/group) were treated (i.p.) with DAL (0.25, 0.5 or 1 mg/kg) or vehicle and subjected to several tests (open field/OFT, marble-burying/MBT, hole-board/HBT, elevated plus maze/PMT, tail suspension/ TST, forced swimming/FST or rotarod/RRT). Pizotifen, cyproheptadine, flumazenil, L-NAME, 7-NI, Larginine or yohimbine were administered 15 min before DAL (0.5 mg/kg) and the animals were evaluated on PMT. It was also verified whether the DAL effect depended on its structural integrity and ability to interact with carbohydrates.

RESULTS

The results showed there were no neurobehavioral changes in the mice at the RRT, FST and locomotion in the OFT. DAL (0.25, 0.5 or 1 mg/kg) increased the behavior of grooming and rearing in the OFT, head dips in the HBT, pedalling in the TST and decreased the number of marbles hidden in the MBT. In the PMT, DAL (0.25, 0.5 and 1 mg/kg) and Diazepam increased the frequency of entries in the open arms and the time of permanence in the open arms without affecting the locomotor activity. The effect of DAL was dependent on carbohydrate interaction and protein structure integrity and it prevented by pizotifen, cyproheptadine, flumazenil, L-NAME and 7-NI, but not by L-arginine or yohimbine.

CONCLUSION

DAL was found to have an anxiolytic-like effect mediated by the 5-HT and GABAergic receptors and NO pathway.

Behavioral and Neurobiological Convergence of Odor, Mood and Emotion: A Review

The affective state is the combination of emotion and mood, with mood reflecting a running average of sequential emotional events together with an underlying internal affective state. There is now extensive evidence that odors can overtly or subliminally modulate mood and emotion. Relying primarily on neurobiological literature, here we review what is known about how odors can affect emotions/moods and how emotions/moods may affect odor perception. We take the approach that form can provide insight into function by reviewing major brain regions and neural circuits underlying emotion and mood, and then reviewing the olfactory pathway in the context of that emotion/mood network. We highlight the extensive neuroanatomical opportunities for odor-emotion/mood convergence, as well as functional data demonstrating reciprocal interactions between these processes. Finally, we explore how the odor- emotion/mood interplay is, or could be, used in medical and/or commercial applications.

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.

Ocimum basilicum (Basil) Modulates Apoptosis and Neurogenesis in Olfactory Pulp of Mice Exposed to Chronic Unpredictable Mild Stress

BACKGROUND

Ocimum basilicum (O. basilicum) was described to have antidepressant and anxiolytic activities. Although the relationship between the main olfactory bulb (MOB) and depression was recently reported, the chronic stress-induced dysfunction of the MOB is not clearly described.

OBJECTIVES

This study aimed to assess the efficacy of inhalation of O. basilicum essential oils in improving chronic unpredictable mild stress (CUMS)-induced changes in MOB of mice and understand the mechanism underlying such effect.

MATERIALS AND METHODS

Adult male mice (n=40) were assigned into four groups included the control, CUMS-exposed, CUMS + fluoxetine (FLU), CUMS + O. basilicum. Behavioral changes, serum corticosterone level, and gene expression of GFAP, Ki 67, and caspase-3 were assessed using real-time PCR (RT-PCR). Histopathological and immunochemical examination of the MOB was performed.

RESULTS

FLU and O. basilicum significantly down-regulated (p = 0.002, p<0.001) caspase-3 gene expression indicating reduced apoptosis and up-regulated (p = 0.002, p < 0.001) Ki67 gene expression indicating enhanced neurogenesis in MOB, respectively. FLU and O. basilicum-treated mice markedly improved MOB mitral cell layer distortion and shrinkage induced by CUMS.

CONCLUSION

O. basilicum relieved both biochemically and histopathological chronic stress-induced changes in the main olfactory bulb possibly through up-regulation of gene expression of GFAP and Ki67 and down-regulation of caspase-3 in the MOB.

Anxiolytic Effect of Essential Oils and Their Constituents: A Review

Essential oils are usually used in aromatherapy to alleviate anxiety symptoms. In comparison to traditional drugs, essential oils have fewer side effects and more diversified application ways, including inhalation. This review provides a comprehensive overview of studies on anxiolytic effects of essential oils in preclinical and clinical trials. Most of the essential oils used in clinical studies have been proven to be anxiolytic in animal models. Inhalation and oral administration were two common methods for essential oil administration in preclinical and clinical trials. Massage was only used in the clinical trials, while intraperitoneal injection was only used in the preclinical trails. In addition to essential oils that are commonly used in aromatherapy, essential oils from many folk medicinal plants have also been reported to be anxiolytic. More than 20 compounds derived from essential oils have shown an anxiolytic effect in rodents, while two-thirds of them are alcohols and terpenes. Monoamine neurotransmitters, amino acid neurotransmitters, and the hypothalamic-pituitary-adrenal axis are thought to play important roles in the anxiolytic effects of essential oils.

Effect of one time coffee fragrance inhalation on working memory, mood, and salivary cortisol level in healthy young volunteers: a randomized placebo controlled trial

Background

Olfactory system regulates the brain which controls emotional memory. Coffee is one of the most consumed beverages in the world. Drinking coffee shows beneficial effects for mood, memory, and psychomotor performance. This work aimed to determine the effects of inhaling coffee fragrance on memory, mood, and salivary cortisol level in healthy young volunteers.

Methods

Eighty young males and females, aged between 18–22 years old, were randomly assigned into two groups: a placebo group inhaling scent from carbon powder and a coffee fragrance group inhaling coffee fragrance. Subjects were assigned to inhale either placebo or coffee fragrance for five minutes. Before and after inhalation period, the clinical assessments were assigned to each subject including computerized assessment battery test for cognitive performance, and self-related visual analogue mood scales for evaluation of mood score. The salivary cortisol level was assessed with cortisol ELISA kit. In addition, the blood pressure and heart rate were also evaluated.

Results

Inhalation of coffee fragrance enhanced cognitive parameters, including continuity of attention, quality of memory, and speed of memory, and also increased the mood score of alertness. However, there were no significant changes in salivary cortisol level, blood pressure, and heart rate between pre-and post-inhalation.

Conclusion

One time of coffee fragrance inhalation may enhance working memory and stimulates alertness. However, inhaling coffee fragrance does not reduce stress or modulate autonomic response to stress.