Lemon oil vapor causes an anti-stress effect via modulating the 5-HT and DA activities in mice

Inhaled essential oil from Chamaecyparis obtuse ameliorates the impairments of cognitive function induced by injection of β-amyloid in rats

CONTEXT

Chamaecyparis obtusa Sieb. & Zucc., Endlicher (Cupressaceae) forest bathing or aromatherapy has been shown in various studies to have biological functions such as anticancer, antiallergies, antiinflammatory, and antioxidant activity. However, no reports exist on the pharmacological or biological activities of the essential oil of C. obtusa (EOCO) or its effects on central nervous system.

OBJECTIVE

The aggregation and formation of β-amyloid peptides (Aβ) into fibrils are central events in the pathogenesis of Alzheimer's disease (AD), and overproduction and aggregation of Aβ into oligomers have been known to trigger neurotoxicity. In this study, we investigated the effects of inhaled EOCO on cognitive function and neuronal apoptosis in rats intrahippocampally injected with Aβ.

MATERIALS AND METHODS

To model AD, 4 μg of aggregated Aβ was injected into the hippocampus. To test the effects of EOCO, behavioral performance in the Morris water maze was tested 4 days after injection. After behavioral testing, brain sections were prepared for TTC staining and TUNEL assay.

RESULTS

Inhaled EOCO protected spatial learning and memory from the impairments induced by Aβ(1-40) injection. In addition, the behavioral deficits accompanying Aβ(1-40)-induced AD were attenuated by inhalation of EOCO. Furthermore, acetylcholinesterase (AChE) activity and neuronal apoptosis were significantly inhibited in rats treated with Aβ(1-40) and EOCO compared to rats treated only with Aβ(1-40).

DISCUSSION AND CONCLUSION

EOCO suppressed both AD-related neuronal cell apoptosis and AD-related dysfunction of the memory system. Thus, the results of this study support EOCO as a candidate drug for the treatment of AD.

Cutaneous magnetic stimulation reduces rat chronic pain via activation of the supra-spinal descending pathway

Recent studies have demonstrated that magnetic stimulation (MS) can induce cellular responses such as Ca(2+) influx into the cultured neurons and glia, leading to increased intracellular phosphorylation. We have demonstrated previously that MS reduces rat neuropathic pain associated with the prevention of neuronal degeneration. Thus, we aimed to elucidate the actions of MS in relation to modulation of spinal neuron-glia and the descending inhibitory system in chronic pain. The male SD rats intrathecally implanted with catheters were subjected to sciatic nerve ligation (CCI). MS is a low power apparatus characterized by two different frequencies, 2 KHz and 83 MHz. Rats were given MS to the skin (injured sciatic nerve) for 10 min from the seventh day after CCI. The paw withdrawal latency (PWL) evoked by thermal stimuli was measured for 14 days after CCI. Immunohistochemistry for Iba-1 or GFAP was performed after 4% paraformaldehyde fixation (microscopic analysis). We employed microdialysis for measuring CSF 5-HIAA as a reflection of 5-HT release by MS stimulation. Following CCI, rats showed a decrease in PWL after CCI, and the decrease continued until the 14th day. With MS treatment, the decrease in PWL was reduced during the 10-14 day after CCI. Injection of JNK-1 inhibitors on the 14th day antagonized the analgesic effect of MS. MS also eliminated the CCI-induced decrease in GFAP immunoreactivity. Moreover, MS evoked spinal 5-HT release reflected by increase in spinal 5-HIAA level. Thus, we demonstrate that a novel magnetic stimulator used cutaneously can ameliorate chronic pain by not only preventing abnormal spinal neuron-glia interaction, but also through the activation of the supra-spinal descending inhibitory system.

Evaluation of acute toxicity of a natural compound (+)-limonene epoxide and its anxiolytic-like action

The aim of the study is to determine the acute toxicity and anxiolytic-like effects of a mixture of cis and trans of (+)-limonene epoxide in animal models of anxiety. After acute treatment with (+)-limonene epoxide at doses of 25, 50 and 75 mg/kg (i.p.) no mortality was noted during 14 days of observation. In general, behavior, food and water consumption showed no significant changes. In open field test, (+)-limonene epoxide at doses of 25, 50 and 75 mg/kg, after intraperitoneal administration, significantly decreased the number of crossings, grooming and rearing (p<0.001). All these effects were reversed by the pre-treatment with flumazenil (25 mg/kg, i.p.), similar to those observed with diazepam used as a positive standard. In the elevated-plus-maze test, (+)-limonene epoxide increased the time of permanence and the number of entrances in the open arms. All these effects were reversed by flumazenil, an antagonist of benzodiazepine receptors. In addition, (+)-limonene epoxide (75 mg/kg) also produced a significant inhibition of the motor coordination (p<0.01), that was reversed by flumazenil. In conclusion, the present work evidenced sedative and anxiolytic-like effects of (+)-limonene epoxide, which might involve an action on benzodiazepine-type receptors. These results indicate that the properties of (+)-limonene epoxide should be more thoroughly examined in order to achieve newer tools for management and/or treatment of central nervous system diseases and anxiolytic-like effects. The LD50 obtained for the acute toxicity studies using intraperitoneal route of administration was 4.0 g/kg. These findings suggest that acute administration of the (+)-limonene epoxide exerts an anxiolytic-like effect on mice, and it could serve as a new approach for the treatment anxiety, since it practically does not produce toxic effects.

Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects

Tetrahydrocannabinol (THC) has been the primary focus of cannabis research since 1964, when Raphael Mechoulam isolated and synthesized it. More recently, the synergistic contributions of cannabidiol to cannabis pharmacology and analgesia have been scientifically demonstrated. Other phytocannabinoids, including tetrahydrocannabivarin, cannabigerol and cannabichromene, exert additional effects of therapeutic interest. Innovative conventional plant breeding has yielded cannabis chemotypes expressing high titres of each component for future study. This review will explore another echelon of phytotherapeutic agents, the cannabis terpenoids: limonene, myrcene, α-pinene, linalool, β-caryophyllene, caryophyllene oxide, nerolidol and phytol. Terpenoids share a precursor with phytocannabinoids, and are all flavour and fragrance components common to human diets that have been designated Generally Recognized as Safe by the US Food and Drug Administration and other regulatory agencies. Terpenoids are quite potent, and affect animal and even human behaviour when inhaled from ambient air at serum levels in the single digits ng·mL(-1) . They display unique therapeutic effects that may contribute meaningfully to the entourage effects of cannabis-based medicinal extracts. Particular focus will be placed on phytocannabinoid-terpenoid interactions that could produce synergy with respect to treatment of pain, inflammation, depression, anxiety, addiction, epilepsy, cancer, fungal and bacterial infections (including methicillin-resistant Staphylococcus aureus). Scientific evidence is presented for non-cannabinoid plant components as putative antidotes to intoxicating effects of THC that could increase its therapeutic index. Methods for investigating entourage effects in future experiments will be proposed. Phytocannabinoid-terpenoid synergy, if proven, increases the likelihood that an extensive pipeline of new therapeutic products is possible from this venerable plant. http://dx.doi.org/10.1111/bph.2011.163.issue-7.

Chlordiazepoxide and lavender oil alter unconditioned anxiety-induced c-fos expression in the rat brain

Lavender oil has a long history of use for treating anxiety, but only recent research has examined its effects using standard behavioural methods used to test novel drugs. The aim of this study was to investigate the effects of inhaled lavender oil on anxiety related behaviour of rats in the open field and to compare them with the effects of chlordiazepoxide (CDP), a typical anxiolytic drug. Additionally c-fos immunochemistry was used to investigate whether lavender oil produced the same pattern of c-fos expression as CDP in eight different brain areas associated with anxiety. As previously found, lavender oil showed anxiolytic properties in the open field similar to but not as extensive as those of CDP. Immunochemistry results indicated that exposure to the open field increased c-fos expression, while CDP reversed the effects of this behavioural stressor on c-fos expression in all brain regions examined except the central nucleus of the amygdala, where c-fos expression increased. Lavender oil had similar effects to CDP on the paraventricular nucleus of the hypothalamus, the dorsomedial hypothalamic nucleus and the central nucleus of the amygdala. These results strengthen the suggestion that inhaling lavender oil has anxiolytic behavioural effects, but they are weaker than the effects of benzodiazepines, and there is limited evidence that they are mediated by the same neural processes.

A review on the effects of aromatherapy for patients with depressive symptoms

PURPOSE

We reviewed studies from 2000 to 2008 on using essential oils for patients with depression or depressive symptoms and examined their clinical effects.

METHODS

The review was conducted among five electronic databases to identify all peer-reviewed journal papers that tested the effects of aromatherapy in the form of therapeutic massage for patients with depressive symptoms.

RESULTS

The results were based on six studies examining the effects of aromatherapy on depressive symptoms in patients with depression and cancer. Some studies showed positive effects of this intervention among these three groups of patients.

CONCLUSIONS

We recommend that aromatherapy could continue to be used as a complementary and alternative therapy for patients with depression and secondary depressive symptoms arising from various types of chronic medical conditions. More controlled studies with sound methodology should be conducted in the future to ascertain its clinical effects and the underlying psychobiologic mechanisms.

Protective essential oil attenuates influenza virus infection: an in vitro study in MDCK cells

Background

Influenza is a significant cause of morbidity and mortality. The recent pandemic of a novel H1N1 influenza virus has stressed the importance of the search for effective treatments for this disease. Essential oils from aromatic plants have been used for a wide variety of applications, such as personal hygiene, therapeutic massage and even medical practice. In this paper, we investigate the potential role of an essential oil in antiviral activity.

Methods

We studied a commercial essential oil blend, On Guard™, and evaluated its ability in modulating influenza virus, A/PR8/34 (PR8), infection in Madin-Darby canine kidney (MDCK) cells. Influenza virus was first incubated with the essential oil and infectivity in MDCK cells was quantified by fluorescent focus assay (FFA). In order to determine the mechanism of effects of essential oil in viral infection inhibition, we measured hemagglutination (HA) activity, binding and internalization of untreated and oil-treated virus in MDCK cells by flow cytometry and immunofluorescence microscopy. In addition, the effect of oil treatment on viral transcription and translation were assayed by relative end-point RT-PCR and western blot analysis.

Results

Influenza virus infectivity was suppressed by essential oil treatment in a dose-dependent manner; the number of nascent viral particles released from MDCK cells was reduced by 90% and by 40% when virus was treated with 1:4,000 and 1:6,000 dilutions of the oil, respectively. Oil treatment of the virus also decreased direct infection of the cells as the number of infected MDCK cells decreased by 90% and 45% when virus was treated with 1:2,000 and 1:3,000 dilutions of the oil, respectively. This was not due to a decrease in HA activity, as HA was preserved despite oil treatment. In addition, oil treatment did not affect virus binding or internalization in MDCK cells. These effects did not appear to be due to cytotoxicity of the oil as MDCK cell viability was only seen with concentrations of oil that were 2 to 6 times greater than the doses that inhibited viral infectivity. RT-PCR and western blotting demonstrated that oil treatment of the virus inhibited viral NP and NS1 protein, but not mRNA expression.

Conclusions

An essential oil blend significantly attenuates influenza virus PR8 infectivity in vitro without affecting viral binding or cellular internalization in MDCK cells. Oil treated virus continued to express viral mRNAs but had minimal expression of viral proteins, suggesting that the antiviral effect may be due to inhibition of viral protein translation.

Effects of Pleasant Ambient Fragrances on Dental Fear: Comparing Apples and Oranges

Previous studies showed that orange odor reduces the anticipatory anxiety and improves the mood of patients waiting for scheduled appointments in small dental practices. We replicated these previous studies in the setting of three large dental clinics. In addition, we investigated whether another pleasant fruity smell (apple odor) is similarly associated with reduced anxiety. We included 219 patients (117 males, 102 females) between the ages of 18 and 81 in this study. While they were waiting for dental treatment, the participants were either exposed to the ambient odor of orange (N = 81) or apple (N = 69), or they received no stimulation. State anxiety, mood, and perceived level of pain of the participants were assessed using questionnaires. Statistical analysis showed no significant difference between the responses of patients in each of the three experimental groups. We therefore conclude that orange and apple odors have no effect on the anticipatory anxiety or mood of patients waiting for scheduled appointments in large dental clinics.

Eficácia da aromaterapia na redução de níveis de estresse e ansiedade em alunos de graduação da área da saúde: estudo preliminar

Este estudo teve como objetivo verificar a eficácia de aromaterapia na diminuição de níveis de estresse e ansiedade (traço e estado) de alunos de graduação de cursos na área da saúde. Participaram do estudo 36 sujeitos, com idade entre 18 e 29 anos, que foram divididos entre os que receberam tratamento (grupo aroma, n=18) e o grupo controle (n=18). Os sujeitos foram avaliados quanto a níveis de estresse e ansiedade antes e após o período de intervenção, pela Lista de Sintomas de Estresse e pelo Inventário de Ansiedade Traço e Estado. O tratamento de aromaterapia consistiu em sete sessões (duas vezes por semana) de dez minutos de inalação com uma sinergia de óleos essenciais elaborada especificamente. Os escores de estresse e ansiedade antes e depois do tratamento foram comparados estatisticamente, com nível de significância de 5% (p<0,05). O grupo aroma apresentou redução significativa dos níveis de estresse (de 24%) e ansiedade (de 13% e 19%, p<0,05), enquanto no grupo controle houve uma diminuição significante, embora menor (de 11%), apenas no nível de estresse. A aromaterapia mostrou-se eficaz na redução dos níveis de estresse e ansiedade em estudantes da área da saúde. No entanto, ainda são necessários mais estudos para identificar as causas dos níveis medidos e, também, os mecanismos de ação dos óleos essenciais em sua redução.

Magnesium sulfate enhances exercise performance and manipulates dynamic changes in peripheral glucose utilization

The effect of magnesium supplementation on exercise performance remains controversial. In the present study, the effects of magnesium sulfate on exercise performance and blood glucose metabolism were examined. In order to provide a non-invasive measure of continuous exercise, we developed an auto-blood sampling system was coupled to a microdialysis analyzer to detect the dynamic changes in glucose metabolism in conscious and freely moving gerbils subjected to forced swimming. Gerbils were pretreated with saline or magnesium sulfate (90 mg kg(-1), ip) 30 min before exercise. The duration times were significantly increased by 71% in the magnesium sulfate-treated groups (p < 0.01) when compared with those in the control. Another group of gerbils were subjected to blood sampling assay. A catheter was implanted in the jugular vein of each gerbil for collecting blood samples by the computer-aided blood sampler. The basal levels of plasma glucose, lactate, and magnesium were 6,245 +/- 662, 1,067 +/- 309, and 590 +/- 50 microM, respectively, with no significant difference between groups. Plasma glucose, lactate, and magnesium levels increased to 134 and 204%, 369 and 220%, and 155 and 422% of basal levels during swimming in both the control and magnesium sulfate-treated groups, respectively (p < 0.05). Pretreatment with magnesium sulfate elevated glucose and magnesium levels to 175 and 302% of the basal levels (p < 0.05), respectively, whereas pretreatment with magnesium sulfate reduced the lactate levels 150% of the basal level (p < 0.05) during swimming. Furthermore, the magnesium levels increased to about 152-422% of basal levels during forced swimming and the recovery period (p < 0.05). The present study demonstrates that magnesium sulfate improved the duration time of forced swimming exercise. In addition, magnesium raised glucose levels and attenuated lactate levels during forced swimming. These results indicate that positive effects of magnesium supplementation may contribute to the enhancement of exercise performance in athletes.

Essential Oils and Anxiolytic Aromatherapy

A number of essential oils are currently in use as aromatherapy agents to relieve anxiety, stress, and depression. Popular anxiolytic oils include lavender (Lavandula angustifolia), rose (Rosa damascena), orange (Citrus sinensis), bergamot (Citrus aurantium), lemon (Citrus limon), sandalwood (Santalum album), clary sage (Salvia sclarea), Roman chamomile (Anthemis nobilis), and rose-scented geranium (Pelargonium spp.). This review discusses the chemical constituents and CNS effects of these aromatherapeutic essential oils, as well as recent studies on additional essential oils with anxiolytic activities.

Evaluation of the effect of topical application of lavender oil on autonomic nerve activity in dogs

OBJECTIVE

To investigate the effect of topical application of undiluted lavender oil on sympathovagal activity in dogs.

ANIMALS

5 healthy adult male Beagles.

PROCEDURES

An ambulatory ECG monitor (Holter recorder) was placed on each dog (day0), and 48-hour ECGs were recorded, beginning at 8:00 the next day (day 1). Lavender oil (0.18 mL) or saline (0.9% NaCl) solution (0.18 mL) was topically applied to the inner pinnas of both ears of all dogs at 8:30, 12:00, 15:30, and 19:00 on day 2. Each trial was duplicated in each dog, with an interval of 3 to 4 days between trials. Spectral indices of heart rate variability, power in the high-frequency range, and the ratio of low-frequency to high-frequency power were calculated as an indirect estimate of autonomic nerve activity.

RESULTS

When dogs were treated with lavender oil, the mean heart rate was significantly lower during the period of 19:00 to 22:30 on day 2, compared with the mean heart rate during the same period when dogs were treated with saline solution. On the other hand, high-frequency power during the period of 15:30 to 19:00 was significantly higher when dogs were treated with lavender oil, compared with the high-frequency power during the same period when dogs were treated with saline solution.

CONCLUSIONS AND CLINICAL RELEVANCE

The study revealed some evidence that topical application of lavender oil affected vagal activity in dogs. However, whether such an effect exists and whether lavender oil has a calming effect on dogs remains equivocal and requires additional investigation.

Inhaled linalool-induced sedation in mice

Linalool is a monoterpene often found as a major component of essential oils obtained from aromatic plant species, many of which are used in traditional medical systems as hypno-sedatives. Psychopharmacological evaluations of linalool (i.p. and i.c.v.) revealed marked sedative and anticonvulsant central effects in various mouse models. Considering this profile and alleged effects of inhaled lavender essential oil, the purpose of this study was to examine the sedative effects of inhaled linalool in mice. Mice were placed in an inhalation chamber during 60 min, in an atmosphere saturated with 1% or 3% linalool. Immediately after inhalation, animals were evaluated regarding locomotion, barbiturate-induced sleeping time, body temperature and motor coordination (rota-rod test). The 1% and 3% linalool increased (p<0.01) pentobarbital sleeping time and reduced (p<0.01) body temperature. The 3% linalool decreased (p<0.01) locomotion. Motor coordination was not affected. Hence, linalool inhaled for 1h seems to induce sedation without significant impairment in motor abilities, a side effect shared by most psycholeptic drugs.

Effects of borneol on the level of DNA damage induced in primary rat hepatocytes and testicular cells by hydrogen peroxide

The aim of this paper was to evaluate genotoxic effects of borneol and its ability to change DNA-damaging effects of H2O2 in rat hepatocytes and testicular cells. Both in vitro and ex vivo approaches were used in the case of hepatocytes. Testicular cells were tested only ex vivo, i.e. shortly after isolation from rats supplemented by borneol. Cytotoxicity of borneol increased in in vitro conditions in a concentration-dependent manner and it was associated with DNA-damaging effects at toxic concentrations. While non-toxic concentrations of borneol applied in vitro protected cells against H2O2-induced DNA damage and interfered only partly with rejoining of H2O2-induced DNA strand breaks, cytotoxic concentrations of borneol manifested synergy with H2O2, i.e. enhanced DNA-damaging effects of H2O2. On the other side, borneol given to rats in drinking water decreased the level of DNA damage induced by H2O2 in both hepatocytes and testicular cells. Our results show that though at higher concentrations (2-h treatment with >2 mM borneol >0.3084 mg/ml) borneol acts cytotoxically and genotoxically on primary hepatocytes cultured in vitro, if given to rats during 7 days in a daily concentration of 17.14 or 34.28 mg/kg it reduces genotoxicity of H2O2 in both hepatocytes and testicular cells.

Effects of environmental novelty on fear-related behavior and stress responses of rats to emotionally relevant odors

Although various emotional behaviors and activation of the hypothalamic-pituitary-adrenal (HPA) axis of rats are induced by the exposure of 2,5-dihydro-2,4,5-trimethylthiazoline: TMT, a component of fox odor, these odor-induced responses are influenced by the external environment. Our previous study demonstrated that exposure to green odor, a mixture of cis-3-hexenol and trans-2-hexenal, attenuated stress-induced elevation of the plasma ACTH level in rats. The present study investigated the effect of TMT or green odor on emotional behavior and the HPA axis stress response with or without the influence of environmental novelty. We exposed rats to TMT or green odor in "familiar" or "unfamiliar" environments and compared the various responses, including fear-related behaviors, non-defensive behaviors and plasma ACTH concentrations. TMT induced enhanced freezing behavior, reduced exploration behavior and elevations in plasma ACTH concentrations in two environmental conditions. Comparing TMT-induced responses in an unfamiliar environment with the familiar environment showed that environmental novelty enhanced TMT-induced fear-related behaviors and elevations of plasma ACTH concentrations. These results revealed that TMT causes fear and stress responses in both familiar and unfamiliar environments, although the novelty of an unfamiliar environment enhances these TMT-induced responses. On the other hand, green odor did not induce any responses in either environment. These findings indicate that odor-induced responses are influenced by the surrounding environment.

Antidepressant-like behavioral and neurochemical effects of the citrus-associated chemical apigenin

Apigenin is one type of bioflavonoid widely found in citrus fruits, which possesses a variety of pharmacological actions on the central nervous system. A previous study showed that acute intraperitoneal administration of apigenin had antidepressant-like effects in the forced swimming test (FST) in ddY mice. To better understand its pharmacological activity, we investigated the behavioral effects of chronic oral apigenin treatment in the FST in male ICR mice and male Wistar rats exposed to chronic mild stress (CMS). The effects of apigenin on central monoaminergic neurotransmitter systems, the hypothalamic-pituitary-adrenal (HPA) axis and platelet adenylyl cyclase activity were simultaneously examined in the CMS rats. Apigenin reduced immobility time in the mouse FST and reversed CMS-induced decrease in sucrose intake of rats. Apigenin also attenuated CMS-induced alterations in serotonin (5-HT), its metabolite 5-hydroxyindoleacetic acid (5-HIAA), dopamine (DA) levels and 5-HIAA/5-HT ratio in distinct rat brain regions. Moreover, apigenin reversed CMS-induced elevation in serum corticosterone concentrations and reduction in platelet adenylyl cyclase activity in rats. These results suggest that the antidepressant-like actions of oral apigenin treatment could be related to a combination of multiple biochemical effects, and might help to elucidate its mechanisms of action that are involved in normalization of stress-induced changes in brain monoamine levels, the HPA axis, and the platelet adenylyl cyclase activity.

Sex does matter: comments on the prevalence of male-only investigations of drug effects on rodent behaviour

Despite abundant evidence of sex differences in the effects of drugs on nonsexual behaviour in rats and mice, most researchers continue to investigate male animals exclusively. This was evident from a survey of all relevant research reports published during the period February 2005-September 2006 (inclusive) in recent issues of five representative behavioural pharmacological journals. Reasons for excluding female animals from most studies are discussed along with attempts to justify the use of either male or female animals only, and the value of including both sexes (especially when a drug effect is poorly understood). Although there are other factors that can influence the effects of drugs, such as strain, age and social density, the sex of experimental animals is the easiest to control and thus is well suited to inclusion in pharmacological investigations. It is accordingly suggested that, as has been recommended many times in the past, animals' sex should play a more important part in future research than is still currently the case.

Anxiolytic effects of lavender oil inhalation on open-field behaviour in rats

To establish a valid animal model of the effects of olfactory stimuli on anxiety, a series of experiments was conducted using rats in an open-field test. Throughout, effects of lavender oil were compared with the effects of chlordiazepoxide (CDP), as a reference anxiolytic with well-known effects on open-field behaviour. Rats were exposed to lavender oil (0.1-1.0 ml) for 30 min (Experiment 1) or 1h (Experiment 2) prior to open-field test and in the open field or injected with CDP (10 mg/kg i.p.). CDP had predicted effects on behaviour, and the higher doses of lavender oil had some effects on behaviour similar to those of CDP. In Experiment 3, various combinations of pre-exposure times and amounts of lavender oil were used. With sufficient exposure time and quantity of lavender the same effects were obtained as in Experiment 2. Experiment 4 demonstrated that these behavioural effects of lavender could be obtained following pre-exposure, even if no oil was present in the open-field test. In Experiments 2-4, lavender oil increased immobility. Together, these experiments suggest that lavender oil does have anxiolytic effects in the open field, but that a sedative effect can also occur at the highest doses.