Black tea aroma inhibited increase of salivary chromogranin-A after arithmetic tasks

Alleviation of acute stress response by black pepper aroma administration

BACKGROUND

Black pepper is one of the most popular spices globally. As black pepper essential oil has not yet been used in the context of aromatherapy, this study examined the effect of black pepper aroma on cardiac and peripheral autonomic nervous system (ANS) activity under stressful conditions using an olfactometer to administer aroma in a precise and controlled manner to ensure reproducibility.

METHODS

A within-participant design experiment was conducted with 20 male university students who performed a 30-min calculation task as a short-term stressor under three aroma conditions: black pepper, ginger, and dipropylene glycol (DPG) (scentless air as a control). Each aroma was sporadically delivered (first 20 s of each 1-min interval) with the olfactometer during the task. Electrocardiograms and skin conductance level (SCL) were measured to evaluate ANS's physiological acute stress response. Subjective evaluations for the given stressful task and impressions on the types of aromas were assessed.

RESULTS

The physiological acute stress response induced by the short-term stressor, which is characterized by the enhancement of the heart rate (HR) and SCL and decreases in the heart rate variability (HRV), was suppressed with black pepper: the increase in HR and reduction in HRV from the baseline were 38.9% (p = 0.048 when compared with DPG) and 32.9% smaller (p = 0.002 for multiple comparisons) than those in DPG, respectively, and the increase of SCL was 15.5% smaller (p = 0.005 for multiple comparisons) than that in ginger. However, there was no significant difference in subjective scores among the conditions.

CONCLUSION

Although black pepper is a stimulative agent, the study findings showed that black pepper aroma alleviated the physiological acute stress response, which can be beneficial in aromatherapy under stressful conditions.

Orally Administered Plasmalogens Alleviate Negative Mood States and Enhance Mental Concentration: A Randomized, Double-Blind, Placebo-Controlled Trial

Background: Plasmalogens have been shown to improve neurodegenerative pathology and cognitive function. We hypothesized that plasmalogens work in small amounts as a kind of hormone interacting with a G protein-coupled receptor, and then explored the effects of scallop-derived purified plasmalogens on psychobehavioral conditions in a randomized placebo-controlled trial of college athletes in Japan.

Methods and materials: Eligible participants were male students aged 18–22 years who belonged to university athletic clubs. They were randomly allocated to either plasmalogen (2 mg per day) or placebo treatment of 4 weeks’ duration. The primary outcome was the T-score of the Profile of Mood States (POMS) 2–Adult Short, and the secondary outcomes included the seven individual scales of the POMS 2, other psychobehavioral measures, physical performance, and laboratory measurements. The trial was registered at the Japan Registry of Clinical Trials (jRCTs071190028).

Results: Forty participants (20 in the plasmalogen group and 20 in the placebo group) completed the 4-week treatment. The Total Mood Disturbance (TMD) score of the plasmalogen group showed a greater decrease at 4 weeks than that of the placebo group while the between-group difference was marginally significant (p = 0.07). The anger-hostility and fatigue-inertia scores of the POMS 2 decreased significantly in the plasmalogen group, but not in the placebo group, at 4 weeks. Between-group differences in those scores were highly significant (p = 0.003 for anger-hostility and p = 0.005 for fatigue-inertia). The plasmalogen group showed a slight decrease in the Athens Insomnia Scale at 2 weeks, and the between-group difference was near-significant (p = 0.07). The elapsed time in minute patterns on the Uchida-Kraepelin test, which is a marker of mental concentration, revealed significantly greater performance in the plasmalogen group than in the placebo group. There were no between-group differences in physical and laboratory measurements.

Conclusion: It is suggested that orally administered plasmalogens alleviate negative mood states and sleep problems, and also enhance mental concentration.

Smell and Stress Response in the Brain: Review of the Connection between Chemistry and Neuropharmacology

The stress response in the brain is not fully understood, although stress is one of the risk factors for developing mental disorders. On the other hand, the stimulation of the olfactory system can influence stress levels, and a certain smell has been empirically known to have a stress-suppressing effect, indeed. In this review, we first outline what stress is and previous studies on stress-responsive biomarkers (stress markers) in the brain. Subsequently, we confirm the olfactory system and review previous studies on the relationship between smell and stress response by species, such as humans, rats, and mice. Numerous studies demonstrated the stress-suppressing effects of aroma. There are also investigations showing the effects of odor that induce stress in experimental animals. In addition, we introduce recent studies on the effects of aroma of coffee beans and essential oils, such as lavender, cypress, α-pinene, and thyme linalool on the behavior and the expression of stress marker candidates in the brain. The transfer of volatile components into the brain is also discussed while using the results of thyme linalool as an example. These studies may provide a good opportunity to connect chemical research at the molecular level with neuropharmacological approaches in the future.

Subjective Effects of Inhaling Kuromoji Tea Aroma

Teas and various herbal teas are well-known beverages and are commonly consumed around the world. In this study, we focused on kuromoji tea. Kuromoji is a deciduous shrub of the Lauraceae family, and the plucked leaves and branches have been drunk as a tea in production areas for a long time. However, no studies have investigated the subjective and physiological effects of kuromoji tea. In this study, the effects of kuromoji tea were examined on the basis of the measurements of heart rate variability and cerebral blood flow, core body temperature and subjective assessments. Moreover, the results of this study showed that a pleasant subjective feeling could be obtained by sniffing the aroma of kuromoji teas, especially tea leaves. It was also found that the aroma of kuromoji teas has the potential to stimulate saliva secretion and increase subjective and physiological excitements in the oral cavity. 1,8-Cineole, linalool, terpinen-4-ol, carvone and geraniol were determined in both kuromoji leaves and branches. In this study, the beneficial effects of kuromoji teas when drunk conventionally were investigated.

Distribution of inhaled volatile β-caryophyllene and dynamic changes of liver metabolites in mice

β-caryophyllene (BCP), an essential oil component of many herbs and spices, has various biological activities as a functional food factor. A distinct feature of BCP is its volatile double-ring sesquiterpene structure. Orally administered BCP is reportedly detected in its intact form in mice serum; however, the distribution of inhaled volatile BCP throughout the body remains unknown. This study aimed to estimate the distribution properties of inhaled volatile BCP and to investigate its effects on metabolism. After mice were exposed to volatile BCP, it was detected in the lung, olfactory bulb, brain, serum, heart, liver, kidney, epididymal fat, and brown adipose tissue. BCP was further detected in the brain, liver, and brown adipose tissue 24 h after exposure. Metabolites related to glutathione metabolism were significantly altered in the liver. These results suggest that inhaled volatile BCP is widely distributed in murine tissues and affects the dynamics of metabolites in the liver.

Mechanisms Underlying the Anti-Depressive Effects of Regular Tea Consumption

This article is a comprehensive review of the literature pertaining to the antidepressant effects and mechanisms of regular tea consumption. Meta-data supplemented with recent observational studies were first analyzed to assess the association between tea consumption and depression risk. The literature reported risk ratios (RR) were 0.69 with 95% confidence intervals of 0.62-0.77. Next, we thoroughly reviewed human trials, mouse models, and in vitro experiments to determine the predominant mechanisms underlying the observed linear relationship between tea consumption and reduced risk of depression. Current theories on the neurobiology of depression were utilized to map tea-mediated mechanisms of antidepressant activity onto an integrated framework of depression pathology. The major nodes within the network framework of depression included hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, inflammation, weakened monoaminergic systems, reduced neurogenesis/neuroplasticity, and poor microbiome diversity affecting the gut-brain axis. We detailed how each node has subsystems within them, including signaling pathways, specific target proteins, or transporters that interface with compounds in tea, mediating their antidepressant effects. A major pathway was found to be the ERK/CREB/BDNF signaling pathway, up-regulated by a number of compounds in tea including teasaponin, L-theanine, EGCG and combinations of tea catechins and their metabolites. Black tea theaflavins and EGCG are potent anti-inflammatory agents via down-regulation of NF-κB signaling. Multiple compounds in tea are effective modulators of dopaminergic activity and the gut-brain axis. Taken together, our findings show that constituents found in all major tea types, predominantly L-theanine, polyphenols and polyphenol metabolites, are capable of functioning through multiple pathways simultaneously to collectively reduce the risk of depression.