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Abstract
Virginian cedarwood ( Juniperus virginiana L.) essential oil is an important component of a very large number of fragrances, used in cosmetics or household products. Clary sage ( Salvia sclarea L.) essential oil is well known in aromatherapy for its sedative property. The essential oils of Virginian cedarwood’s crushed barks and clary sage’s leaves were analyzed by GC/MS. Respectively, seven and seventeen compounds; representing 78% and 94.13% of the essential oils, were identified. The main components of the cedar oil are cedrene alpha (25%) and cedrol (20%). The main components of the clary sage oil are linalyl acetate (69.4%) and linalool (11.9%). Cedarwood oil exhibits significant relaxing activity, influencing physiological and biochemical parameters in human. This shows repercussions on situational stress. Virginian Cedarwood essential oil activity is compared with clary sage essential oil, which proved to be less efficient on stress relief.
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As the outermost barrier of the body, the skin is exposed to multiple environmental factors, including temperature, humidity, mechanical stress, and chemical stimuli, such as odorants that are often used in cosmetic articles. Keratinocytes, the major cell type of the epidermal layer, express a variety of different sensory receptors that enable them to react to various environmental stimuli and process information in the skin. Here, we report the identification of a novel type of chemoreceptors in human keratinocytes, the olfactory receptors (ORs). We cloned and functionally expressed the cutaneous olfactory receptor, OR2AT4, and identified Sandalore, a synthetic sandalwood odorant, as an agonist of this receptor. Sandalore induces strong Ca(2+) signals in cultured human keratinocytes, which are mediated by OR2AT4, as demonstrated by receptor knockdown experiments using RNA interference. The activation of OR2AT4 induces a cAMP-dependent pathway and phosphorylation of extracellular signal-regulated kinases (Erk1/2) and p38 mitogen-activated protein kinases (p38 MAPK). Moreover, the long-term stimulation of keratinocytes with Sandalore positively affected cell proliferation and migration, and regeneration of keratinocyte monolayers in an in vitro wound scratch assay. These findings combined with our studies on human skin organ cultures strongly indicate that the olfactory receptor 2AT4 is involved in human keratinocyte reepithelialization during wound healing processes.Journal of Investigative Dermatology accepted article preview online, 07 July 2014; doi:10.1038/jid.2014.273.
A growing number of animal data strongly suggest that a hyporeactive hypothalamus-pituitary adrenal (HPA) axis may be pathologically significant by increasing the susceptibility to chronic inflammation. Following this line of evidence, the specific goal of the present study was to investigate the HPA axis in patients with atopic dermatitis (AD), a chronic allergic inflammatory disease. In addition, the sympathetic adrenomedullary (SAM) system as a second potent immunoregulatory and anti-inflammatory stress-response system has been examined.
AD patients (n = 36) and nonatopic control subjects (n = 37) were exposed to a standardized laboratory stressor consisting of a free speech and mental arithmetic task in front of an audience. Cortisol, ACTH, and catecholamine concentrations were assessed before and after the stressor. To investigate feedback sensitivity of the HPA axis, a low dose (0.5 mg) dexamethasone suppression test was also performed. AD patients showed significantly attenuated cortisol and ACTH responses to the stressor, whereas catecholamine levels were significantly elevated in atopic patients. No difference between the experimental groups was found in basal cortisol and ACTH concentrations, whereas basal catecholamine levels were significantly elevated. Analysis of cortisol levels after dexamethasone treatment suggested an intact feedback sensitivity in AD sufferers at the pituitary level. The present findings suggest that patients with AD demonstrate a blunted HPA axis responsiveness with a concurrent overreactivity of the SAM system to psychosocial stress. Considering the important immunoregulatory role of the HPA axis and the SAM system, especially under stressful conditions, an aberrant responsiveness of these neuroendocrine systems may increase the susceptibility to (allergic) inflammation and may be one psychobiological mechanism of stress-related aggravation of the disease.
Psychological conditions, including stress, compromise immune defenses. Although this concept is not novel, the molecular mechanism behind it remains unclear. Neuropeptide Y (NPY) in the central nervous system is a major regulator of numerous physiological functions, including stress. Postganglionic sympathetic nerves innervating lymphoid organs release NPY, which together with other peptides activate five Y receptors (Y1, Y2, Y4, Y5, and y(6)). Using Y1-deficient (Y1(-/-)) mice, we showed that Y1(-/-) T cells are hyperresponsive to activation and trigger severe colitis after transfer into lymphopenic mice. Thus, signaling through Y1 receptor on T cells inhibits T cell activation and controls the magnitude of T cell responses. Paradoxically, Y1(-/-) mice were resistant to T helper type 1 (Th1) cell-mediated inflammatory responses and showed reduced levels of the Th1 cell-promoting cytokine interleukin 12 and reduced interferon gamma production. This defect was due to functionally impaired antigen-presenting cells (APCs), and consequently, Y1(-/-) mice had reduced numbers of effector T cells. These results demonstrate a fundamental bimodal role for the Y1 receptor in the immune system, serving as a strong negative regulator on T cells as well as a key activator of APC function. Our findings uncover a sophisticated molecular mechanism regulating immune cell functions that can lead to stress-induced immunosuppression.
Perception of odours can provoke explicit reactions such as judgements of intensity or pleasantness, and implicit output such as skin conductance or heart rate variations. The main purpose of the present experiment was to ascertain: (i) the correlation between odour ratings (intensity, arousal, pleasantness and familiarity) and activation of the autonomic nervous system, and (ii) the inter-correlation between self-report ratings on intensity, arousal, pleasantness and familiarity dimensions in odour perception. Twelve healthy volunteers were tested in two separate sessions. Firstly, subjects were instructed to smell six odorants (isovaleric acid, thiophenol, pyridine, L-menthol, isoamyl acetate, and 1–8 cineole), while skin conductance and heart rate variations were being measured. During this phase, participants were not asked to give any judgement about the odorants. Secondly, subjects were instructed to rate the odorants on dimensions of intensity, pleasantness, arousal and familiarity (self-report ratings), by giving a mark between 1 (not at all intense, arousing, pleasant or familiar) and 9 (extremely intense, arousing, pleasant or familiar). Results indicated: (i) a pleasantness factor correlated with heart rate variations, (ii) an arousal factor correlated with skin conductance variations, and (iii) a strong correlation between the arousal and intensity dimensions. In conclusion, given that these correlations are also found in other studies using visual and auditory stimuli, these findings provide preliminary information suggesting that autonomic variations in response to olfactory stimuli are probably not modality specific, and may be organized along two main dimensions of pleasantness and arousal, at least for the parameters considered (i.e. heart rate and skin conductance).
Heart rate, frequency of skin conductance responses, and self-reported anxiety were measured during performance of a computer version of the Stroop Color-Word Interference Test, and during a non-conflicting control task involving the color naming of color patches. Stroop and control stimuli were presented individually in order to vary task pacing. Subjects (N = 48) were divided into three groups assigned to self-paced, externally-paced, and fast externally-paced conditions. Performance data revealed that the relative proportion of speed and accuracy reductions which resulted from the Stroop interference varied according to task pacing and pacing speed. Stroop performance was accompanied by heightened HR levels which were sustained throughout the series. State-Anxiety scores increased after both tasks, but only among subjects who completed a large number of trials, i.e. subjects in the self-paced and fast externally-paced groups. Skin conductance responses only varied according to task order and time within series, irrespective of Stroop interference or task pacing. Overall, the results remained in accordance with an effort account of the relationship between attention and cardiac activity. They also provided indications on how the Stroop test may act as an efficient laboratory stressor.
The use of a variety of electrophysiological techniques to determine the effects of odor on the nervous system is reviewed. Methods and problems associated with the collection of on-going EEG, chemosensory event-related potentials, and contingent negative variation data are discussed in depth as is the use of odors as modulators of brain potentials produced by other senses. In addition, the advantages of several seldom used EEG analysis techniques are discussed with respect to the unique problems of understanding olfaction.
Alertness, mood, and math computations were assessed in 11 healthy adults who sniffed a cosmetic cleansing gel with lavender floral blend aroma, developed to be relaxing using Mood Mapping. EEG patterns and heart rate were also recorded before, during, and after the aroma session. The lavender fragrance blend had a significant transient effect of improving mood, making people feel more relaxed, and performing the math computation faster. The self-report and physiological data are consistent with relaxation profiles during other sensory stimuli such as massage and music, as reported in the literature. The data suggest that a specific cosmetic fragrance can have a significant role in enhancing relaxation.
The salivary enzyme alpha-amylase has been proposed to indicate stress-reactive bodily changes. A previous study by the authors revealed marked increases in salivary alpha-amylase following psychosocial stress, indicating a stress-dependent activation of salivary alpha-amylase. Salivary alpha-amylase has been suggested to reflect catecholaminergic reactivity. Our aim was to assess/evaluate a possible relationship between salivary alpha-amylase and adrenergic parameters, i.e. catecholamines, as well as other stress markers. Using an intra-individual repeated measures design, 30 healthy young men underwent the Trier Social Stress Test (TSST), which consists of a mental arithmetic task and free speech in front of an audience and a control condition in randomized order. Salivary alpha-amylase and salivary cortisol as well as plasma catecholamines and cardiovascular activity were repeatedly measured before, during, and after both conditions. Significant differences were found between the stress and the rest condition in salivary alpha-amylase, salivary cortisol, plasma catecholamines, and cardiovascular parameters (heart rate, LF, HF, LF/HF). However, general alpha-amylase responses (area under the curve) were not associated with general responses in catecholamines and cortisol in the stress condition (r smaller than 0.25 for all analyses). Analysis of cardiovascular parameters indicates a positive relationship between amylase and sympathetic tone (LF/HF) during stress. Salivary alpha-amylase is sensitive to psychosocial stress. Since it does not seem to be closely related to other biological stress markers such as catecholamines and cortisol, salivary alpha-amylase may be a useful additional parameter for the measurement of stress.
Three studies explored whether odor can influence people's cognition and behavior without their being consciously aware of the influence. In two studies, we tested and confirmed that when participants were unobtrusively exposed to citrus-scented all-purpose cleaner, the mental accessibility of the behavior concept of cleaning was enhanced, as was indicated by faster identification of cleaning-related words in a lexical decision task and higher frequency of listing cleaning-related activities when describing expected behavior during the day. Finally, a third study established that the mere exposure to the scent of all-purpose cleaner caused participants to keep their direct environment more clean during an eating task. Awareness checks showed that participants were unaware of this influence. The present studies reveal the nonconscious influence that olfactory cues can have on thinking and doing.