Mechanism of changes induced in plasma glycerol by scent stimulation with grapefruit and lavender essential oils

Bioactive Compounds and Their Influence on Postnatal Neurogenesis

Since postnatal neurogenesis was revealed to have significant implications for cognition and neurological health, researchers have been increasingly exploring the impact of natural compounds on this process, aiming to uncover strategies for enhancing brain plasticity. This review provides an overview of postnatal neurogenesis, neurogenic zones, and disorders characterized by suppressed neurogenesis and neurogenesis-stimulating bioactive compounds. Examining recent studies, this review underscores the multifaceted effects of natural compounds on postnatal neurogenesis. In essence, understanding the interplay between postnatal neurogenesis and natural compounds could bring novel insights into brain health interventions. Exploiting the therapeutic abilities of these compounds may unlock innovative approaches to enhance cognitive function, mitigate neurodegenerative diseases, and promote overall brain well-being.

The effects of linalool acupoint application therapy on sleep regulation

The Shenque acupoint is located in the umbilicus of the human body. In the human body meridians, the Shenque acupoint can regulate body functions. The Shenque acupoint was one of the important acupuncture acupoints for the treatment of insomnia. However, the effect of linalool applied at the Shenque acupoint to improve sleep was unknown. This study explored the hypnotic and sedative effects of the main component of lavender, linalool, on the Shenque acupoint of mice and rats. The effects on the sleep latency and sleep duration were studied with the supra-threshold dose of pentobarbital sodium, and the effects on the sleep rate were studied with the sub-threshold dose of pentobarbital sodium. In order to further study the feasibility and superiority of linalool administered at the Shenque acupoint, a pharmacokinetic study was carried out. The pharmacodynamic results showed that the mice and rats treated with linalool at Shenque had the highest sleep rate, the shortest sleep latency, and the longest sleep duration compared with other groups. The T max and t 1/2 of the LS were longer than those of the LO, and had the characteristics of sustained release. The relative bioavailability of LS was 323.0 ± 31.66%. This showed that the combination of linalool and the Shenque acupoint had greater medicinal effects. This development will provide a new direction for improving sleep.

Increase in diastolic blood pressure induced by fragrance inhalation of grapefruit essential oil is positively correlated with muscle sympathetic nerve activity

Fragrance inhalation of essential oils is widely used in aromatherapy, and it is known to affect blood pressure (BP) and heart rate (HR) via autonomic control of circulation. In this study, we aimed to test the hypothesis that the changes in hemodynamics with fragrance inhalation were observed along with changes in muscle sympathetic nerve activity (MSNA). In study 1, thirteen healthy men were exposed to fragrance stimulation of grapefruit essential oil for 10 min, and BP, HR, and MSNA were continuously measured. In study 2, another nine healthy men were exposed to the same fragrance stimulation; responses in BP and HR were continuously measured, and plasma noradrenaline and cortisol concentrations were determined. We found that diastolic BP increased significantly during fragrance inhalation, while the other variables remained unchanged in both studies. Although MSNA burst frequency, burst incidence, and total activity remained unchanged during fragrance inhalation, we found a significant linear correlation between changes in diastolic BP in the last 5 min of fragrance inhalation and changes in MSNA burst frequency. The plasma cortisol concentration decreased significantly at 10 min of fragrance inhalation, though the noradrenaline concentration remained unchanged. These results suggest, for the first time, that changes in BP with fragrance inhalation of essential oil are associated with changes in MSNA even with decreased stress hormone.

Olfactory stimulation modulates the blood glucose level in rats

In both humans and animals, chemosensory stimuli, including odors and tastes, induce a variety of physiologic and mental responses related to energy homeostasis, such as glucose kinetics. The present study examined the importance of olfactory function in glucose kinetics following ingestion behavior in a simplified experimental scenario. We applied a conventional glucose tolerance test to rats with and without olfactory function and analyzed subsequent blood glucose (BG) curves in detail. The loss of olfactory input due to experimental damage to the olfactory mucosa induced a marked decrease in the area under the BG curve. Exposure to grapefruit odor and its main component, limonene, both of which activate the sympathetic nerves, before glucose loading also greatly depressed the BG curve. Pre-loading exposure to lavender odor, a parasympathetic activator, stabilized the BG level. These results suggest that olfactory function is important for proper glucose kinetics after glucose intake and that certain fragrances could be utilized as tools for controlling BG levels.

Olfactory stimulatory with grapefruit and lavender oils change autonomic nerve activity and physiological function

This review summarizes the effects of olfactory stimulation with grapefruit and lavender oils on autonomic nerve activity and physiological function. Olfactory stimulation with the scent of grapefruit oil (GFO) increases the activity of sympathetic nerves that innervate white and brown adipose tissues, the adrenal glands, and the kidneys, decreases the activity of the gastric vagal nerve in rats and mice. This results in an increase in lipolysis, thermogenesis, and blood pressure, and a decrease in food intake. Olfactory stimulation with the scent of lavender oil (LVO) elicits the opposite changes in nerve activity and physiological variables. Olfactory stimulation with scent of limonene, a component of GFO, and linalool, a component of LVO, has similar effects to stimulation with GFO and LVO, respectively. The histamine H1-receptor antagonist, diphenhydramine, abolishes all GFO-induced changes in nerve activity and physiological variables, and the hitstamine H3-receptor antagonist, thioperamide, eliminates all LVO-induced changes. Lesions to the hypothalamic suprachiasmatic nucleus and anosmic treatment with ZnSO4 also abolish all GFO- and LVO-induced changes. These findings indicate that limonene and linalool might be the active substances in GFO and LVO, and suggest that the suprachiasmatic nucleus and histamine are involved in mediating the GFO- and LVO-induced changes in nerve activity and physiological variables.

Lavender and the nervous system

Lavender is traditionally alleged to have a variety of therapeutic and curative properties, ranging from inducing relaxation to treating parasitic infections, burns, insect bites, and spasm. There is growing evidence suggesting that lavender oil may be an effective medicament in treatment of several neurological disorders. Several animal and human investigations suggest anxiolytic, mood stabilizer, sedative, analgesic, and anticonvulsive and neuroprotective properties for lavender. These studies raised the possibility of revival of lavender therapeutic efficacy in neurological disorders. In this paper, a survey on current experimental and clinical state of knowledge about the effect of lavender on the nervous system is given.

Diet-induced obesity resistance of Kv1.3-/- mice is olfactory bulb dependent

Gene-targeted deletion of the voltage-gated potassium channel, Kv1.3 (Kv1.3-/-), increases olfactory sensitivity and discriminatory ability, and causes resistance to diet-induced obesity (DIO) in mice. The present study aimed to determine whether the enhanced olfactory ability of the Kv1.3-/- mouse contributes to the resistance to DIO. Kv1.3+/+ and Kv1.3-/- mice were subject to bilateral olfactory bulbectomy (OBX) or sham surgery at 9 weeks of age and placed on either a control chow diet or a 32% moderately high-fat diet (MHF). Caloric and water intake, locomotor activity and oxygen consumption were monitored after 5 weeks of diet treatment. At the end of 26 weeks of diet treatment, fat pad weight and blood chemistry were evaluated. Kv1.3+/+ mice exhibited a significant increase in weight, adiposity, fasting glucose and fasting leptin in response to the MHF-diet, with or without OBX. When treated with a MHF-diet, Kv1.3-/- mice gained significantly less weight than Kv1.3+/+ mice and exhibited a significant increase in light phase metabolism. OBX of Kv1.3-/- mice prevented the resistance to DIO and concomitant up-regulation of light phase metabolism at the same time as decreasing dark phase metabolism and total energy expenditure. These findings suggest that pathways activated in Kv1.3-/- that increased energy expenditure and led to resistance to DIO are olfactory bulb dependent. Thus, these findings add to a growing body of evidence suggesting that the olfactory system can modulate the pathways involved in the regulation of energy balance.

Activities of ten essential oils towards Propionibacterium acnes and PC-3, A-549 and MCF-7 cancer cells

Ten essential oils, namely, mint (Mentha spicata L., Lamiaceae), ginger (Zingiber officinale Rosc., Zingiberaceae), lemon (Citrus limon Burm.f., Rutaceae), grapefruit (Citrus paradisi Macf., Rutaceae), jasmine (Jasminum grandiflora L., Oleaceae), lavender (Mill., Lamiaceae), chamomile (Matricaria chamomilla L., Compositae), thyme (Thymus vulgaris L., Lamiaceae), rose (Rosa damascena Mill., Rosaceae) and cinnamon (Cinnamomum zeylanicum N. Lauraceae) were tested for their antibacterial activities towards Propionibacterium acnes and in vitro toxicology against three human cancer cell lines. Thyme, cinnamon and rose essential oils exhibited the best antibacterial activities towards P. acnes, with inhibition diameters of 40 ± 1.2 mm, 33.5 ± 1.5 mm and 16.5 ± 0.7 mm, and minimal inhibitory concentrations of 0.016% (v/v), 0.016% (v/v) and 0.031% (v/v), respectively. Time-kill dynamic procedures showed that thyme, cinnamon, rose, and lavender essential oils exhibited the strongest bactericidal activities at a concentration of 0.25% (v/v), and P. acnes was completely killed after 5 min. The thyme essential oil exhibited the strongest cytotoxicity towards three human cancer cells. Its inhibition concentration 50% (IC₅₀) values on PC-3, A549 and MCF-7 tumor cell lines were 0.010% (v/v), 0.011% (v/v) and 0.030% (v/v), respectively. The cytotoxicity of 10 essential oils on human prostate carcinoma cell (PC-3) was significantly stronger than on human lung carcinoma (A549) and human breast cancer (MCF-7) cell lines.

Body fat mass reduction and up-regulation of uncoupling protein by novel lipolysis-promoting plant extract

We have found natural products exhibiting lipolysis-promoting activity in subcutaneous adipocytes, which are less sensitive to hormones than visceral adipocytes. The activities and a action mechanisms of a novel plant extract of Cirsium oligophyllum (CE) were investigated in isolated adipocytes from rat subcutaneous fat, and its fat-reducing effects by peroral administration and topical application were evaluated in vivo. CE-induced lipolysis was synergistically enhanced by caffeine, a phosphodiesterase inhibitor, and was reduced by propranolol, a β adrenergic antagonist. The peroral administration of 10% CE solution to Wistar rats for 32 days reduced body weight gain, subcutaneous, and visceral fat weights by 6.6, 26.2, and 3.0%, respectively, as compared to the control group. By the topical application of 2% of this extract to rats for 7 days, weight of subcutaneous fat in the treated skin was reduced by 23.2%. This fat mass reduction was accompanied by the up-regulation of uncoupling protein 1 (UCP), a principal thermogenic mitochondrial molecule related to energy dissipating, in subcutaneous fat and UCP3 in skin except for the fat layer. These results indicate that CE promotes lipolysis via a mechanism involving the β adrenergic receptor, and affects the body fat mass. This fat reduction may be partially due to UCP up-regulation in the skin including subcutaneous fat. This is the first report showing that repeated lipolysis promotion through CE administration may be beneficial for the systematic suppression of body fat accumulation or the control of fat distribution in obesity.

Day-night difference in thermoregulatory responses to olfactory stimulation

Previously, we observed that olfactory stimulation with scent of grapefruit oil (SGFO) or scent of lavender oil (SLVO) affected, elevated or lowered brown adipose tissue temperature (BAT-T) in conscious mice, respectively. In the present study, to test the day-night difference in the actions of olfactory stimulations, we examined the responses of BAT-T and body temperature (BT) measured as the abdominal temperature to SGFO or SLVO during day-time at 14:00 and night-time at 2:00 in conscious rats. In the light period, BAT-T and BT were suppressed after SLVO and elevated after SGFO whereas in the dark period, these parameters remained unchanged with olfactory stimulations. Bilateral lesions of the hypothalamic suprachiasmatic nucleus (SCN) eliminated the effects of olfactory stimulations with SGFO and SVLO on BAT-T and BT. Moreover, sympathetic nerve activity innervating brown adipose tissue (BAT-SNA) changes after SGFO or SLVO were abolished in SCN-lesioned rats. Thus, we concluded that there is day-night difference in the effects of SGFO or SLVO on BAT-T and BT, and that the SCN might be involved in these effects.