| ObjectivesTo study the effects and mechanisms of lavender essential oil on rat arterial pressure through olfactory pathway.MethodsThirty-two SD rats were randomly divided into four groups: lavender (1%); lavender (1‰);distilled water and control. The arterial pressure was monitored by MedLab 6.0 biological signal collecting and processing system for 100 min. The levels of catecholamine (CA) were detected by Enzyme-linked immunosorbent assay (ELISA). The levels of neuropeptide Y (NPY) were detected by radioimmunohistochemistry (RIA). The amount of c-fos,γ-aminobutyric acid (GABA) and noradrenalin (NE) were measured by immunohistochemistry and were semi-quantitative analysed for grey value by Image-Pro-Plus 6.0 picture analysis software. The Pearson correlation between peripheral levels of CA, NPY and grey value of GABA, NE in brain tissue were analysed by spss17.Results1. The general condition of rats in groups:The body weight of rats in groups were basically identical. There was no statistically significance (P>0.05). Thirty-two rats were used in this experiment and died six, the death rate was 16%. The death was due to the improper operation.2. The mean arterial pressure (MAP) in groups:The basic MAP between groups had no statistically significance (P>0.05). For lavender (1%), the MAP were down immediately after inhalation lavender essential oil, had down apparently in 30min, had down mostly in 100min, compared to distilled and control group, there had statistically significance(P<0.05). While for lavender (1‰), the MAP were down after inhalation of lavender essential oil , had no statistically significance (P>0.05). In 100 min, for lavender (1%); lavender(1‰);distilled water and control group, the MAP were down (15.5±0.4), (4.7±0.2), (1.5±0.1), (0.65±0.1) mmHg respectively. Compared to distilled water and control group, the MAP of lavender (1%) was significantly reduced (P<0.05), lavender (1‰) was no significantly reduced (P>0.05). Compared to distilled water and control group, the MAP of lavender (1%) were significantly reduced in 30, 40, 50, 60, 70, 80, 90, 100 min respectively (P<0.05).3. The peripheral levels of CA and NPY :For lavender (1%); lavender (1‰); distilled water; control group, the peripheral levels of CA were (114.09±8.81), (142.99±9.88), (147.99±7.15), (152.02±8.86) ng/ml respectively. Compared to distilled and water group, the CA levels of lavender (1%) was significantly reduced (P<0.05), lavender (1‰) was no significantly reduced (P>0.05). For lavender (1%); lavender (1‰); distilled water; control group, the peripheral levels of NPY were (1.36±0.02), (1.40±0.03), (1.53±0.05), (1.54±0.04)μg/L respectively. Compared to distilled and water group, the NPY levels of lavender (1%) was significantly reduced (P<0.05), lavender (1‰) was no significantly reduced (P>0.05).4. The expression of c-fos in brain tissue:The c-fos positive cells were dyed in brown. For lavender (1%); lavender (1‰), c-fos positive cells were distributed in brain cortex, hypothalamus , amygdala and so on consulting to The Rat Brain in Stereotaxic Coordinates. For distilled water and control group, c-fos positive cells were dispersed in brain tissue.5. GABA and NE positive cells were mainly distributed in brain tissue for lavender (1‰); distilled water and control group. For lavender (1%), the expression of GABA was up and NE was down.in paraventricular nucleus(PVN). For lavender (1%); lavender (1‰); distilled water; control group, grey value of GABA were (112.5±2.9), (139.5±3.9), (160.6±3.0), (169.2±3.8).Compared to distilled and water group, the GABA of lavender (1%) was significantly reduced (P<0.05), lavender (1‰) was no significantly reduced (P>0.05).For lavender (1%); lavender (1‰); distilled water; control group, grey value of NE were (154.6±2.6), (124.2±8.1), (117.6±8.0), (117.1±4.8). Compared to distilled and water group, the NE of lavender (1%) was significantly up (P<0.05), lavender (1‰) was no significantly up (P>0.05).6. The correlation analysis between peripheral levels of CA, NPY and grey value of GABA, NE in PVN:The correlation coefficient between levels of CA and grey value of GABA was 0.8 (P<0.05). The correlation coefficient between levels of CA and grey value of NE was -0.8(P<0.05). The correlation coefficient between levels of NPY and grey value of GABA was 0.9(P<0.05). The correlation coefficient between levels of NPY and grey value of NE was -0.7(P<0.05).Conclusions1. It's safe to inhale 1% and 1‰lavender 1essential oils in short time.2. The MAP were down immediately after inhalation (1%) lavender essential oil, had down apparently in 30min, had down mostly in 100min. The MAP were not down 3. Inhalation 1% lavender essential oil could inhibit the activity of sympathetic nerves and reduce the release of CA and NPY.4. The bioactivity of lavender essential oil may had close relationship with limbic system.5. The expression of GABA and NE of PVN could mediate the effect of reducing blood pressure through inhalation 1% lavender essential oil.6. The mechanisms on reducing blood pressure of inhaling 1% lavender essential oil could summarize as PVN modulate the activity of peripheral sympathetic nerves.
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