沉香为瑞香科沉香属Aquilaria Lam.和拟沉香属Gyrinops Gaertn.植物含有树脂的木材。《本草原始》等古籍记载，沉香具有“益气和神”的功效，古代宫廷及民间常加热熏蒸沉香用于安神、缓解压力、改善睡眠，尤以沉香精油效果更加。已有研究表明沉香精油腹腔注射给药可缓解小鼠的抑郁症状、降低小鼠HPA轴的高敏感性并提高海马组织中5-HT等神经递质水平。沉香提取物及其分离化合物具有良好的抗神经炎症活性及神经保护作用，故推测沉香精油抗抑郁作用可能还与其抗炎和神经保护作用通路相关，但目前尚未见到相关研究，且其药效物质仍不明确，极大阻碍了沉香的药用及健康产品开发。此外，水蒸气蒸馏法和超临界CO₂流体萃取法是目前市售沉香精油常用的2种提取方法，但不同方法提取的精油香味及市场使用反馈效果差异较大，可能因其化学成分及其生物活性也存在差异。

    因此，本文拟研究沉香精油化合物组成及抗抑郁活性，采用HS-SPME-GC-MS和分子对接技术探寻沉香精油香薰抗抑郁的药效成分，并探讨沉香精油香薰给药对LPS诱导炎症性抑郁小鼠行为学影响及其作用机制。具体实验及结果如下：

（1）研究比较通体香、板头香和奇楠香3种代表性沉香分别采用水蒸气蒸馏法和超临界CO₂流体萃取法得到的沉香精油的化学成分和抗抑郁作用，结果表明，2种提取方法所得的精油成分具有较大差异，2种精油主要成分均为倍半萜类化合物，但超临界CO₂流体萃取法不仅精油提取率高，所得精油化合物数目多，且含有水蒸气蒸馏法无法提取得到的4个较高含量的2-（2苯乙基）色酮类化合物；但在同等浓度或剂量下，水蒸气蒸馏沉香精油香薰对缓解LPS诱导的小鼠抑郁样行为的能力优于超临界CO₂流体萃取沉香精油。

（2）建立并优化了基于HS-SPME-GC-MS的小鼠血清及脑组织样本中沉香挥发性成分分析方法，发现水蒸气蒸馏沉香精油中的Aromadendrene oxide 2、γ-Maaliene、Aristoler和Spathulenol等25种化合物（其中24种为倍半萜类化合物）可通过香薰和腹腔注射给药方式进入小鼠血清及脑组织中；对25种入血成分和抗抑郁药物靶点（HTR1A、HTR2A、D2、MAOA、AKT）进行分子对接，结合结果表明，所有成分与靶标蛋白的结合能均低于-7 kcal·mol^-1，提示HTR1A、HTR2A等靶蛋白可能是沉香精油抗抑郁的关键靶标。

（3）为探讨沉香精油香薰给药抗抑郁的作用机制，对小鼠炎症通路及脑源性神经营养因子（BDNF）通路相关蛋白表达进行检测，结果发现，水蒸气蒸馏沉香精油香薰吸入给药组可降低LPS小鼠血清及皮质组织中炎症因子TNF-α、IL-6和IL-1β的含量，且高剂量的沉香精油香薰吸入给药具有与阳性药帕罗西汀相似的抑制小鼠海马组织NF-κB/IκB-α通路相关蛋白、提高小鼠海马组织BDNF及其受体蛋白TrkB和调控蛋白CREB的表达水平的作用，揭示沉香精油香薰可能是通过调控小鼠神经炎症通路和BDNF通路相关蛋白的表达从而发挥抗抑郁作用。

    本研究对不同提取方式所得沉香精油的化合物组成及抗抑郁活性进行对比，并分析沉香精油香薰给药对LPS诱导的炎症性抑郁小鼠行为学影响及其作用机制与药效成分，可为沉香精油的质量评价以及抗抑郁新药和沉香镇静安神养生香产品的开发提供科学依据。

    Agarwood is the resinous wood of Aquilaria Lam. and Gyrinops Gaertn. plants of the Thymelaeaceae family. The Ben Cao Yuan Shi and other ancient books reported that agarwood has "benefit qi and Shen" effect; the ancient court and folk often heated agarwood to calm the mind, relieve stress and improve sleep, with the agarwood essential oil (AEO) having the best effect. Studies have also shown that (AEO), when injected intraperitoneally into mice, can reduce the hypersensitivity of the HPA axis and increase neurotransmitters such as 5-HT. The extract of agarwood and the sesquiterpenes and chromones it contains also exhibit good anti-neurological and neuroprotective effects. It can be seen that the AEO's volatile components can also have a sedative and calming effect, but its medicinal substances are still unclear. In addition, hydro-distillation (HD) and the supercritical CO₂ fluid extraction (SFE) method are currently commercially available for agarwood commonly used, the fragrance and the market feedback of AEOs extracted by the two methods may cause different chemical compositions that lead to differences in pharmacological activity.

    Therefore, in this paper, we intend to investigate the composition and antidepressant activities of different AEOs, explore the behavioral effects of aromatherapy administration of AEO on LPS-induced depression in mice and its mechanism of action, and explore the pharmacodynamic components of the antidepressant aromatherapy of it using HS-SPME-GC-MS and molecular docking techniques. The specific experiments and results are as follows:

(1)The study compared the chemical composition and antidepressant effects of agarwood essential oils obtained by HD and SFE from agarwood of Agar-Wit, agarwood of trunk-prunning, and Chi-Nan, respectively. The results showed that the compositions of the two essential oil extraction methods were significantly different, and the AEOs extracted by SFE contained higher levels of 2-(2-phenethyl)chromone. And when given to mice via inhalation, AEO extracted by HD also had a better effect on reducing LPS-induced inflammatory and depressive disease behavior.

(2)A method based on HS-SPME-GC-MS was developed and optimized for the analysis of volatile components of AEO in mouse serum and brain tissue, and 25 compounds (including 24 sesquiterpenes) including Aromadendrene oxide 2, γ-Maaliene, Aristoler and Spathulenol, were found to enter mouse serum and brain tissue. The molecular docking of these 25 components and antidepressant targets (HTR1A, HTR2A, D2, MAOA and AKT) showed that the binding energy of all the components to the target proteins was below -7 kcal·mol^-1, suggesting that HTR1A, HTR2A and other target proteins may be the key targets of antidepressants in AEO.

(3)To verify the antidepressant pharmacological activity and the effect on neuroinflammation and BDNF in the brain of LPS-induced depressed mice treated by AEO, it was found that AEO aromatherapy reduced the increase of LPS-induced inflammatory factors TNF-α, IL-6 and IL-1β in serum and brain tissues of mice, and the inhalation administration of medium and high doses of AEO had a similar effect to that of paroxetine. The inhalation of AEO had similar effects to paroxetine in blocking the activation of NF-κB/IκB-α pathway and increased the expression levels of BDNF and its receptor protein TrkB and regulatory protein CREB in hippocampal tissues of mice to different degrees, revealing that AEO may exert its anti-neuroinflammatory and neuroprotective effects by regulating the activation of the LPS-induced inflammatory pathway and the inhibition of the expression of brain-derived neurotrophic factor pathway in mice, thus exerting its antidepressant effects.

    In this study, we compared the compound composition and antidepressant activities of different types of AEOs, and investigated the behavioral effects of AEO aromatherapy administration on mice with an LPS-induced depression model and its mechanism of action and pharmacodynamic components. This study may provide a scientific basis for the quality evaluation of AEO and the development of new antidepressant drugs and sedative and tranquilizing aromatic incense products.