Several experimental studies have proved that activation of neuroinflammation pathways may contribute to the development of depression, a neuropsychiatric disorder disease. Our previous studies have shown the antidepressant properties of apelin, but the mechanism was unkown. This study was performed to verify whether the antidepressant effect of apelin was related to its anti-inflammation effect in the central nervous system. To achieve our aim, we selected the co-treatment of chronic stress and LPS to induced an inflammatory process in rats. The effect of this co-treatment was evaluated through the expression of inflammatory markers and glial cell activation. LPS injection co-treated with unpredictable chronic mild stress resulted in the activation of microglial cell and astrocyte, expression of inflammatory markers and depressive behaviors. Treatment with apelin significantly attenuates the deleterious effects in these rats. Our results showed that apelin improved depressive phenotype and decreased the activation of glial cells in stress co-treatment group. The down-regulations of p-NF-κB and p-IKKβ suggested that the effects are possibly mediated by inhibition of the NF-κB-mediated inflammatory response. These findings speculated that intracerebroventricular injection of apelin could be a therapeutic approach for the treatment of depression, and the antidepressant function of apelin may closely associated with its alleviation in neuroinflammation.

中文翻译：

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Apelin减轻慢性应激和脂多糖联合治疗大鼠的抑郁样行为和神经炎症

多项实验研究证明，神经炎症通路的激活可能会导致抑郁症（一种神经精神疾病）的发展。我们之前的研究已经显示了 apelin 的抗抑郁特性，但其机制尚不清楚。本研究旨在验证apelin的抗抑郁作用是否与其在中枢神经系统中的抗炎作用有关。为了实现我们的目标，我们选择了慢性应激和 LPS 的联合治疗来诱导大鼠的炎症过程。这种联合治疗的效果是通过炎症标志物的表达和神经胶质细胞的激活来评估的。LPS 注射与不可预测的慢性轻度应激共同治疗导致小胶质细胞和星形胶质细胞的激活、炎症标志物的表达和抑郁行为。用 apelin 治疗可显着减轻这些大鼠的有害影响。我们的结果表明，apelin 改善了应激联合治疗组的抑郁表型并降低了神经胶质细胞的活化。p-NF-κB 和 p-IKKβ 的下调表明这些作用可能是通过抑制 NF-κB 介导的炎症反应来介导的。这些发现推测，脑室内注射apelin可能是治疗抑郁症的一种治疗方法，apelin的抗抑郁作用可能与其减轻神经炎症密切相关。p-NF-κB 和 p-IKKβ 的下调表明这些作用可能是通过抑制 NF-κB 介导的炎症反应来介导的。这些发现推测，脑室内注射apelin可能是治疗抑郁症的一种治疗方法，apelin的抗抑郁作用可能与其减轻神经炎症密切相关。p-NF-κB 和 p-IKKβ 的下调表明这些作用可能是通过抑制 NF-κB 介导的炎症反应来介导的。这些发现推测，脑室内注射apelin可能是治疗抑郁症的一种治疗方法，apelin的抗抑郁作用可能与其减轻神经炎症密切相关。