Further understanding the mechanism for microglia activation is necessary for developing novel anti-inflammatory strategies. Our previous study found that the activation of sigma-1 receptor can effectively inhibit the neuroinflammation, independent of the canonical mechanisms, such as NF-κB, JNK and ERK inflammatory pathways. Thus, it is reasonable that an un-identified, non-canonical pathway contributes to the activation of microglia. In the present study, we found that a sigma-1 receptor agonist of 2-morpholin-4-ylethyl 1-phenylcyclohexane-1-carboxylate (PRE-084) suppressed lipopolysaccharide (LPS) elevated nitric oxide (NO) content in BV-2 microglia culture supernatant and LPS-raised mRNA levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS) in BV-2 microglia. Moreover, PRE-084 alleviated LPS-increased Ser 9 de-phosphorylation of glycogen synthase kinase-3 beta (GSK-3β), LPS-elevated catalytic activity of calcineurin, and LPS-raised percent and frequency of Ca²⁺ oscillatory BV-2 cells. We further found that the inhibitory effect of PRE-084 was reversed by a calcineurin activator of chlorogenic acid and a GSK-3β activator of pyrvinium. Moreover, an IP₃ receptor inhibitor of 2-aminoethoxydiphenyl borate mimicked the anti-inflammatory activity of PRE-084. Thus, we identified a noncanonical pro-neuroinflammary pathway of Ca²⁺ oscillation/Calcineurin/GSK-3β and the inhibition of this pathway is necessary for the anti-inflammatory activity of sigma-1 receptor activation.

进一步了解小胶质细胞激活的机制对于开发新的抗炎策略是必要的。我们之前的研究发现，sigma-1受体的激活可以有效抑制神经炎症，且不依赖于NF-κB、JNK和ERK炎症通路等经典机制。因此，未识别的非规范途径有助于小胶质细胞的激活是合理的。在本研究中，我们发现 2-吗啉-4-基乙基 1-苯基环己烷-1-甲酸 (PRE-084) 的 sigma-1 受体激动剂可抑制 BV-2 中脂多糖 (LPS) 升高的一氧化氮 (NO) 含量小胶质细胞培养上清液和 BV-2 小胶质细胞中 LPS 升高的肿瘤坏死因子-α (TNF-α)、白介素-1β (IL-1β)、诱导型一氧化氮合酶 (iNOS) 的 mRNA 水平。此外，PRE-084 减轻了 LPS 增加的糖原合成酶激酶 3 beta (GSK-3β) Ser 9 去磷酸化、LPS 升高的钙调神经磷酸酶催化活性，以及​​ LPS 升高的 Ca ²⁺振荡 BV-2 的百分比和频率细胞。我们进一步发现，绿原酸钙调神经磷酸酶激活剂和吡维铵 GSK-3β 激活剂可逆转 PRE-084 的抑制作用。此外，2-氨基乙氧基二苯基硼酸盐的 IP ₃受体抑制剂模仿了 PRE-084 的抗炎活性。因此，我们确定了 Ca ²⁺振荡/钙调神经磷酸酶/GSK-3β 的非经典促神经炎症途径，并且抑制该途径对于 sigma-1 受体激活的抗炎活性是必要的。