Dobrenis K, Makman M H, Stefano G B
Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Brain Res. 1995 Jul 24;686(2):239-48. doi: 10.1016/0006-8993(95)00452-v.
Evidence is presented for occurrence of opiate alkaloid-selective, opioid-peptide-insensitive receptor binding sites, labeled with [3H]morphine, in primary cultures of cat microglia and cat astrocytes, as well as on highly purified preparations of rat Kupffer cells. These receptors have been designated mu3 on the basis of their close similarity to receptors first found to be present on human peripheral blood monocytes. Exposure of the microglia to morphine and etorphine caused marked quantifiable changes in cellular morphology, including assumption of a more rounded shape and retraction of cytoplasmic processes; in contrast, several opioid peptides were without effect on morphology. The effects of morphine on microglial morphology were blocked by the opiate antagonist naloxone. These effects of drugs on morphology were as predicted for action via the mu3 receptor. Opiate alkaloid binding sites previously detected on the rat C6 glioma cell line were also characterized here as of the mu3 receptor subtype. It is proposed that mu3 receptors have broad distribution in different macrophage cell types of bone marrow lineage, including microglia and Kupffer cells. Furthermore, these receptors are not restricted to cells of bone marrow lineage, since they are also present on astrocytes.
有证据表明，在猫小胶质细胞和猫星形胶质细胞的原代培养物以及大鼠库普弗细胞的高度纯化制剂中，存在用[3H]吗啡标记的阿片生物碱选择性、对阿片肽不敏感的受体结合位点。基于它们与最初在人外周血单核细胞上发现的受体高度相似，这些受体被命名为μ3。小胶质细胞暴露于吗啡和埃托啡会导致细胞形态发生明显的可量化变化，包括变得更圆以及细胞质突起缩回；相比之下，几种阿片肽对形态没有影响。吗啡对小胶质细胞形态的影响被阿片拮抗剂纳洛酮阻断。药物对形态的这些影响正如通过μ3受体起作用所预测的那样。先前在大鼠C6胶质瘤细胞系上检测到的阿片生物碱结合位点在此也被鉴定为μ3受体亚型。有人提出，μ3受体在骨髓谱系的不同巨噬细胞类型中广泛分布，包括小胶质细胞和库普弗细胞。此外，这些受体并不局限于骨髓谱系的细胞，因为它们也存在于星形胶质细胞上。
