Dang Duy-Khanh, Shin Eun-Joo, Mai Anh-Thu, Jang Choon-Gon, Nah Seung-Yeol, Jeong Ji Hoon, Ledent Catherine, Yamamoto Tsuneyuki, Nabeshima Toshitaka, Onaivi Emmanuel S, Kim Hyoung-Chun
Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea.
Department of Pharmacology, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Free Radic Biol Med. 2017 Jul;108:204-224. doi: 10.1016/j.freeradbiomed.2017.03.033. Epub 2017 Mar 29.
Accumulating evidence suggests that cannabinoid ligands play delicate roles in cell survival and apoptosis decisions, and that cannabinoid CB1 receptors (CB1R) modulate dopaminergic function. However, the role of CB1R in methamphetamine (MA)-induced dopaminergic neurotoxicity in vivo remains elusive. Multiple high doses of MA increased phospho-ERK and CB1R mRNA expressions in the striatum of CB1R (+/+) mice. These increases were attenuated by CB1R antagonists (i.e., AM251 and rimonabant), an ERK inhibitor (U0126), or dopamine D2R antagonist (sulpiride). In addition, treatment with MA resulted in dopaminergic impairments, which were attenuated by CB1R knockout or CB1R antagonists (i.e., AM251 and rimonabant). Consistently, MA-induced oxidative stresses (i.e., protein oxidation, lipid peroxidation and reactive oxygen species) and pro-apoptotic changes (i.e., increases in Bax, cleaved PKCδ- and cleaved caspase 3-expression and decrease in Bcl-2 expression) were observed in the striatum of CB1R (+/+) mice. These toxic effects were attenuated by CB1R knockout or CB1R antagonists. Consistently, treatment with four high doses of CB1R agonists (i.e., WIN 55,212-2 36mg/kg and ACEA 16mg/kg) also resulted in significant oxidative stresses, pro-apoptotic changes, and dopaminergic impairments. Since CB1R co-immunoprecipitates PKCδ in the presence of MA or CB1R agonists, we applied PKCδ knockout mice to clarify the role of PKCδ in the neurotoxicity elicited by CB1Rs. CB1R agonist-induced toxic effects were significantly attenuated by CB1R knockout, CB1R antagonists or PKCδ knockout. Therefore, our results suggest that interaction between D2R, ERK and CB1R is critical for MA-induced dopaminergic neurotoxicity and that PKCδ mediates dopaminergic damage induced by high-doses of CB1R agonist.
越来越多的证据表明，大麻素配体在细胞存活和凋亡决定中发挥着微妙的作用，并且大麻素CB1受体（CB1R）调节多巴胺能功能。然而，CB1R在体内甲基苯丙胺（MA）诱导的多巴胺能神经毒性中的作用仍不清楚。多次高剂量的MA增加了CB1R（+/+）小鼠纹状体中磷酸化ERK和CB1R mRNA的表达。这些增加被CB1R拮抗剂（即AM251和利莫那班）、ERK抑制剂（U0126）或多巴胺D2R拮抗剂（舒必利）减弱。此外，MA治疗导致多巴胺能损伤，CB1R基因敲除或CB1R拮抗剂（即AM251和利莫那班）可减弱这种损伤。同样，在CB1R（+/+）小鼠的纹状体中观察到MA诱导的氧化应激（即蛋白质氧化、脂质过氧化和活性氧）和促凋亡变化（即Bax、裂解的PKCδ和裂解的caspase 3表达增加以及Bcl-2表达减少）。这些毒性作用被CB1R基因敲除或CB1R拮抗剂减弱。同样，用四种高剂量的CB1R激动剂（即WIN 55,212-2 36mg/kg和ACEA 16mg/kg）治疗也导致了显著的氧化应激、促凋亡变化和多巴胺能损伤。由于在存在MA或CB1R激动剂的情况下，CB1R与PKCδ共免疫沉淀，我们应用PKCδ基因敲除小鼠来阐明PKCδ在CB1R引发神经毒性中的作用。CB1R激动剂诱导的毒性作用被CB1R基因敲除、CB1R拮抗剂或PKCδ基因敲除显著减弱。因此，我们的结果表明，D2R、ERK和CB1R之间的相互作用对于MA诱导的多巴胺能神经毒性至关重要，并且PKCδ介导高剂量CB1R激动剂诱导的多巴胺能损伤。
