CAJ | 학술논문

Ca2+稳态平衡的调节在少突胶质细胞功能和存活中起重要作用.大麻素CB1和CB2受体在许多细胞中调节Ca2+水平和/或K+电流.本文利用培养的少突胶质细胞中,通过增高细胞外K+浓度(50 mM诱导膜去极化,研究大麻素复合物在此过程引发钙内流中的作用.CB2受体激动剂ACEA导致去极化诱导的少突胶质细胞胞浆的Ca2+瞬变表达浓度依赖性抑制,最大效应为(94±3)%,半效应浓度(EC50)为(1.3±0.03)μM.这种作用可被CB2/CB2激动剂CP55、940、内源性大麻素类AEA和2-AG所模拟,但是CB2受体选择性激动剂JWH133没有作用.CB2受体拮抗剂AM251(1μM)也可减少细胞外高K+诱导的Ca2+反应.但不能防止ACEA(3 μM)诱发的抑制效应.然而,ACEA和AEA减少去极化诱导的Ca2+瞬变的能力在CB2受体敲除小鼠和经百日咳毒素预处理的少突胶质细胞中明显降低.内流性K2+通道阻断剂BaCI:(300 μM)和CsCl2(1 mM)降低电压诱导的Ca2+内流并部分阻断ACEA的抑制效应.本文表明,大麻素抑制少突胶质细胞中去极化诱导的Ca2+瞬变是通过包括PTX-敏感的Gi/o蛋白和阻断K2+内流通道的CB2受体依赖性和非依赖性机制.
Ca2+은태평형적조절재소돌효질세포공능화존활중기중요작용.대마소CB1화CB2수체재허다세포중조절Ca2+수평화/혹K+전류.본문이용배양적소돌효질세포중,통과증고세포외K+농도(50 mM유도막거겁화,연구대마소복합물재차과정인발개내류중적작용.CB2수체격동제ACEA도치거겁화유도적소돌효질세포포장적Ca2+순변표체농도의뢰성억제,최대효응위(94±3)%,반효응농도(EC50)위(1.3±0.03)μM.저충작용가피CB2/CB2격동제CP55、940、내원성대마소류AEA화2-AG소모의,단시CB2수체선택성격동제JWH133몰유작용.CB2수체길항제AM251(1μM)야가감소세포외고K+유도적Ca2+반응.단불능방지ACEA(3 μM)유발적억제효응.연이,ACEA화AEA감소거겁화유도적Ca2+순변적능력재CB2수체고제소서화경백일해독소예처리적소돌효질세포중명현강저.내류성K2+통도조단제BaCI:(300 μM)화CsCl2(1 mM)강저전압유도적Ca2+내류병부분조단ACEA적억제효응.본문표명,대마소억제소돌효질세포중거겁화유도적Ca2+순변시통과포괄PTX-민감적Gi/o단백화조단K2+내류통도적CB2수체의뢰성화비의뢰성궤제.
Regulation of Ca2+ homeostasis plays a critical role in oligodendrocyte function and survival. Canna-binoid CB2 and CB2 receptors have been shown to regulate Ca2+ levels and/or K+ currents in a variety of cell types. In this study we investigated the effect of cannabinoid compounds on the Ca2+ influx elicited in cultured oligodendro-cytes by transient membrane depolarization with an elevated extracellular K+ concentration (50 mM). The CB2 re-ceptor agonist arachidonoyl-chloro-ethanolamide (ACEA) elicited a concentration-dependent inhibition of depolariza-tion-evoked Ca2+ transients in oligodendroglial somata with a maximal effect (94 ± 3)% and an EC50 of 1.3 ±0.03 μM. This activity was mimicked by the CB2/CB2 agonist CP55,940, as well as by the endocannabinoids N-arachidonoyl-ethanolamine (anandamide, AEA) and 2-arachidonoylglycerol (2-AG), whereas the CB2 receptor se-lective agonist JWH133 was ineffective. The CB2 receptor antagonist AM251 (1 μM) also reduced the Ca2+ response evoked by high extracellular K+ and did not prevent the inhibition elicited by ACEA (3 μM). Nevertheless, the a-bility of ACEA and AEA to reduce depolarization-evoked Ca2+ transients was significantly reduced in oligodendro-cytes from CB2 receptor knockout mice, as well as by pretreatment with pertussis toxin. Bath application of the in-wardly rectifying K+ channels (Kir channels) blockers BaCl2 (300 μM) and CsCl2 (1 mM) reduced the size of volt-age-induced Ca2+ influx and partially prevented the inhibitory effect of ACEA. Our results indicate that eannabinoids inhibit depolarization-evoked Ca2+ transients in oligodendrocytes via CB2 receptor-independent and -dependent mech-anisms that involve the activation of PTX-sensitive Gi/o proteins and the blockade of Kir channels. C 2008 Wiley-Liss, Inc.