Kaminski N E, Abood M E, Kessler F K, Martin B R, Schatz A R
Department of Pharmacology and Toxicology, Medical College of Virginia/Virginia Commonwealth University, Richmond 23298.
Mol Pharmacol. 1992 Nov;42(5):736-42.
Extensive behavioral and biochemical characterization of cannabinoid-mediated effects on the central nervous system has revealed at least three lines of evidence supporting the role of a putative guanine nucleotide-binding protein-coupled cannabinoid receptor for cannabimimetic effects, (i) stereoselectivity, (ii) inhibition of the adenylate cyclase/cAMP second messenger system, and (iii) radioligand-binding studies with the synthetic cannabinoid [3H]CP-55,940 indicating a high degree of specific binding to brain tissue preparations. Based on recent findings from our laboratory demonstrating that delta 9-tetrahydrocannabinol markedly inhibited forskolin-stimulated cAMP accumulation in mouse spleen cells, the presence of a guanine nucleotide-binding protein-coupled cannabinoid receptor associated with mouse spleen cells and its functional role in immune modulation were investigated. In the present studies, stereoselective immune modulation was observed with the synthetic bicyclic cannabinoid (-)-CP-55,940 versus (+) CP-56,667 and with 11-OH-delta 8-tetrahydrocannabinol-dimethylheptyl, (-)-HU-210 versus (+)-HU-211. In both cases, the (-)-enantiomer demonstrated greater immunoinhibitory potency than the (+)-isomer, as measured by the in vitro sheep red blood cell antibody-forming cell response. Radioligand binding studies produced a saturation isotherm exhibiting approximately 45-65% specific binding to mouse spleen cells. Scatchard analysis demonstrated a single binding site on spleen cells, possessing a Kd of 910 pM and a Bmax of approximately 1000 receptors/spleen cell. RNA polymerase chain reaction of isolated splenic RNA using specific primers for the cannabinoid receptor resulted in the amplification of a 854-kilobase predicted product that hybridized with cannabinoid receptor cDNA, demonstrating the presence of cannabinoid receptor mRNA in mouse spleen. Together, these findings strongly support the role of a cannabinoid receptor in immune modulation by cannabimimetic agents.
对大麻素介导的中枢神经系统效应进行的广泛行为学和生物化学特征研究揭示了至少三条证据，支持一种假定的鸟嘌呤核苷酸结合蛋白偶联大麻素受体在类大麻效应中所起的作用，（i）立体选择性，（ii）对腺苷酸环化酶/cAMP第二信使系统的抑制作用，以及（iii）用合成大麻素[3H]CP-55,940进行的放射性配体结合研究表明其与脑组织制剂具有高度特异性结合。基于我们实验室最近的发现，即δ9-四氢大麻酚显著抑制福斯高林刺激的小鼠脾细胞中cAMP的积累，对与小鼠脾细胞相关的鸟嘌呤核苷酸结合蛋白偶联大麻素受体的存在及其在免疫调节中的功能作用进行了研究。在本研究中，观察到合成双环大麻素（-）-CP-55,940与（+）CP-56,667以及11-羟基-δ8-四氢大麻酚-二甲基庚基、（-）-HU-210与（+）-HU-211之间存在立体选择性免疫调节。在这两种情况下，通过体外绵羊红细胞抗体形成细胞反应测定，（-）-对映体显示出比（+）-异构体更强的免疫抑制效力。放射性配体结合研究产生了一个饱和等温线，显示与小鼠脾细胞的特异性结合约为45-65%。Scatchard分析表明脾细胞上有一个单一结合位点，Kd为910 pM，Bmax约为1000个受体/脾细胞。使用大麻素受体特异性引物对分离的脾RNA进行RNA聚合酶链反应，得到了一个854碱基的预测产物，该产物与大麻素受体cDNA杂交，证明小鼠脾中存在大麻素受体mRNA。总之，这些发现有力地支持了大麻素受体在类大麻制剂免疫调节中的作用。
