Vial D, Piomelli D
Unité de Neurobiologie et Pharmacologie de l'INSERM, Paris, France.
J Neurochem. 1995 Jun;64(6):2765-72. doi: 10.1046/j.1471-4159.1995.64062765.x.
Several G(i)-linked neurotransmitter receptors, including dopamine D2 receptors, act synergistically with Ca(2+)-mobilizing stimuli to potentiate release of arachidonic acid (AA) from membrane phospholipids. In brain, AA and its metabolites are thought to act as intracellular second messengers, suggesting that receptor-dependent potentiation of AA release may participate in neuronal transmembrane signaling. To study the molecular mechanisms underlying this modulatory response, we have now used Chinese hamster ovary cells transfected with rat D2-receptor cDNA, CHO(D2). Two antisense oligodeoxynucleotides corresponding to distinct cDNA sequences of cytosolic, AA-specific phospholipase A2 (cPLA2) were synthesized and added to cultures of CHO(D2) cells. Incubation with antisense oligodeoxynucleotides inhibited D2 receptor-dependent release of AA but had no effect on D2-receptor binding or D2 inhibition of cyclic AMP accumulation. In addition, pharmacological experiments showed that D2 receptor-dependent AA release was prevented by nonselective phospholipase inhibitors (such as mepacrine) but not by inhibitors of membrane-bound, non-AA-specific PLA2 (such as p-bromophenacyl bromide). cPLA2 is expressed in brain tissue. The results, showing that cPLA2 participates in receptor-dependent potentiation of AA release in CHO(D2) cells, suggest that this phospholipase may serve a similar signaling function in brain.
几种与G(i)偶联的神经递质受体，包括多巴胺D2受体，可与动员Ca(2+)的刺激协同作用，以增强膜磷脂中花生四烯酸（AA）的释放。在大脑中，AA及其代谢产物被认为可作为细胞内第二信使，这表明受体依赖性的AA释放增强可能参与神经元跨膜信号传导。为了研究这种调节反应背后的分子机制，我们现在使用转染了大鼠D2受体cDNA的中国仓鼠卵巢细胞，即CHO(D2)细胞。合成了两条与胞质型AA特异性磷脂酶A2（cPLA2）不同cDNA序列相对应的反义寡脱氧核苷酸，并将其添加到CHO(D2)细胞培养物中。用反义寡脱氧核苷酸孵育可抑制D2受体依赖性的AA释放，但对D2受体结合或D2对环磷酸腺苷积累的抑制没有影响。此外，药理学实验表明，非选择性磷脂酶抑制剂（如米帕林）可阻止D2受体依赖性的AA释放，但膜结合的非AA特异性PLA2抑制剂（如对溴苯甲酰溴）则不能。cPLA2在脑组织中表达。结果表明cPLA2参与了CHO(D2)细胞中受体依赖性的AA释放增强，这表明这种磷脂酶在大脑中可能具有类似的信号传导功能。
