Adenosine A1 receptor-mediated inhibition of protein kinase A-induced calcitonin gene-related peptide release from rat trigeminal neurons
Adenosine A1 receptor-mediated inhibition of protein kinase A-induced calcitonin gene-related peptide release from rat trigeminal neurons
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DOI：
10.1124/mol.59.6.1533
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发表时间：
2001-06-01
影响因子：
3.6
通讯作者：
Humphrey, PPA
中科院分区：
文献类型：
--
作者：
Carruthers, AM;Sellers, LA;Humphrey, PPA
降钙素基因相关肽（CGRP）是一种强有力的血管扩张剂，与偏头痛的发病机制有关。用毛喉素激活腺苷酸环化酶可显著增加培养的成年大鼠三叉神经元的cAMP释放。用一些已知对cAMP生成有抑制作用的药物对这种分泌的调节进行了研究，这些药物通过受体偶联G（i/o）蛋白介导cAMP生成。值得注意的是，毛喉素刺激的CGRP释放可能与蛋白激酶A（PKA）底物环AMP反应元件结合蛋白（CREB）的磷酸化密切相关。腺苷A（1）受体选择性激动剂GR 79236 X可有效抑制毛喉素刺激的CGRP释放（pIC（50）= 7.7 +/- 0.1，300 nM时最大抑制65 +/- 2.5%），而A（2A）（CGS 21680）和A（3）（2-氯-N-6-（3-碘苄基）-腺苷-5 ′-N-甲基脲酰胺）受体选择性激动剂没有作用。GR 79236 X介导的抑制作用被A（1）受体拮抗剂8-环戊基-1，3-二丙基黄嘌呤消除。免疫细胞化学研究和Western分析显示三叉神经元上存在腺苷A（1）受体。然而，尽管在这些细胞上额外检测到5-羟色胺（5-HT）（1B）受体，但临床有效的抗偏头痛5-HT 1B/1D激动剂舒马曲坦既不抑制毛喉素刺激的CGRP释放，也不对伴随的CREB磷酸化产生任何影响。相比之下，μ阿片激动剂芬太尼引起CGRP水平降低74 +/-4%。毛喉素刺激的CGRP释放和CREB磷酸化可通过将细胞与氯苯硫基-cAMP孵育来模拟，并通过PKA抑制剂myrPKI预处理来阻断（14-22）。总之，目前的数据证实了毛喉素刺激CGRP释放的PKA依赖性，并表明A（1）腺苷激动剂可能需要在偏头痛和神经源性炎症模型中进行进一步研究。
Calcitonin gene-related peptide (CGRP), a potent vasodilator, has been implicated in the pathogenesis of migraine. Its release from adult rat trigeminal neurons in culture was shown to be markedly increased by the activation of adenylate cyclase with forskolin, Modulation of this secretion was investigated by a number of agents with known inhibitory effects on cAMP generation mediated via receptor coupling to G(i/o) proteins. Significantly, forskolin-stimulated CGRP release could be closely correlated with the phosphorylation of the protein kinase A (PKA) substrate cyclic AMP response element-binding protein (CREB). Forskolin-stimulated CGRP release could be potently and effectively inhibited by the adenosine A(1) receptor-selective agonist GR79236X (pIC(50) = 7.7 +/- 0.1, maximal inhibition 65 +/- 2.5% at 300 nM), whereas the A(2A) (CGS21680) and the A(3) (2-chloro-N-6-(3-iodobenzyl)- adenosine-5'-N-methyluronamide) receptor-selective agonists were without effect. GR79236X-mediated inhibition was abolished by the A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine. Immunocytochemical studies and Western analysis revealed the presence of adenosine A(1) receptors on trigeminal neurons. However, despite the additional detection of 5-hydroxytryptamine (5-HT)(1B) receptors on these cells, the clinically effective antimigraine 5-HT1B/1D agonist sumatriptan did not inhibit forskolin-stimulated CGRP release nor did it show any effect on the concomitant CREB phosphorylation. In contrast, the mu -opioid agonist fentanyl elicited a 74 +/- 4% reduction in CGRP levels. Forskolin-stimulated CGRP release and CREB phosphorylation could be mimicked by incubation of the cells with chlorophenylthio-cAMP and blocked by pretreatment with the PKA inhibitor myrPKI(14-22). Taken together, the present data confirm the PKA-dependence of forskolin-stimulated CGRP release and suggest that A(1) adenosine agonists may warrant further investigation in models of migraine and neurogenic inflammation.