Division of Pharmacology and Chemotherapy, Department of Internal Medicine, University of Pisa, Pisa, Italy.
Eur J Pharmacol. 2011 Jan 15;650(2-3):639-49. doi: 10.1016/j.ejphar.2010.10.041. Epub 2010 Oct 27.
This study investigated the expression of A(1) and A(2A) receptors in the rat colonic neuromuscular compartment, and characterized their roles in the control of motility during inflammation. Colitis was induced by 2,4-dinitrobenzenesulfonic acid. A(1), A(2A) receptors, and ecto-5'-nucleotidase (CD73, adenosine producing enzyme) mRNA expression was examined by RT-PCR. The effects of DPCPX (A(1) receptor antagonist), CCPA (A(1) receptor agonist), 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (A(2A) receptor antagonist), 4-[2-[[6-amino-9-(N-ethyl-b-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzenepropanoic acid hydrochloride (A(2A) receptor agonist), AOPCP (CD73 inhibitor) were tested on electrically or carbachol-evoked contractions in colonic longitudinal muscle preparations. In normal colon, RT-PCR revealed the presence of A(1) receptors, A(2A) receptors and CD73, and an increased expression of A(2A) receptors and CD73 was detected in inflamed tissues. In normal colon, DPCPX or 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol enhanced electrically-induced contractions, while in inflamed preparations the effect of DPCPX no longer occurred. In normal colon, CCPA or 4-[2-[[6-amino-9-(N-ethyl-b-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl] benzenepropanoic acid hydrochloride decreased electrically-induced contractions. Under inflammation, 4-[2-[[6-amino-9-(N-ethyl-b-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl] benzenepropanoic acid hydrochloride reduced electrically evoked contractions with higher efficacy, while the inhibition by CCPA remained unchanged. A(1) and A(2A) receptor ligands did not affect carbachol-induced contractions. AOPCP enhanced electrically-induced contractions and prevented the contractile effects of 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol, without interfering with DPCPX, both in normal and inflamed colons. These results indicate that, in normal colon, both A(1) and A(2A) receptors contribute to the inhibitory control of motor functions at neuronal level. Under bowel inflammation, A(1) receptor loses its modulating actions, while the recruitment of A(2A) receptor by CD73-dependent endogenous adenosine drives an enhanced inhibitory control of colonic neuromotility.
本研究旨在探讨大鼠结肠肌间神经丛中 A(1)和 A(2A)受体的表达，并阐明其在炎症期间运动控制中的作用。采用 2,4-二硝基苯磺酸诱导结肠炎。通过 RT-PCR 检测 A(1)、A(2A)受体和外核苷酸酶 (CD73，产生腺苷的酶)mRNA 的表达。测试了 DPCPX(A(1)受体拮抗剂)、CCPA(A(1)受体激动剂)、4-(2-[[6-氨基-9-(N-乙基-β-D-核糖呋喃尿苷酰基)氨基]-9H-嘌呤-2-基]氨基)乙基)苯丙酸盐酸盐(A(2A)受体拮抗剂)、4-[2-[[6-氨基-9-(N-乙基-β-D-核糖呋喃尿苷酰基)氨基]-9H-嘌呤-2-基]氨基]乙基)苯丙酸盐酸盐(A(2A)受体激动剂)、AOPCP(CD73 抑制剂)对结肠纵行肌标本的电或卡巴胆碱诱发收缩的影响。在正常结肠中，RT-PCR 显示存在 A(1)受体、A(2A)受体和 CD73，并且在炎症组织中检测到 A(2A)受体和 CD73 的表达增加。在正常结肠中，DPCPX 或 4-(2-[[6-氨基-9-(N-乙基-β-D-核糖呋喃尿苷酰基)氨基]-9H-嘌呤-2-基]氨基)乙基)苯丙酸盐酸盐增强电诱导的收缩，而在炎症制剂中，DPCPX 的作用不再发生。在正常结肠中，CCPA 或 4-[2-[[6-氨基-9-(N-乙基-β-D-核糖呋喃尿苷酰基)氨基]-9H-嘌呤-2-基]氨基]乙基)苯丙酸盐酸盐降低电诱导的收缩。在炎症状态下，4-[2-[[6-氨基-9-(N-乙基-β-D-核糖呋喃尿苷酰基)氨基]-9H-嘌呤-2-基]氨基]乙基)苯丙酸盐酸盐以更高的疗效降低电诱发的收缩，而 CCPA 的抑制作用保持不变。A(1)和 A(2A)受体配体不影响卡巴胆碱诱导的收缩。AOPCP 增强电诱导的收缩，并防止 4-(2-[[6-氨基-9-(N-乙基-β-D-核糖呋喃尿苷酰基)氨基]-9H-嘌呤-2-基]氨基)乙基)苯丙酸盐酸盐的收缩作用，而不干扰 DPCPX，在正常和炎症结肠中均如此。这些结果表明，在正常结肠中，A(1)和 A(2A)受体均有助于神经元水平运动功能的抑制性控制。在肠道炎症下，A(1)受体失去其调节作用，而 CD73 依赖性内源性腺苷募集的 A(2A)受体驱动对结肠神经运动的增强抑制性控制。
