Antonioli Luca, Giron Maria Cecilia, Colucci Rocchina, Pellegrini Carolina, Sacco Deborah, Caputi Valentina, Orso Genny, Tuccori Marco, Scarpignato Carmelo, Blandizzi Corrado, Fornai Matteo
Division of Pharmacology and Chemotherapy, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy.
PLoS One. 2014 Dec 30;9(12):e116253. doi: 10.1371/journal.pone.0116253. eCollection 2014.
Recent evidence indicates an involvement of P2X7 purinergic receptor (P2X7R) in the fine tuning of immune functions, as well as in driving enteric neuron apoptosis under intestinal inflammation. However, the participation of this receptor in the regulation of enteric neuromuscular functions remains undetermined. This study was aimed at investigating the role of P2X7Rs in the control of colonic motility in experimental colitis.
Colitis was induced in rats by 2,4-dinitrobenzenesulfonic acid. P2X7R distribution was examined by immunofluorescence analysis. The effects of A804598 (selective P2X7R antagonist) and BzATP (P2X7R agonist) were tested on contractions of longitudinal smooth muscle evoked by electrical stimulation or by carbachol in the presence of tetrodotoxin.
P2X7Rs were predominantly located in myenteric neurons, but, in the presence of colitis, their expression increased in the neuromuscular layer. In normal preparations, A804598 elicited a negligible increase in electrically induced contractions, while a significant enhancement was recorded in inflamed tissues. In the presence of Nω-propyl-L-arginine (NPA, neuronal nitric oxide synthase inhibitor) the A804598 effects were lost. P2X7R stimulation with BzATP did not significantly affect electrical-induced contractions in normal colon, while a marked reduction was recorded under inflammation. The inhibitory effect of BzATP was antagonized by A804598, and it was also markedly blunted by NPA. Both P2X7R ligands did not affect carbachol-induced contractions.
The purinergic system contributes to functional neuromuscular changes associated with bowel inflammation via P2X7Rs, which modulate the activity of excitatory cholinergic nerves through a facilitatory control on inhibitory nitrergic pathways.
近期证据表明，P2X7嘌呤能受体（P2X7R）参与免疫功能的精细调节，以及在肠道炎症时促使肠神经元凋亡。然而，该受体在肠神经肌肉功能调节中的作用仍未明确。本研究旨在探讨P2X7R在实验性结肠炎中对结肠运动控制的作用。
用2,4 - 二硝基苯磺酸诱导大鼠结肠炎。通过免疫荧光分析检测P2X7R的分布。在存在河豚毒素的情况下，测试A804598（选择性P2X7R拮抗剂）和BzATP（P2X7R激动剂）对电刺激或卡巴胆碱诱发的纵行平滑肌收缩的影响。
P2X7R主要位于肌间神经丛神经元，但在结肠炎存在时，其在神经肌肉层的表达增加。在正常标本中，A804598对电诱发收缩的增加可忽略不计，而在炎症组织中则记录到显著增强。在存在Nω-丙基-L-精氨酸（NPA，神经元型一氧化氮合酶抑制剂）时，A804598的作用消失。用BzATP刺激P2X7R在正常结肠中对电诱发收缩无显著影响，而在炎症状态下则记录到明显降低。BzATP的抑制作用被A804598拮抗，并且也被NPA显著减弱。两种P2X7R配体均不影响卡巴胆碱诱发的收缩。
嘌呤能系统通过P2X7R促成与肠道炎症相关的功能性神经肌肉变化，P2X7R通过对抑制性一氧化氮能途径的促进性控制来调节兴奋性胆碱能神经的活性。
