Effect of methane on P2X 7R/NLRP3 signaling pathway during inflammatory responses in a rat model of spinal cord ischemia-reperfusion / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effect of methane on purinergic ion channel type 7 receptor (P2X 7R)/nod-like receptor protein 3 (NLRP3) signaling pathway during inflammatory responses in a rat model of spinal cord ischemia-reperfusion (I/R). Methods:Fifty-four clean-grade healthy male Sprague-Dawley rats, aged 3 months, weighing 350-380 g, were divided into 3 groups ( n=18 each) using a random number table method: sham operation group (group S), spinal cord I/R group (group I/R) and methane group (group M). Rats underwent sham operation in group S. Spinal cord ischemia was induced by occlusion of the thoracic aorta combined with controlled hypotension for 9 min, followed by reperfusion in anesthetized animals in group I/R.Methane-rich saline 10 mg/kg was intraperitoneally administered immediately after onset of reperfusion in group M. Motor sensory deficit index (MSDI) in hind limbs was measured at 12, 24 and 48 h of reperfusion.The L 3-5 segment of spinal cord was removed at 48 h of reperfusion for determination of the number of normal neurons (by Nissl staining), the number of activated microglia and expression of P2X 7R, NLRP3, apoptosis-associated speck-like protein containing CARD (ASC), cysteine-requiring aspartate protease (caspase-1), interleukin-1beta (IL-1β) and IL-18 (by immunofluorescence staining) in anterior and posterior horns of spinal cord. Results:Compared with group S, the MSDI was significantly increased at 12, 24 and 48 h of reperfusion, and the number of normal neurons in anterior and posterior horns of spinal cord was decreased, the number of activated microglia was increased, and the expression of P2X 7R, NLRP3, ASC, caspase-1, IL-1β and IL-18 was up-regulated at 48 h of reperfusion in group I/R ( P<0.01). Compared with group I/R, the MSDI was significantly decreased at each time point of reperfusion, and the number of normal neurons in anterior and posterior horns of spinal cord was increased, the number of activated microglia was decreased, and the expression of P2X 7R, NLRP3, ASC, caspase-1, IL-1β and IL-18 was down-regulated at 48 h of reperfusion in group M ( P<0.05). Conclusion:The mechanism by which methane reduces inflammatory responses is related to inhibiting P2X7R/NLRP3 signaling pathway in a rat model of spinal cord I/R.