Role of S1PR1 in dorsal root ganglion in remifentanil-induced hyperalgesia in rats with incisional pain / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of sphingosine-1-phospho-1 receptor(S1PR1)in the dorsal root ganglion in remifentanil-induced hyperalgesia in rats with incisional pain.Methods:Forty-eight male Sprague-Dawley rats with successful intrathecal and caudal vein catheterization, weighing 260-280 g, aged 2-3 months, were divided into 6 groups ( n= 8 each) using a random number table method: control group (group C), S1PR1 antagonist (FTY720) group (group F), remifentanil group (group R), remifentanil + S1PR1 antagonist (FTY720) group (group R+ F), remifentanil + incisional pain group (group R+ I), and remifentanil + incisional pain + S1PR1 antagonist (FTY720) group (group R+ I+ F). In C group, normal saline 0.1 μg·kg -1·min -1 was intravenously infused for 60 min. In R group, remifentanil 1.0 μg· kg -1·min -1 was infused for 60 min through the caudal vein. In F group, FTY720 3 nmol was intrathecally injected, and 10 min later normal saline 1.0 μg· kg -1·min -1 was infused for 60 min via the caudal vein. In R+ F group, FTY720 3 nmol was intrathecally injected, and 10 min later remifentanil 1.0 μg· kg -1·min -1 was infused for 60 min through the caudal vein. In R+ I group, remifentanil 1.0 μg·kg -1·min -1 was infused for 60 min through the caudal vein while the model of incisional pain was developed. In R+ I+ F group, FTY720 3 nmol was intrathecally injected, 10 min later the incisional pain model was prepared, and remifentanil 1.0 μg·kg -1·min -1 was injected for 60 min through the caudal vein at the same time. The mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured at 24 h before remifentanil or normal saline infusion (T 0) and 2, 6, 24 and 48 h after stopping remifentanil or normal saline infusion (T 1-4). Rats were sacrificed after the last measurement of pain threshold, and the L 4-6 segments of dorsal root ganglion were taken for determination of the expression of S1PR1, NOD-like receptor thermal protein domain-associated protein 3 (NLRP3), interleukin-1β (IL-1β) and glutamate transporter-1 (GLT-1) protein and mRNA (by Western blot and quantitative polymerase chain reaction). Results:Compared with C group, the MWT was significantly decreased and TWL was shortened at T 1-4, the expression of S1PR1, NLRP3 and IL-1β protein and mRNA in dorsal root ganglion was up-regulated, and the expression of GLT-1 protein and mRNA in dorsal root ganglion was down-regulated in R group ( P<0.05), and no significant change was found in the parameters mentioned above in group F ( P>0.05). Compared with R group, MWT was significantly decreased and TWL was shortened at T 1-4, the expression of S1PR1, NLRP3 and IL-1β protein and mRNA in dorsal root ganglion was up-regulated, and GLT-1 protein and mRNA expression in dorsal root ganglion was down-regulated in R+ I group, and MWT was significantly increased and TWL was prolonged at T 1-4, the expression of S1PR1, NLRP3 and IL-1β protein and mRNA in the dorsal root ganglion was down-regulated, and GLT-1 protein and mRNA expression in the dorsal root ganglion was up-regulated in R+ F group ( P<0.05). Compared with R+ I group, MWT was significantly increased and TWL was prolonged at T 1-4, the expression of S1PR1, NLRP3 and IL-1β protein and mRNA in the dorsal root ganglion was down-regulated, and the expression of GLT-1 protein and mRNA in the dorsal root ganglion was up-regulated in R+ I+ F group( P<0.05). Conclusions:The mechanism by which remifentanil induces hyperalgesia is associated with up-regulation of S1PR1 expression, activation of inflammatory factors, and down-regulation of GLT-1 expression in the rats with incisional pain.