To evaluate the effect of remifentanil on iron metabolism in spinal dorsal horn neurons of rats.

The primary spinal dorsal horn neurons of rats were seeded in the culture plate at a density of 2×10⁵ cells/well and divided into 4 groups using a random number table method: control group (C group, n=40), remifentanil group (R group, n=40), divalent metal transporter 1 without iron-responsive element [DMT1(-)IRE] siRNA group (siRNA group, n=32) and DMT1(-)IRE siRNA plus remifentanil group (siRNA+ R group, n=32). siRNA and siRNA+ R groups were subjected to DMT1(-)IRE siRNA transfection on day 3 of culture.R and siRNA+ R groups were incubated for 60 min in the solution with remifentanil at a final concentration of 40 nmol/L.The contents of reactive oxygen species (ROS) and Fe²⁺ were determined by fluorescent probe method, the malondialdehyde(MDA)content was detected by TBA method, and the content of labile iron pool (LIP) was detected by calcein AM and iron chelator at the end of incubation with remifentanil in R and siRNA+ R groups and at the corresponding time points in the other groups.The expression of DMT1(-)IRE and DMT1(+ )IRE was determined by Western blot in C and R groups.

Compared with C group, the expression of DMT1(-)IRE in the spinal dorsal horn neurons was significantly up-regulated, the contents of Fe²⁺, LIP, ROS and MDA were increased (P<0.05), and no significant change was found in the expression of DMT1(+ )IRE in R group (P>0.05). Compared with R group, the contents of Fe²⁺, LIP, ROS and MDA in the spinal dorsal horn neurons were significantly decreased in siRNA+ R group (P<0.05).

Remifentanil increases the iron content of spinal dorsal horn neurons by activating DMT1(-)IRE, which may be associated with the mechanism of remifentanil-induced postoperative hyperalgesia in rats.

Piperidines; Hyperalgesia; Iron; Spinal cord