Objective To evaluate the role of neuron-restrictive silencer factor (NRSF) in the spinal cord in remifentanil-induced hyperalgesia in a mouse model of incisional pain (IP) .Methods Fifty-six male Kunming mice were randomly divided into 7 groups (n=8 each):control group (group C) ,IP group (group I) ,IP +remifentanil group (group IR ) , NRSF antisense oligonucleotide group (NAS group ) , IP + NRSF antisense oligonucleotide group (I+NAS group ) ,IP + remifentanil + NRSF mismatch oligonucleotide group (IR+NMS group) , and IP + remifentanil + NRSF antisense oligonucleotide group (IR + NAS group ) . Artificial cerebrospinal fluid 5 μl was injected intrathecally once a day for 3 consecutive days in C ,I and IR groups .NRSF antisense oligonucleotide NAS 10μg was injected intrathecally once a day for 3 consecutive days in NAS ,I+NAS and IR + NAS groups . NRSF mismatch oligonucleotide 10 μg was injected intrathecally once a day for 3 consecutive days in IR+NMS group .A 1-cm longitudinal incision was made through skin ,fascia and muscle of the plantar aspect of the right hindpaw to establish the model of incisional pain in sevoflurane-anesthetized rats .At 30 min after the last injection ,normal saline 0.4 ml was infused subcutaneously in C and NAS groups ,the model was established and normal saline 0.4 ml was subcutaneously infused simultaneously in I and I+NAS groups ,and the model was established and remifentanil 0.04 mg/kg was subcutaneously infused simultaneously in IR ,IR+NMS and IR+NAS groups .At 3 days before operation (T0 ) ,4 h before operation (T1 ) and 4 ,12 ,24 and 48 h after operation (T1-5 ) ,mechanical paw withdrawal threshold to von Frey stimuli (PMWT ) and paw withdrawal latency to thermal nociceptive stimulus (PTWL ) were measured .Results Compared with C group ,the PWMT and PWTL were significantly decreased at T2-5 in I ,IR ,I+NAS ,IR+NMS and IR+NAS groups ( P<0.05) ,and no significant change was found in the PWMT and PWTL at each time point in NAS group ( P>0.05 ) .Compared with I group ,the PWMT and PWTL were significantly decreased at T2-5 in IR and IR+NMS groups ( P<0.05) , and no significant change was found in the PWMT and PWTL at each time point in I +NAS group ( P>0.05) . Compared with IR group ,no significant change was found in the PWMT and PWTL at each time point in IR+NMS group ( P>0.05) ,and the PWMT and PWTL were significantly increased at T2-5 in IR+NAS group ( P<0.05) . Conclusion NRSF in the spinal cord is involved in the development and maintenance of hyperalgesia induced by remifentanil in a mouse model of IP .

OBJECTIVE: To determine the changes of Mu-opioid receptor (Mor) and neuron-restrictive silencer factor (NRSF) in periaquductal gray (PAG) in mouse models of remifentanil-induced postoperative hyperalgesia. METHODS: Thirty-two Kun-Ming mice were randomly divided into 4 groups (8 mice in each group): Group C (mice underwent a sham procedure and saline was infused subcutaneously over a period of 30 min), Group I (mice underwent a surgical incision and the same volume of saline), Group R (mice underwent a sham procedure and remifentanil was infused subcutaneously at the moment of surgical incision over a period of 30 min), and group IR (mice underwent a surgical incision and remifentanil). Paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) tests were performed 24 h before the operation and 2, 6, 24, and 48 h after the operation. The specimens were collected after behavioral testings at 48 h. The expressions of Mor and NRSF in mice's PAG neurons were determined by Western blot. RESULTS: Mechanical allodynia and thermal hyperalgesia developed in Group I, R and IR (P<0.01). Intraoperative infusion of remifentanil enhanced mechanical allodynia and thermal hyperalgesia in mice with planta incision (P<0.01). In Group R and Group IR, the expression of Mor was significantly lower (P<0.01) and NRSF was significantly higher (P<0.01) when compared with Group C and Group I. CONCLUSION Intraoperative infusion of remifentanil induces postoperative hyperalgesia in mouse models, accompanied with decreased expressions of Mor and increased of NRSF level in PAG neurons, which may be involved in remifentanil induced hyperalgesia.
Animals ; Disease Models, Animal ; Hyperalgesia ; chemically induced ; Mice ; Pain, Postoperative ; Periaqueductal Gray ; drug effects ; metabolism ; Piperidines ; administration & dosage ; Receptors, Opioid, mu ; metabolism ; Remifentanil ; Repressor Proteins ; metabolism