Effects of Intrathecal Injection of Opioid Compound with Low-Dose Naloxone on Pain Behavior and Blood Motilin in a Rat Model of Incisional Pain / 天津医药

ABSTRACT

Objective To investigate effects of intrathecal injection of morphine and fentanyl combined with low-dose naloxone on the pain behavior and the expression of blood motilin (MTL) in the rat model of incisional pain.Meth?ods A total of 72 healthy male Sprague-Dawley rats (weight 180-220 g), successfully intrathecally catheterized, were ran?domly divided into 6 groups (n=12 )normal saline group (NS group), incisional pain group (P group), morphine (5μg/kg)+fentanyl (0.25μg/kg) group (MFP group), morphine+fentanyl+naloxone (0.2 ng/kg, 1 ng/kg, 5 ng/kg) group (MFPN1, MF?PN2 and MFPN3 groups). All groups except NS group were made the model of incisional pain on the right plantar surface. At 24-hours before intrathecal cathetherization (T0), 24-hours before modelling (T1), 1-hours (T2), 3-hours (T3) , 6-hours (T4), 24-hours (T5) , 48-hours (T6) and 72-hours (T7) after modelling respectively, paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were detected in right hind paw in 6 rats of each group. The other 6 rats in each group were sacrificed 6-hour after operation. The plasma expression of motilin was detected by ELISA. Re?sults Compared with NS group, the PWMT was not significantly different in all time points in MFPN2 group. The values of PWTL were significantly longer at T2 and T5 in MFPN2 group than those of NS group (P0.05).Conclusion In the rat model of incision?al pain, intrathecal injection of naloxone at 1 ng/kg can inhibit the down-regulation of blood motillin caused by morphine and fentanyl, and which can up-regulate the PWTL, enhancing the analgesic effects of opioids.