Objective To evaluate the effect of dexmedetomidine on the expression of c-fos protein in the dorsal root ganglion neurons in a rat model of neuropathic pain (NP).Methods Seventy-two adult male SpragueDawley rats,weighing 180-240 g,were randomly divided into 3 groups (n =24 each) using a random number table:sham operation group (group S),group NP,and dexmedetomidine group (group Dex).The animals were anesthetized with intraperitoneal 10％ chloral hydrate 350 mg/kg.The right sciatic nerve was exposed and 4 loose ligatures were placed on the sciatic nerve at 1 mm intervals with 4-0 silk thread in NP and Dex groups.In group Dex,dexmedetomidine 50μg/kg was injected intraperitoneally once a day starting from the end of operation until the animals were sacrificed.The equal volume of normal saline was given instead of dexmedetomidine in S and NP groups.The mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured at 1 day before ligation (T0,baseline) and 3,7 and 14 days after ligation (T1-3).Eight animals were sacrificed after measurement of pain threshold at T13 and the dorsal root ganglions of the lumbar segments (L44) were removed for detection of c-fos expression (by immuno-histochemistry).Results Compared with group S,MWT was significantly decreased,TWL was shortened,and the expression of c-fos protein was up-regulated at T1-3 in NP and Dex groups.Compared with NP group,MWT was significantly increased,TWL was prolonged,and the expression of c-fos protein was down-regulated at T1-3 in Dex group.Conclusion Dexmedetomidine can inhibit upregulation of c-fos protein expression,thus attenuating NP in rats.

Objective:To evaluate the optimization strategy of labor analgesia in obese parturients using dural puncture epidural (DPE) combined with programmed intermittent epidural bolus (PIEB).Methods:Eighty American Society of Anesthesiologists Physical Status classification Ⅰ or Ⅱ obese primiparae, who were at full term with a singleton fetus in vertex presentation, aged 20-40 yr, with body mass index of 30-40 kg/m 2, at 37-42 week gestation, with cervical dilation of 2-5 cm, and with visual analogue scale score ≥50 mm, were divided into 2 groups ( n=40 each) using a random number table method: DPE plus PIEB group (DPEP group) and DPE plus continuous epidural infusion group (DPEC group). All parturients received DPE labor analgesia, and parturients received PIEB (DPEP group) and continuous epidural infusion (DPEC group) to maintain analgesia during labor. In DPEP group, the patient-controlled epidural analgesia pump was set up to deliver a 5 ml bolus dose with a 20-min lockout interval and background infusion at 2 ml/12 min after an initial dose of 8 ml. In DPEC group, the patient-controlled epidural analgesia pump was set up to deliver a 5 ml bolus dose with a 20-min lockout interval and background infusion at 10 ml/h after an initial dose of 8 ml. The analgesia solution contained 0.1% ropivacaine plus 0.3 μg/ml sufentanil. The time to achieve adequate analgesia, consumption of ropivacaine per unit time, height of sensory block at the thoracic vertebral level, modified Bromage score, effective pressing times of patient-controlled analgesia, the number of rescue analgesia, Apgar score, delivery mode, occurrence of adverse reactions and maternal satisfaction with labor analgesia were recorded. Results:Compared with DPEC group, the time to achieve adequate analgesia was significantly shortened, the consumption of ropivacaine per unit time was decreased, and the number of rescue analgesia and effective pressing times of patient-controlled analgesia were decreased in DPEP group ( P<0.05). There were no significant differences in the height of sensory block at the thoracic vertebral level, modified Bromage score, Apgar score, delivery mode, incidence of adverse reactions and maternal satisfaction with labor analgesia between the two groups ( P>0.05). Conclusions:DPE combined with PIEB offers faster onset and better effect and achieves a greater local anesthetics-sparing effect when used for labor analgesia in obese parturients.