Objective To evaluate the role of spinal κ-opioid receptors in remifentanil-induced postoperative central sensitization in a rat model of incisional pain by in vivo electrophysiology.Methods Sixty adult male Sprague-Dawley rats in which intrathecal catheters were successfully implanted,weighing 230-270 g,were divided into 5 groups (n=12 each) using a random number table:control group (group C),incisional pain group (group I),remifentanil group (group R),remifentanil plus incisional pain group (group R+I),and κ-opioid receptor agonist U50488H group (group U).A 1 cm longitudinal incision was made through skin,fascia and muscle of the plantar aspect of the right hind paw in isofiurane-anesthetized rats to establish the model of incisional pain.Remifentanil was intravenously infused for 1 h at a rate of 10 μg · kg 1 · min-1 in group R.In group R+I,remifentanil was intravenously infused for 1 h at a rate of 10 μg · kg-1 · min 1,and the model of incisional pain was established at the same time.In group U,U50488H 10 μg/10μl was injected intrathecally,30 min later remifentanil was intravenously infused for 1 h at a rate of 10 μg · kg-1 · min-1,and the model of incisional pain was established.Six rats in each group were randomly selected,the mechanical pain threshold (MPT) was measured in bilateral hind paws before implanting intrathecal catheter (T0),before operation (T1),and at 1 h,4 h and 1,2 and 3 clays after operation (T2-6).Six rats in each group were randomly selected to record the C fiber-evoked filed potentials in the spinal dorsal horn from 60 min before administration or operation to 180 min after administration or operation,the long-term potentiation (LTP) induced was also recorded,and the area under the curve (AUC) of C-fiber-evoked field potentials was calculated.Results No LTP was recorded in C,I and U groups,and the LTP was recorded in R and R+I groups.Compared with group C,the MPT in bilateral hind paws at T5,6 was significantly decreased in group R,the MPT in ipsilateral hind paws at T2 6 was decreased in group I,the MPT in ipsilateral hind paws at T2-6 and in contralateral hind paws at T5,6 was decreased in group R+I,the MPT in ipsilateral hind paws at T2-4 was decreased in group U,and the AUC of C-fiber-evoked field potentials was increased in R and R+I groups (P＜0.05).Compared with group Ⅰ,the MPT in ipsilateral hind paws at T4-6 and in contralateral hind paws at T5,6 was significantly decreased,and the AUC of C-fiber-evoked field potentials was increased in group R+I (P＜0.05).Compared with group R+ I,the MPT in ipsilateral hind paws at T2-6 and in contralateral hind paws at T5,6 was significantly increased,and the AUC of C-fiber-evoked field potentials was decreased in group U (P＜0.05).Conclusion The results of in vivo electrophysiology confirm that inhibition of spinal κ-opioid receptor function mav be involved in the mechanism by which remifentanil induces postoperative central sensitization in a rat model of incisional pain.

Objective To compare the effects of propofol-based anesthesia versus sevoflurane-based anesthesia on postoperative cognitive dysfunction (POCD) in elderly patients with metabolic syndrome.Methods Ninety-four patients of both sexes,aged 65-80 yr,weighing 60-95 kg,of American Society of Anesthesiologists physical status Ⅱ or Ⅲ,scheduled for elective orthopedic surgery or gastrointestinal surgery under general anesthesia,were assigned to either propofol-based anesthesia group (group P,n =47) or sevoflurane-based anesthesia group (group S,n =47) using a random number table.Anesthesia was maintained by Ⅳ infusion of propofol 4-6 mg · kg-1 · h-1 in group P and by inhalation of 1％-2％ sevoflurane in group S.The bispectral index value was maintained between 40-60 during surgery.Cognitive function was evaluated using the Mini-Mental State Examination,trial making test and Digit Span Tests Forward and Backward at 1 day before surgery and 3 and 7 days after surgery.The occurrence of POCD was recorded at 3 and 7 days after surgery.Results There were no significant differences in Mini-Mental State Examination scores,trial making test time,Digit Span Tests Forward and Backward scores or incidence of POCD between group S and group P (P＞0.05).Conclusion The effects of propofol-based anesthesia and sevoflurane-based anesthesia on POCD are comparable in elderly patients with metabolic syndrome.

Objective To explore the changes of cerebral local neuronal spontaneous activity between heroin dependent individuals and normal controls.Methods 3.0 T MRI were used for data acquisition,fMRI data were acquired during resting state from 20 male heroin dependent individuals(HD)and 1 5 matched normal controls(NC),and then the difference of amplitude of low frequency fluctuation (ALFF)between groups were analysised.Results Compared with NC,ALFF in rostral cingulated zone(bilateral anteri-or cingulate cortex ,medial prefrontal cortex )was significantly reduced in HD.Conclusion Dysfunction of resting state in RCZ were observed in HD,which may result in cognitive impairment and plays an important role in the transitions from ideas into behav-ior of relapse in addiction.