Objective:To evaluate the relationship between intracerebroventricular glial cell line-derived neurotrophic factor (GDNF)-induced improvement in long-term postoperative cognitive function and expression of PKMζ and Kalirin in the hippocampus of neonatal rats.Methods:Sixty 7-day old Sprague-Dawley rats, male or female, were divided into 4 groups ( n=15 each) using a random number table method: control group (group C), GDNF group (group G), surgery group (group S) and surgery plus GDNF group (group S+ G). Group C did not receive anesthesia, surgery or drug treatment. Group G received intracerebroventricular injection of 0.3 μg recombinant rat GDNF. Group S and group S+ G underwent right carotid artery exposure surgery under 3% sevoflurane anesthesia, and in addition group S+ G received intracerebroventricular injection of GDNF. The Barnes maze test and the fear conditioning test were performed starting from postnatal day 33. The animals were then sacrificed under sevoflurane anesthesia after behavioral testing, the brains were obtained and divided into 2 halves sagittally along the midline. The left half of the brain was used for Golgi staining to observe dendritic morphology and measure dendritic spine density. The hippocampal protein was extracted from the right half of the brain to detect the expression of PKMζ and Kalirin by Western blot. Results:Compared with group C, the time to identify the target box in the Barnes maze test was significantly prolonged, the context-related freezing time in the fear conditioning test was shortened, the total dendritic length, the number of branches, the number of intersections in sholl analysis and spinal density in the hippocampus were reduced, and the expression of PKMζ and Kalirin was down-regulated in group S ( P<0.05), and no significant change was found in the aforementioned parameters in group G ( P>0.05). Compared with group S, the time to identify the target box in the Barnes maze test was significantly shortened, the context-related freezing time in the fear conditioning test was prolonged, the total dendritic length, the number of branches, the number of intersections in sholl analysis and spinal density in the hippocampus were increased, and the expression of PKMζ and Kalirin was up-regulated in group S+ G ( P<0.05). Conclusions:The mechanism by which intracerebroventricular GDNF improves long-term postoperative cognitive function may be related to up-regulating the expression of PKMζ and Kalirin and promoting the development of dendrites and dendritic spines in the hippocampus of neonatal rats.

Objective:To evaluate the role of autophagy in hydrogen-rich solution-induced reduction of remifentanil-induced hyperalgesia in rats.Methods:Thirty-two clean-grade healthy male Sprague-Dawley rats, aged 2-3 months, weighing 240-260 g, were divided into 4 groups ( n=8 each) by a random number table method: incisional pain group (group I), remifentanil+ incisional pain group (group RI), hydrogen-rich solution+ remifentanil+ incisional pain group (group HRI), and hydrogen-rich solution + autophagy inhibitor+ remifentanil+ incisional pain group (MHRI group). The tail vein was catheterized, the equal volume of normal saline was intravenously infused for 60 min while the incisional pain model was developed in group I, and remifentanil was intravenously infused at a rate of 1 μg·kg -1·min -1 for 60 min while the incisional pain model was developed in RI, HRI and MHRI groups, hydrogen-rich solution 10 ml/kg was intraperitoneally injected at 10 min before preparing the model in group HRI, and 3-MA 15 mg/kg was intraperitoneally injected at 1 h before preparing the model in MHRI group, and the other treatments were similar to those previously described in group HRI. The mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were determined at 24 h before and 2, 6, 24 and 48 h after the end of infusion. The rats were sacrificed under anesthesia after the behavioral testing, and the lumbar enlargement segment of the spinal cord was removed for determination of the expression of microtubule-associated protein 1 light chain 3Ⅱ (LC3Ⅱ), Beclin-1 and P62 by Western blot. Results:Compared with the baseline at T 0, the MWT was significantly decreased and TWL was shortened at T 1-4 in the four groups ( P<0.05). Compared with group I, the MWT was significantly decreased and TWL was shortened at T 1-4, the expression of LC3 II and Beclin-1 was up-regulated, and the expression of P62 was down-regulated in group RI and group HRI ( P<0.05). Compared with group RI, the MWT was significantly increased and TWL was prolonged at T 1-4 in group HRI and group MHRI, the expression of LC3 II and Beclin-1 was significantly up-regulated, and the expression of P62 was down-regulated in group HRI, and the expression of LC3 II and Beclin-1 was significantly down-regulated, and the expression of P62 was up-regulated in group MHRI ( P<0.05). Compared with group HRI, the MWT was significantly decreased and TWL was shortened at T 1-4, the expression of LC3 II and Beclin-1 was down-regulated, and the expression of P62 was up-regulated in group MHRI ( P<0.05). Conclusions:The mechanism by which hydrogen-rich solution alleviates hyperalgesia may be related to enhancing the level of autophagy in the spinal cord of rats with incisional pain induced by remifentanil.

Objective:To evaluate the relationship between the mechanism of preoperative sleep deprivation aggravating postoperative cognitive dysfunction and theta oscillations in the hippocampal CA1 region in aged mice.Methods:Twenty-four SPF male C57BL/6J mice, aged 18 months, weighing 20-30 g, were divided into 3 groups ( n=8 each) by a random number table method: normal control group (group C), operation group (group S) and preoperative sleep deprivation + operation group (group SD+ S). The sleep deprivation model was established using the sleep deprivation rod method, and the sleep deprivation time was 24 h before operation. The sleep deprivation rod was set to rotate continuously at 6 rpm/min, and the direction was randomly reversed to force the mice to exercise to achieve the purpose of sleep deprivation. Group C received no treatment. Group S underwent exploratory laparotomy under isoflurane anesthesia. After sleep deprivation for 24 h, SD+ S group underwent exploratory laparotomy under isoflurane anesthesia. Y-maze and Morris water maze tests were used to evaluate postoperative cognitive function. The theta oscillations in the hippocampal CA1 region were observed and recorded by EEG electrodes in vivo. The animals were then sacrificed and brain tissues were obtained for determination of the density of dendritic spines in the hippocampal CA1 region. Results:Compared with group C, the number of crossing the original platform was significantly decreased, and the time of staying at the original platform quadrant and time of exploring the novel arm were shortened, and the number of entries into the novel arm was reduced, the density of dendritic spines in the hippocampal CA1 region was reduced, and the percentage of theta oscillation power was decreased during the Y maze test in group S ( P<0.05). Compared with S group, the number of crossing the original platform was significantly decreased, and the time of staying at the original platform quadrant and time of exploring the novel arm were shortened, and the number of entries into the novel arm was reduced, the density of dendritic spines in the hippocampal CA1 region was reduced, and the percentage of theta oscillation power was decreased during the Y maze test in SD+ S group ( P<0.01). Conclusions:The mechanisms by which preoperative sleep deprivation exacerbates postoperative cognitive dysfunction may be related to reduction in theta oscillations in the hippocampal CA1 region of aged mice.

Objective:To compare the efficacy of closed-loop target-controlled deep versus moderate neuromuscular blockade in gynecological laparoscopic surgery.Methods:This was a prospective study. Fifty American Society of Anesthesiologists Physical Status classification I or Ⅱ patients, aged 18-64 yr, with body mass index of 18-30 kg/m 2, scheduled for elective gynecological laparoscopic surgery in the General Hospital of Tianjin Medical University from March 2020 to March 2021, were allocated into 2 groups ( n=25 each) using a random number table method: closed-loop target-controlled moderate neuromuscular blockade group (group TOF) and closed-loop target-controlled deep neuromuscular blockade group (group PTC). Rocuronium was given by closed-loop target-controlled infusion in both groups. In group TOF, the target muscle relaxation was considered as train-of-four stimulation (TOF) of 1 or 2. In group PTC, the target muscle relaxation was considered as post-titanic count of 1 or 2. The score for operator′s satisfaction with muscle relaxation, grading, satisfaction rate, mean pneumo-peritoneum pressure, consumption of rocuronium, recovery index, recovery time to a TOF ratio 0.9 and time to extubation were recorded. The postoperative visual analogue scale score for abdominal pain and use of rescue analgesics were recorded, and the occurrence of complications such as shoulder pain, arm pain, nausea, vomiting and hypoxemia was also recorded within 48 h after surgery. Results:Compared with group TOF, the score for operator′s satisfaction with muscle relaxation, grading and satisfaction rate were significantly increased, the mean pneumo-peritoneum pressure was decreased, the total and average consumption of rocuronium was increased, the recovery time of a TOF ratio 0.9 was prolonged, and the postoperative visual analogue scale score for abdominal pain and usage rate of flurbiprofenate were decreased in group PTC ( P<0.05). There were no significant differences in the recovery index, tracheal extubation time or postoperative incidence of hypoxemia, shoulder pain, arm pain and nausea and vomiting between the two groups ( P>0.05). Conclusions:Compared with the closed-loop target-controlled moderate neuromuscular blockade, the closed-loop target-controlled deep neuromuscular blockade provides more satisfactory surgical conditions for gynecological laparoscopic surgery, decreases pneumoperitoneum pressure and reduces related complications, without increasing the development of postoperative adverse reactions.

Objective:To evaluate the role of sphingosine-1-phospho-1 receptor 1 (S1PR1) in remifentanil-induced hyperalgesia in rats with incisional pain and the relationship with KCNQ2/3 potassium channels in the dorsal root ganglia (DRG).Methods:Forty-eight male Sprague-Dawley rats with successful caudal vein catheterization, aged 2-3 months, weighing 260-280 g, were divided into 6 groups ( n=8 each) using a random number table method: control group (group C), S1PR1 inhibitor group (FTY720) group (group F), remifentanil group (group R), remifentanil + S1PR1 inhibitor (FTY720) group (group RF), remifentanil + incision pain group (group RI) and remifentanil + incision pain + S1PR1 inhibitor (FTY720) group (group RIF). In group C, normal saline 0.1 ml· kg -1·min -1 was intravenously infused for 60 min. In group F, FTY720 3 nmol was intrathecally injected at 10 min before normal saline injection, and 0.1 ml · kg -1·min -1 normal saline was infused into the caudal vein for 60 min. Remifentanil 1.0 μg· kg -1·min -1 was infused for 60 min through the caudal vein in group R. In RF group, FTY720 (3 nmol) was intrathecally injected, and 10 min later remifentanil 1.0 μg· kg -1·min -1 was infused via the caudal vein for 60 min. The incisional pain model was established, and remifentanil 1.0 μg· kg -1·min -1 was infused via the caudal vein for 60 min in RI group. In RIF group, FTY720 3 nmol was intrathecally injected at 10 min before remifentanil infusion, then the incisional pain model was developed, and remifentanil 1.0 μg· kg -1·min -1 was infused via the caudal vein at the same time for 60 min. The mechanical paw withdraw threshold (MWT) and thermal paw withdraw latency (TWL) were measured at 24 h before remifentanil or normal saline infusion (T 0) and 2, 6, 24 and 48 h after remifentanil or normal saline infusion (T 1-4). The rats were sacrificed after the last measurement of pain threshold, and the L 4-6 segments of the DRG were taken for determination of the expression of S1PR1, KCNQ2 and KCNQ3 protein and mRNA in the DRG by Western blot and real-time polymerase chain reaction. Results:Compared with group C, the MWT was significantly decreased, and the TWL was shortened at T 1-4, the expression of S1PR1 protein and mRNA in the DRG was up-regulated, the expression of KCNQ2 and KCNQ3 protein and mRNA in the DRG was down-regulated ( P<0.05), and no significant change was found in each parameter in R and RI groups ( P>0.05). Compared with group R, the MWT was significantly decreased, and the TWL was shortened at T 1-4, the expression of S1PR1 protein and mRNA in the DRG was up-regulated, and the expression of KCNQ2 and KCNQ3 protein and mRNA in the DRG was down-regulated in group RI, and the MWT was significantly increased, and the TWL was prolonged at T 1-4, the expression of S1PR1 protein and mRNA in the DRG was down-regulated, and the expression of KCNQ2 and KCNQ3 protein and mRNA in the DRG was up-regulated in group RF ( P<0.05). Compared with group RI, the MWT was significantly increased, and the TWL was prolonged at T 1-4, the expression of S1PR1 protein and mRNA in the DRG was down-regulated, and the expression of KCNQ2 and KCNQ3 protein and mRNA in the DRG was up-regulated in group RIF ( P<0.05). Conclusions:S1PR1 is involved in the process of remifentanil-induced hyperalgesia in rats with incisional pain, which is related to the inhibition of KCNQ2/3 potassium channel expression in the DRG.

Objective To evaluate the role of autophagy in the treatment of neuropathic pain(NP)with hydrogen-rich saline.Methods Forty adult male Sprague-Dawley rats with successful intubation were randomly divided into 5 groups(n= 8)using a random number table:the sham operation group(group S),the neuropathic pain group(group C),the hydrogen-rich saline group(group H),the autophagy inhibitor group(group M)and the hydrogen-rich saline + autophagy inhibitor group(group HM).There were 8 rats in each group.The NP model was established by chronic constriction of the sciatic nerve(CCI)in rats.The autophagy inhibitor 3-methyladenine(3-MA)was intraperitoneally injected with 30μg/kg in the group M and the group HM.The hydrogen-rich saline(0.6 mmol/L)was intraperitoneally injected with 10 mL/kg in the group H and the group HM.The other groups were intraperitoneally injected with the same amount of normal saline twice a day for 7 consecutive days.Paw withdrawal threshold to mechanical stimulation(MWT)and paw withdrawal latency to thermal stimulation(TWL)were measured at 1 day before and 1,3,5,7 and 14 days after modeling(T0-T5).After the last measurement of pain threshold,the L4-L6 segment of spinal cord was removed for determination of the expression of autophagy-related proteins microtubule-associated protein light chain 3(LC3)Ⅱ,Beclin-1 and p62 proteins by Western blot assay.The expression levels of superoxide dismutase(SOD)and malondialdehyde(MDA)in spinal cord tissue were detected.Results Compared with the group S,MWT and TWL were decreased in the group C at T2-5,the expression levels of LC3 Ⅱ,Beclin-1 and p62 were increased,SOD activity was decreased,and MDA content was increased at T5(P＜0.05).Compared with the group C,MWT and TWL were increased in the group H at T2-5,LC3 Ⅱ and Beclin-1 protein expression levels were increased,p62 protein expression levels were decreased,SOD activity was increased,and MDA content was decreased at T5(P＜0.05).MWT and TWL were decreased in the group M at T2-5,LC3 Ⅱ and Beclin-1 protein expression levels were decreased,p62 protein expression levels were increased,SOD activity was decreased,and MDA content was increased at T5(P＜0.05).Compared with the group M,MWT and TWL were increased in the group HM at T2-5,LC3 Ⅱ and Beclin-1 protein expression levels were increased,p62 protein expression levels were decreased,SOD activity was increased,and MDA content was decreased at T5(P＜0.05).Conclusion Hydrogen-rich saline can alleviate neuropathic pain and inhibit oxidative stress in spinal cord in rats,and the mechanism may be related to the increase of autophagy.

Objective:To investigate whether propofol can cause injury to hippocampal mitochondria in neonatal rats and the regulation of excitatory amino acid receptor AMPA receptor.Methods:Forty-eight Sprague-Dawley (SD) rats aged 7 days were randomly divided into control group, propofol group, propofol+AMPA receptor agonist AMPA group (propofol+AMPA group) and propofol+AMPA receptor inhibitor CNQX group (propofol+CNQX group), with 12 rats in each group. The rats in the propofol groups were intraperitoneally injected with 30 mg/kg propofol, while in control group with 3 mg/kg normal saline. Each group was given 1/2 of the first dose every 20 minutes after the first administration, three times a day, for three consecutive days. The rats in the propofol+AMPA group and the propofol+CNQX group were injected with 1 g/L AMPA or CNQX 5 μL through left ventricle after the first administration. Three days after administration, the rats were sacrificed to obtain brain tissue. Western blotting was used to determine the expression of AMPA receptor glutamate receptors (GluR1, GluR2) subunit totally (T) and on membrane (M) in hippocampus. The expression of dynamin-related protein-1 (DRP-1) and phosphorylated-DRP-1 (p-DRP-1) and mitofusin 2 (Mfn2) related to mitochondrial fission and fusion were determined. The adenosine triphosphate (ATP) content and ATPase activity were determined.Results:Compared with the control group, GluR1 expression and its M/T ratio were significantly increased after treatment of propofol, GluR2 expression and its M/T ratio were significantly decreased, the ATP content and ATP-related enzyme activity were decreased significantly, while the expression of DRP-1 and its phosphorylation was significantly increased, and the expression of Mfn2 was significantly decreased. The changes indicated that repeated intraperitoneal injection of 30 mg/kg propofol leading to the injury of mitochondria in neural cells. Compared with the propofol group, the GluR1 expression and its M/T ratio further increased after AMPA agonist administration [T-GluR1 protein (T-GluR1/β-actin): 2.41±0.29 vs. 1.72±0.11, M-GluR1 protein (M-GluR1/β-actin): 1.18±0.15 vs. 0.79±0.09, M/T ratio: 0.78±0.12 vs. 0.46±0.08, all P < 0.01], GluR2 expression was significantly increased [T-GluR2 protein (T-GluR2/β-actin): 0.65±0.13 vs. 0.30±0.14, P < 0.01; M-GluR2 protein (M-GluR2/β-actin): 0.17±0.05 vs. 0.13±0.07, P > 0.05], but its M/T ratio was further decreased (0.27±0.10 vs. 0.41±0.08, P < 0.05). The ATP-related enzyme activity was further decreased, and the ATP content was further decreased (μmol/g: 0.32±0.07 vs. 0.70±0.10, P < 0.01). Mitochondria DRP-1 expression and its phosphorylation were further increased [DRP-1 protein (DRP-1/GAPDH): 2.75±0.36 vs. 1.70±0.19, p-DRP-1 protein (p-DRP-1/GAPDH): 0.99±0.14 vs. 0.76±0.15, both P < 0.05], and Mfn2 expression was further decreased (Mfn2/GAPDH: 0.23±0.12 vs. 0.54±0.12, P < 0.05). This indicated that the AMPA agonist increased the expression of the AMPA receptor GluR1 subunit on the cell membrane and shifted the GluR2 into the cell, thus increasing the mitochondrial injury caused by propofol. Compared with the propofol group, the GluR1 expression and its M/T ratio decreased significantly after AMPA inhibitor administration [T-GluR1 protein (T-GluR1/β-actin): 0.99±0.14 vs. 1.72±0.11, M-GluR1 protein (M-GluR1/β-actin): 0.21±0.07 vs. 0.79±0.09, M/T ratio: 0.21±0.07 vs. 0.46±0.08, all P < 0.01], the change of GluR2 expression was not significant, but its M/T ratio was significantly increased (0.59±0.09 vs. 0.41±0.08, P < 0.05). The ATP-related enzyme activity was increased significantly, and the ATP content was increased significantly (μmol/g: 0.87±0.12 vs. 0.70±0.10, P < 0.05). Mitochondria DRP-1 expression and its phosphorylation were significantly decreased [DRP-1 protein (DRP-1/GAPDH): 1.18±0.17 vs. 1.70±0.19, p-DRP-1 protein (p-DRP-1/GAPDH): 0.37±0.10 vs. 0.76±0.10, both P < 0.05], and Mfn2 expression was significantly increased (Mfn2/GAPDH: 0.78±0.10 vs. 0.54±0.12, P < 0.05). This indicated that AMPA inhibitor promoted the movement to the cell membrane of GluR2 subunits meanwhile inhibited the expression of GluR1 subunits, thus alleviating the injury of mitochondrial caused by propofol in the brain. Conclusions:Repeated intraperitoneal injection of 30 mg/kg propofol for 3 days can increase the expression of GluR1 subunits of AMPA receptor in 7-day neonatal rats hippocampus mainly distributing in the cell membrane, decrease the expression of GluR2 subunits moving into the cell, thus causing injury of mitochondrial function and dynamics, which can be aggravated by AMPA receptor agonist and alleviated by AMPA receptor inhibitors.

OBJECTIVE: To investigate the effect of hydrogen gas on NOD-like receptor protein 3 (NLRP3) inflammasomes in the cerebral cortex of rats with traumatic brain injury (TBI). METHODS: 120 adult male Sprague-Dawley (SD) rates were randomly divided into 5 groups (n = 24): sham operation group (S group), TBI model group (T group), TBI+NLRP3 inhibitor MCC950 group (T+M group), TBI+hydrogen gas group (T+H group), TBI+hydrogen gas+MCC950 group (T+H+M group). TBI model was established by controlled cortical impact. NLRP3 inhibitor MCC950 (10 mg/kg) was intraperitoneally injected for 14 consecutive days before TBI operation in T+M and T+H+M groups. 2% hydrogen inhalation was given for 1 hour at 1 hour and 3 hours after TBI operation in T+H and T+H+M groups. At 6 hours after TBI operation, the pericontusional cortex tissues were obtained, the content of Evans blue (EB) was detected to evaluate the permeability of the blood-brain barrier. Water content in brain tissue was detected. The cell apoptosis was detected by TdT-mediated dUTP nick end labeling (TUNEL) and the neuronal apoptosis index was calculated. The expressions of Bcl-2, Bax, NLRP3, apoptosis-associated speck-like protein containing CARD (ASC) and caspase-1 p20 were detected by Western blotting. The levels of interleukins (IL-1β, IL-18) were detected by enzyme-linked immunosorbent assay (ELISA). RESULTS: Compared with the S group, the content of EB in cerebral cortex, water content in brain tissue, apoptosis index and the expressions of Bax, NLRP3, ASC, caspase-1 p20 in T group were significantly increased, the expression of Bcl-2 was down-regulated, the levels of IL-1β and IL-18 were increased [the content of EB (μg/g): 87.57±6.89 vs. 10.54±1.15, water content in brain tissues: (83.79±2.74)% vs. (74.50±1.19)%, apoptotic index: (62.66±5.33)% vs. (4.61±0.96)%, Bax/β-actin: 4.20±0.44 vs. 1, NLRP3/β-actin: 3.55±0.31 vs. 1, ASC/β-actin: 3.10±0.26 vs. 1, caspase-1 p20/β-actin: 3.28±0.24 vs. 1, Bcl-2/β-actin: 0.23±0.03 vs. 1, IL-1β (ng/g): 221.58±19.15 vs. 27.15±3.27, IL-18 (ng/g): 87.26±7.17 vs. 12.10±1.85, all P < 0.05]. Compared with the T group, the T+M, T+H and T+H+M groups had significant reductions in the content of EB and water content in brain tissue, apoptotic index of the cerebral cortex, the expressions of Bax, NLRP3, and caspase-1 p20 in the brain tissue and the levels of IL-1β and IL-18, significant increases in the expression of Bcl-2. However, there was no significant difference in ASC expression. Compared with the T+H group, the content of EB in the cerebral cortex, water content in brain tissue, and apoptotic index, and the expressions of Bax, NLRP3 and caspase-1 p20 were further down-regulated in T+H+M group, the expression of Bcl-2 was further up-regulated, the levels of IL-1β and IL-18 were further decreased [the content of EB (μg/g): 40.49±3.15 vs. 51.96±4.69, water content in brain tissue: (76.58±1.04)% vs. (78.76±1.16)%, apoptotic index: (32.22±3.44)% vs. (38.54±3.89)%, Bax/β-actin: 1.92±0.16 vs. 2.56±0.21, NLRP3/β-actin: 1.94±0.14 vs. 2.37±0.24, caspase-1 p20/β-actin: 1.97±0.17 vs. 2.31±0.19, Bcl-2/β-actin: 0.82±0.07 vs. 0.52±0.04, IL-1β (ng/g): 86.23±7.09 vs. 110.44±10.48, IL-18 (ng/g): 40.18±3.22 vs. 46.23±4.02, all P < 0.05], but there were no statistical significance in all the indicators between T+M group and T+H group. CONCLUSIONS The mechanism by which hydrogen gas alleviates TBI may be related to inhibiting NLRP3 inflammasomes in the cerebral cortex of rats.
Male ; Animals ; Rats ; Rats, Sprague-Dawley ; Actins ; Interleukin-18 ; Inflammasomes ; NLR Family, Pyrin Domain-Containing 3 Protein ; bcl-2-Associated X Protein ; Brain Injuries, Traumatic ; Cerebral Cortex ; Caspases

Objective:To evaluate the role of sphingosine-1-phospho-1 receptor(S1PR1)in the dorsal root ganglion in remifentanil-induced hyperalgesia in rats with incisional pain.Methods:Forty-eight male Sprague-Dawley rats with successful intrathecal and caudal vein catheterization, weighing 260-280 g, aged 2-3 months, were divided into 6 groups ( n= 8 each) using a random number table method: control group (group C), S1PR1 antagonist (FTY720) group (group F), remifentanil group (group R), remifentanil + S1PR1 antagonist (FTY720) group (group R+ F), remifentanil + incisional pain group (group R+ I), and remifentanil + incisional pain + S1PR1 antagonist (FTY720) group (group R+ I+ F). In C group, normal saline 0.1 μg·kg -1·min -1 was intravenously infused for 60 min. In R group, remifentanil 1.0 μg· kg -1·min -1 was infused for 60 min through the caudal vein. In F group, FTY720 3 nmol was intrathecally injected, and 10 min later normal saline 1.0 μg· kg -1·min -1 was infused for 60 min via the caudal vein. In R+ F group, FTY720 3 nmol was intrathecally injected, and 10 min later remifentanil 1.0 μg· kg -1·min -1 was infused for 60 min through the caudal vein. In R+ I group, remifentanil 1.0 μg·kg -1·min -1 was infused for 60 min through the caudal vein while the model of incisional pain was developed. In R+ I+ F group, FTY720 3 nmol was intrathecally injected, 10 min later the incisional pain model was prepared, and remifentanil 1.0 μg·kg -1·min -1 was injected for 60 min through the caudal vein at the same time. The mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured at 24 h before remifentanil or normal saline infusion (T 0) and 2, 6, 24 and 48 h after stopping remifentanil or normal saline infusion (T 1-4). Rats were sacrificed after the last measurement of pain threshold, and the L 4-6 segments of dorsal root ganglion were taken for determination of the expression of S1PR1, NOD-like receptor thermal protein domain-associated protein 3 (NLRP3), interleukin-1β (IL-1β) and glutamate transporter-1 (GLT-1) protein and mRNA (by Western blot and quantitative polymerase chain reaction). Results:Compared with C group, the MWT was significantly decreased and TWL was shortened at T 1-4, the expression of S1PR1, NLRP3 and IL-1β protein and mRNA in dorsal root ganglion was up-regulated, and the expression of GLT-1 protein and mRNA in dorsal root ganglion was down-regulated in R group ( P<0.05), and no significant change was found in the parameters mentioned above in group F ( P>0.05). Compared with R group, MWT was significantly decreased and TWL was shortened at T 1-4, the expression of S1PR1, NLRP3 and IL-1β protein and mRNA in dorsal root ganglion was up-regulated, and GLT-1 protein and mRNA expression in dorsal root ganglion was down-regulated in R+ I group, and MWT was significantly increased and TWL was prolonged at T 1-4, the expression of S1PR1, NLRP3 and IL-1β protein and mRNA in the dorsal root ganglion was down-regulated, and GLT-1 protein and mRNA expression in the dorsal root ganglion was up-regulated in R+ F group ( P<0.05). Compared with R+ I group, MWT was significantly increased and TWL was prolonged at T 1-4, the expression of S1PR1, NLRP3 and IL-1β protein and mRNA in the dorsal root ganglion was down-regulated, and the expression of GLT-1 protein and mRNA in the dorsal root ganglion was up-regulated in R+ I+ F group( P<0.05). Conclusions:The mechanism by which remifentanil induces hyperalgesia is associated with up-regulation of S1PR1 expression, activation of inflammatory factors, and down-regulation of GLT-1 expression in the rats with incisional pain.

Objective:To evaluate the effect of sleep fragmentation on postoperative cognitive dysfunction (POCD) and hippocampal glutaminergic metabolism in aged mice anesthetized with isoflurane.Methods:Forty healthy SPF-grade male C57BL/6J mice, aged 18 months, weighing 20-30 g, were divided into 4 groups ( n= 10 each) by the random number table method: normal control group (group C), sleep fragmentation group (group SF), isoflurane anesthesia/surgery group (group I/S), and sleep fragmentation plus isoflurane anesthesia/surgery group (group SF+ I/S). Group C did not received any treatment. Group SF received sleep fragmentation for 24 h. The right carotid artery exposure was performed under isoflurane anesthesia in group I/S. Group SF+ I/S received isoflurane anesthesia/right carotid artery exposure at 24 h after sleep fragmentation. The metabolic levels of glutamate (Glu), glutamine (Gln), Glu/Gln complex (Glx), and N-acetylaspartate (NAA) and their ratio to creatine (Cr) were measured by in vivo 9.4T hydrogen proton magnetic resonance spectroscopy at 2 h after anaesthesia. Y maze and Morris water maze tests were used to evaluate the cognitive function at 1-7 days after surgery. The mice were sacrificed after the behavioral testing, brain tissues were immediately obtained, and the number of Nissl bodies and density of dendritic spines in the hippocampal CA1 region were measured by Nissl staining and Golgi staining, respectively. Results:Compared with group C, the percentage of exploration time and shuttle times at the novel arm were significantly decreased, the number of crossing the original platform was decreased, the time of stay at the target quadrant was shortened, the ratios of Glu/Cr, Gln/Cr and Glx/Cr in the hippocampal CA1 region were increased, and the ratio of NAA/Cr was decreased, and the number of Nissl bodies and density of dendritic spines were decreased in SF, I/S and SF+ I/S groups ( P<0.05). Compared with group SF and group I/S, the percentage of exploration time and shuttle times at the novel arm were significantly decreased, the number of crossing the original platform was decreased, the time of stay at the target quadrant was shortened, the ratios of Glu/Cr and Glx/Cr in hippocampal CA1 region was increased, the ratio of NAA/Cr was decreased, and the number of Nissl bodies and density of dendritic spines were decreased in group SF+ I/S ( P<0.05). Conclusions:Sleep fragmentation exacerbates POCD in aged mice anesthetized with isoflurane, and the mechanism is related to nerve injury induced by abnormality in hippocampal glutaminergic metabolism excitability.