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Objective:To evaluate the effect of long-term intake of ω-3 polyunsaturated fatty acids (ω-3 PUFAs) on the activation of hippocampal microglia in a mouse model of postoperative cognitive dysfunction (POCD).Methods:Ninety-six clean-grade healthy male C57BL/6 mice, aged 8 weeks, weighing 18-24 g, were stratified according to body weight and divided into 4 groups ( n=24 each) by a random number table method: control diet group (group C), ω-3 PUFAs group (group ω), control diet plus POCD group (group C+ P) and ω-3 PUFAs plus POCD group (group ω+ P). Mice were fed a special ω-3 PUFAs diet (DHA 0.14 g/100 g, EPA 0.03 g/100 g) for 12 weeks in group ω and group ω+ P, while mice were fed with a control diet for 12 weeks in group C and group C+ P.Tibial fracture procedures were performed under isoflurane anesthesia to develop the POCD model after 12 weeks of feeding.The fear conditioning test and Y maze test were performed on 1st and 3rd days after developing the model.The mice were sacrificed after behavioral tests, and the hippocampal tissues were removed for determination of the contents of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) (by gas chromatography-mass spectroscopy), density of Iba-1 positive microglia (by immunofluorescence staining), and expression of mature brain-derived neurotrophic factor (mBDNF) and precursor brain-derived neurotrophic factor (pro-BDNF) (by Western blot), and contents of interleukin-1beta (IL-1β) and interleukin-6 (IL-6) (by enzyme-linked immunosorbent assay). Results:Compared with group C, the contents of DHA and EPA were significantly increased, the percentage of freezing time in the contextual test was increased, mBDNF/pro-BDNF ratio was increased ( P<0.05), no significant change was found in the rotation accuracy in Y maze test, density of Iba-1 positive microglia and contents of IL-1β and IL-6 in hippocampus ( P>0.05) in group ω ( P<0.05), and no significant change was found in the contents of DHA and EPA ( P>0.05), the percentage of freezing time in the contextual test and accuracy of rotation in Y maze test were decreased on 1st and 3rd days after operation, the density of Iba-1 positive microglia and contents of IL-1β and IL-6 were increased, and mBDNF/pro-BDNF ratio was decreased in group C+ P ( P<0.05). Compared with group C+ P, the contents of DHA and EPA were significantly increased, the percentage of freezing time in the contextual test and accuracy of rotation in Y maze test were increased on 1st and 3rd days after operation, the density of Iba-1 positive microglia and contents of IL-1β and IL-6 were decreased, and mBDNF/pro-BDNF ratio was increased in group ω+ P ( P<0.05). Conclusions:Long-term intake of ω-3 PUFAs can improve cognitive function in a mouse model of POCD, and the mechanism may be related to inhibition of activation of hippocampal microglia, reduction of inflammatory responses, and thus increasing the mBDNF/Pro-BDNF ratio.
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Objective To evaluate the effects of GLYX-13 on cognitive function after long-time isoflurane anesthesia in mice. Methods A total of 192 healthy male C57∕B6J mice, aged 8 weeks, weig-hing 22-25 g, were divided into 4 groups(n=48 each)using a random number table: control group (group C), isoflurane anesthesia group(group I), GLYX-13 group(group G), and isoflurane anesthesia plus GLYX-13 group(group IG). The animals were exposed to 15% isoflurane for 6 h in I and IG groups. GLYX-13 1 mg∕kg was injected via the caudal vein at 2 h before anesthesia in G and IG groups. Novel ob-ject recognition test and contextual fear conditioning test were performed on 1st, 3rd and 7th days after an-esthesia. The expression of 2B subunits-containing NMDA receptor(NR2B)and cyclic adenosine mono-phosphate response element-binding protein(CREB)mRNA in the hippocampus was detected by quantita-tive real-time polymerase chain reaction after the end of behavioral tests on 1st, 3rd and 7th days after anes-thesia. Results Compared with group C, the percentage of time spent in exploring a novel object, dis-crimination index and percentage of freezing time were significantly decreased, and the expression of NR2B and CREB mRNA in the hippocampus was down-regulated in group I(P <005). Compared with group I, the percentage of time spent in exploring a novel object, discrimination index and percentage of freezing time were significantly increased, and the expression of NR2B and CREB mRNA in the hippocampus was up-regulated in group IG(P <005). Conclusion GLYX-13 can significantly improve the cognitive func-tion after long-time isoflurane anesthesia in mice.
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Objective To investigate the relationship between spinal neuronal microRNA 212 (miR-212) and phosphorylation of cAMP response element-binding protein (CREB) in a mouse model of bone cancer pain (BCP).Methods Thirty-two male SPF C3H/HeJ mice, aged 4-6 weeks, weighing 20-25 g, were randomly divided into 4 groups (n=8 each) using a random number table: sham operation group (group S), BCP group, BCP + intrathecal negative control locked nucleic acid (LNA) group (group BC) , and BCP + intrathecal miR-212 antisense LNA group (group BL).After the mice were anesthetized with intraperitoneal pentobarbital sodium, 20 μl of α minimal essential medium containing NCTC 2472 cells 2×105 was injected directly into the medullary cavity of the distal femur.In BC and BL groups, negative control LNA and miR-212 antisense LNA 12 pmol/5 μl were intrathecally injected, respectively, once a day for 7 consecutive days, starting from day 14 after inoculation.In S and BCP groups, the equal volume of DNAse/RNAse-free water was given instead.The number of spontaneous flinches (NSF) and mechanical paw withdrawal threshold (MWT) were measured on 1 day before inoculation and 4, 7, 10, 14 and 21 days after inoculation.The mice of each group were sacrificed after measurement of pain threshold on 21 days after inoculation, and the lumbar enlargement segments of the spinal cord were harvested to detect the expression of phosphorylated CREB (p-CREB) and CREB using Western blot.Results Compared with group S, the MWT was significantly decreased, and the NSF was increased on 7-21 days after inoculation, and the expression of p-CREB was up-regulated in BCP, BC and BL groups.Compared with group BCP, the MWT was significantly increased, and the NSF was decreased on 21 days after inoculation, and the expression of p-CREB was down-regulated in group BL, and no significant change was found in the parameters mentioned above in BC group.There was no significant difference in the expression of CREB between the four groups.Conclusion Spinal neuronal miR-212 is involved in the maintenance of BCP probably by promoting phosphorylation of CREB in mice.
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Objective To investigate the changes in the expression of hepatic circadian clock gene in different types of circadian rhythm and the effect of isoflurane anesthesia on the expression of hepatic circadian clwk gene in mice.Methods Seventy-two male C57/B6 mice,aged 2 months,weighing 20-25 g,were randomly divided into 3 groups (n =24 each):normal light/dark (LD) cycle group,reversal LD cycle group and anesthesia group.Normal LD cycle group and anesthesia groupwere maintained in a regular 12 h LD cycle with lights on at 8:00 am and off at 8:00 pm for 3 weeks,and in addition anesthesia was then performed with isoflurane in anesthesia group.Reversal LD cycle group was kept in an inverted12 h LD cycle with lights on at 8:00 pm and off at 8:00 am for 3 weeks.The natural time was converted to circadian time (CT) and the initial time was set at CT0.Isoflurane anesthesia group was exposed to 2％ isoflurane for 6 h during the wakening period from CT14 to CT20.The liver and suprachiasmatic nucleus (SCN) were removed from mice at CT2,CT8,CT14 and CT20 for determination of Clock and Cry1 mRNA expression by real-time quantitative PCR.Results Clock and Cry1 mRNA expression in the liver and SCN showed rhythm in the two different types of circadian rhythm.Compared with that in SCN,the peak phase of Clock and Cry1 mRNA expression in livers was delayed in two different types of circadian rhythm.Isoflurane anesthesia caused a peak phase delay of Cry1 and Clock mRNA expression in livers as compared with normal LD cycle group.Conclusion Circadian clock gene in livers shows rhythmic expression in different types of circadian rhythm,and isoflurane anesthesia can cause a large peak phase delay of circadian clock gene expression in livers of mice.
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Objective To investigate spatial memory ability of intraperitoneal injection of resveratrol in a mice model of chronic constriction injury of sciatic nerve(CCI).Methods Forty-four C57BL/6 mice were divided randomly into 4 groups:sham group (n=14),CCI group (n=14),resveratrol pre-treatment group (i.p.resveratrol 100 mg/kg 30 minutes before CCI model,n=8) and resveratrol post-treatment group (i.p.resveratrol 100 mg/kg 14 days after CCI model,n =8).CCI group,resveratrol pre-treatment group and resveratrol post-treatment group were operated with the model of neuropathic pain induced by chronic constriction injury of sciatic nerve.In shamoperated controls,an identical surgical procedure was performed,except that the sciatic nerve was not ligated.This was accomplished by using intellicage for mice by newbehavior to record their spatial memory after surgery.Results (l) Resveratrol pre-treatment group showed improved spatial memory ability compared with sham group and CCI group during day 17-21 (17 d:(55.80±7.66) ％,(51.20±7.94) ％ ; 18 d:(60.20±3.89) ％,(49.80±8.61) ％ ; 19 d:(62.20±7.25) ％,(51.20±6.83) ％ ;20 d:(63.00±9.69) ％,(48.40±8.84) ％ ;21 d:(56.80±7.52) ％,(47.20±4.54) ％)(P＜0.05),compared with CCI group.(2)From day 26,the spatial memory damage was observed in mice with CCI (26 d:(37.50±5.50)％,(51.80±9.01)％;27 d:(37.25±4.19)％,(51.20±5.76)％;28 d:(42.25± 3.50) ％,(52.80± 7.52) ％) (P＜ 0.05),compared with sham group.And this damage could be reversed by resveratrol,which was injected when the chronic pain was stable (26 d (46.60± 5.27) ％,27 d (54.00± 7.31) ％,28 d (52.60±4.39)％),compared with CCI group(P＜0.05).Conclusion Chronic constriction injury of sciatic nerve mice due to spatial memory impairment can be improved by resveratrol.