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Objective@#To evaluate the relationship between p38 mitogen-activated protein kinase (p38MAPK) and G protein-coupled receptor kinase 2 (GRK2) in the development of persistent postoperative pain in rats.@*Methods@#Pathogen-free healthy male Sprague-Dawley rats, weighing 200-250 g, aged 2 months, were used in this study.Sixty rats in which intrathecal catheters were successfully implanted were divided into 6 groups (n=10 each) using a random number table method: sham operation group (group S), sham operation plus dimethyl sulfoxide (DMSO) group (group D), sham operation plus GRK2 degradation inhibitor MDL28170 group (group M), persistent postoperative pain group (group PPP), persistent postoperative pain plus DMSO group (group PPP+ D) and persistent postoperative pain plus MDL28170 group (group PPP+ M). Persistent postoperative pain was evoked by skin/muscle incision and retraction (SMIR). Immediately after operation and at 1, 2 and 3 days after operation, normal saline 20 μl was intrathecally injected once a day in S and PPP groups, 5% DMSO 10 μl was intrathecally injected once a day in D and PPP+ D groups, and MDL28170 10 μl (50 μg) was intrathecally injected once a day in M and PPP+ M groups.The mechanical paw withdrawal threshold (MWT) was measured at 1 day before operation and 3, 7, 14 and 21 days after operation (T1-4). Four rats in each group were selected after behavioral testing at T3 and sacrificed, and the L4-6 segments of the spinal cord were removed for determination of the expression of phosphorylated p38MAPK (p-p38MAPK) by Western blot.@*Results@#There was no significant difference in MWT at each time point or expression of p-p38MAPK among group S, group D and group M (P>0.05). Compared with group S, the MWT was significantly decreased, and the expression of p-p38MAPK was up-regulated in PPP, PPP+ D and PPP+ M groups (P<0.05). Compared with group PPP, the MWT was significantly increased, and the expression of p-p38MAPK was down-regulated in group PPP+ M (P<0.05), and no significant change was found in the MWT or expression of p-p38MAPK in group PPP+ D (P>0.05).@*Conclusion@#Down-regulated expression of spinal GRK2 can promote the activation of p38MAPK in the spinal cord and is involved in the development of persistent postoperative pain in rats.
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Objective To evaluate the relationship between p38 mitogen-activated protein kinase (p38MAPK) and G protein-coupled receptor kinase 2 (GRK2) in the development of persistent postoperative pain in rats.Methods Pathogen-free healthy male Sprague-Dawley rats,weighing 200-250 g,aged 2 months,were used in this study.Sixty rats in which intrathecal catheters were successfully implanted were divided into 6 groups (n =10 each) using a random number table method:sham operation group (group S),sham operation plus dimethyl sulfoxide (DMSO) group (group D),sham operation plus GRK2 degradation inhibitor MDL28170 group (group M),persistent postoperative pain group (group PPP),persistent postoperative pain plus DMSO group (group PPP+D) and persistent postoperative pain plus MDL28170 group (group PPP+M).Persistent postoperative pain was evoked by skin/muscle incision and retraction (SMIR).Immediately after operation and at 1,2 and 3 days after operation,normal saline 20 μl was intrathecally injected once a day in S and PPP groups,5％ DMSO 10 μl was intrathecally injected once a day in D and PPP+D groups,and MDL28170 10 μl (50 μg) was intrathecally injected once a day in M and PPP+M groups.The mechanical paw withdrawal threshold (MWT) was measured at 1 day before operation and 3,7,14 and 21 days after operation (T1-4).Four rats in each group were selected after behavioral testing at T3 and sacrificed,and the L4-6 segments of the spinal cord were removed for determination of the expression of phosphorylated p38MAPK (p-p38MAPK) by Western blot.Results There was no significant difference in MWT at each time point or expression of p-p38MAPK among group S,group D and group M (P＞0.05).Compared with group S,the MWT was significantly decreased,and the expression of p-p38MAPK was up-regulated in PPP,PPP+D and PPP +M groups (P＜ 0.05).Compared with group PPP,the MWT was significantly increased,and the expression of p-p38MAPK was down-regulated in group PPP+M (P＜0.05),and no significant change was found in the MWT or expression of p-p38MAPK in group PPP+D (P＞0.05).Conclusion Down-regulated expression of spinal GRK2 can promote the activation of p38MAPK in the spinal cord and is involved in the development of persistent postoperative pain in rats.
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Objective To evaluate the role of spinal histone acetylation in persistent postoperative pain in rats. Methods Pathogen?free healthy male Sprague?Dawley rats, weighing 200-250 g, aged 2 months, in which intrathecal catheters were implanted at the lumbar level according to an improved method, were used in the study. Eighty?four rats, in which intrathecal catheters were successfully implanted, were divided intoⅠ-Ⅵgroups(n=14 each)using a random number table. Artificial cerebrospinal fluid 20 μl was intrathecally administered at 1, 2, 3 and 4 days before operation and 1 day after operation inⅠandⅣgroups. At 1, 2, 3 and 4 days before operation and 1 day after operation, dimethyl sulfoxide 10 μl and SAHA(50 μg∕10μl)were intrathecally injected inⅡandⅤgroups and inⅢandⅥgroups, respective?ly, followed by artificial cerebrospinal fluid(10 μl)flush after each injection. Rats underwent sham oper?ation inⅠ?Ⅲ groups. Persistent postoperative pain was evoked by skin∕muscle incision and traction in Ⅳ?Ⅵ groups. The mechanical paw withdrawal threshold(MWT)was measured at 1 day before operation(T0)and 1, 3, 7, 14 and 21 days after operation(T1?5). Four rats were sacrificed in each group after measurement of MWT at T4, and the lumbar segments(L4?6)of the spinal cord were removed for determi?nation of the expression of acetylated histone H3(Ac?H3)and Ac?H4 by Western blot. Results There was no significant difference in each index amongⅠ?Ⅲ groups(P>0.05). Compared with group Ⅰ, the MWT was significantly decreased at T2?5, and the expression of Ac?H3 and Ac?H4 was down?regulated at T4 in group Ⅳ(P<0.05). Compared with group Ⅳ, the MWT was significantly increased at T2?5, and the expression of Ac?H3 and Ac?H4 was up?regulated at T4in group Ⅵ(P<0.05). Conclusion Histone acetylation is involved in the development and maintenance of persistent postoperative pain in rats.
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Objective To investigate the change of spinal G protein-coupled receptor kinase 2 (GRK2) expression in persistent postoperative pain evoked by skin/muscle incision and retraction (SMIR) in rats.Methods 40 male Sprague Dawley (SD) rats were divided into 2 groups (n =20) using a random number table:sham operation group and skin/muscle incision and retraction group (SMIR group).A rat model of peristent postoperativepain evoked by SMIR was made according to the method described by Flatters.Pain behavior was assessed by paw mechanical withdrawal threshold (MWT) to yon Frey filament stimulationintensity at 1 d before operation (T0) and 3 d (T1),7 d (T2),14 d (T3) and 21 d (T4) after operation.4 rats in each group were sacrificed at T0-4,the L4-L6 segments of the spinal cord were obtained for determination of GRK2 expression in the spinal cord by Western blot.Results Compared with T0,the MWT was significantly decreased and the expression of spinal GRK2 was down-regulated at T1-T4 in SMIR group (P ＜ 0.05).Compared with sham operation group,the MWT and the expression of spinal GRK2 was decreased at T1-T4 in SMIR group (P ＜ 0.05).Conclusions The down-regulation of expression of spinal GRK2 may be involved in the development and maintenance of persistent postoperative pain in rats evoked by SMIR.
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Objective To investigate the changes in acetylation of histone in the spinal dorsal horn in a rat model of persistent postoperative pain.Methods Ninety-six malc Sprague-Dawley rats,weighing 200-250 g,aged 6-8 weeks,were randomly divided into 2 groups (n=48 each) using a random number table:sham operation group (group S) and persistent postoperative pain group (group PPP).The rat model of persistent postoperative pain evoked by skin/muscle incision and retraction was established according to the method described by Flatters.After the rats were anesthetized with intraperitoneal chloral hydrate,the skin and superficial muscle of the medial thigh were incised and retractors inserted.This tissue was retracted for 1 h.The mechanical paw withdrawal threshold (MWT) was measured at 1 day before operation and 1,3,7,14,and 21 days after operation.Four animals were sacrificed in each group after measurement of MWT at each time point for detection of acetylated histone H3 (Ac-H3) and acetylated histone H4 (Ac-H4) expression (by Western blot analysis) and the number of Ac-H3 and Ac-H4 positive cells in the spinal cord horn (by immunofluorescence histochemistry).Results Compared with group S,the MWT was significantly decreased at 3,7,14 and 21 days after operation,the expression of Ac-H3 and Ac-H4b was significantly down-regulated at 3,7 and 14 days after operation,and the number of Ac-H3 and Ac-H4 positive cells was significantly decreased at 7,14 and 21 days after operation in group PPP (P＜0.05 or 0.01).The MWT,expression of Ac-H3 and Ac-H4b,and the number of Ac-H3 and Ac-H4 positive cells were significantly higher at 21 days after operation than at 14 days after operation in group PPP (P＜0.05).Conclusion Acetylation of histone in the spinal dorsal horn is decreased after operation,which may be involved in the development and maintenance of persistent postoperative pain in rats.
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Objective To evaluate the role of p38 mitogen-activated protein kinase (p38MAPK) in the spinal cord in the development of persistent postoperative pain evoked by skin/muscle incision and retraction (SMIR) and the relationship with Toll-like receptor 4 (TLR4).Methods One hundred and twenty male SpragueDawley rats,weighing 200-250 g,aged 2 months,in which intrathecal catheters were successfully implanted,were randomly divided into 5 groups (n =24 each) using a random number table:sham operation group (group S),SMIR group,SMIR + dimethyl sulfoxide (DMSO) group (group DMSO),SMIR + p38MAPK inhibitor SB203580 group (group SB203580) and SMIR + TLR4 small interference RNA (siRNA) group (group TLR4siRNA).The rats were anesthetized with intraperitoneal chloral hydrate 400 mg/kg.The skin and superficial muscle of the medial thigh were incised and a small pair of retractors inserted.This tissue was retracted for 1 h causing potential stretch of the saphenous nerve.2％ DMSO 10 μl and SB203580 5 μg were injected intrathecally at 30 min before operation and 1-12 days after operation in DMSO and SB203580 groups,respectively.TLR4siRNA 2 μg was administered intrathecally at 1 day before operation and 1-12 days after operation once a day in group TLR4siRNA.Mechanical paw withdrawal threshold to von Frey filament stimulation (MWT) was measured at 1 day before operation and 1,3,7,12 and 22 days after operation.Four rats in each group were sacrificed after measurement of MWT at each time point,and the L4-6 segments of the spinal cord were obtained for detection of the expression of phosphorylated p38MAPK (p-p38MAPK) by Western blot analysis.Results Compared with group S,MWT was significantly decreased after operation,and the expression of p-p38MAPK was up-regulated after operation in SMIR and DMSO groups.Compared with group SMIR,MWT was significantly increased after operation,and the expression of p-p38MAPK was down-regulated after operation in SB203580 and TLR4siRNA groups,and no significant changes in MWT and p-p38MAPK expression were found at each time point in group DMSO.Conclusion TLR4-triggered activation of p38MAPK in spinal cord is involved in the development of SMIR-evoked persistent postoperative pain in rats.
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Objective To investigate the role of Toll-like receptor4 (TLR4) activation in spinal cord in a rat model of persistent postoperative pain evoked by skin/muscle incision and retraction(SMIR).Methods Ninetysix male SD rats weighing 200-250 g were randomly divided into 4 groups(n =24 each):group sham operation; group SMIR; group SMIR + IT scramble siRNA and group SMIR + IT TLR4siRNA.The rat model of persistent postoperative pain evoked by SMIR was established according to the method described by Flatters.The TLR4 siRNA were administered intrathecally for 7 days starting from 1 day beforc surgcry.Pain behavior was assessed by paw mechanical withdraw threshold (MWT) to Electronic von Frey Anesthesiometer stimulation at 1 day before and 1,3,7,12,and 22 days after operation.Four animals were sacrificed at each time point in each group for detection of the expression of TLR4 protein in the spinal cord by Western blot analysis.Results Compared to group sham group,MWT was significantly descreased at 3,7,12,and 22 days after operation,while the expression of TLR4 protein in the spinal cord were significantly increased at 3,7,12 days after operation in group SMIR and group SMIR + IT scramble siRNA ; IT TLR4siRNA significantly attenuated the hyperalgesia induced by SMIR and descreased the expression of TLR4 protein at 3,7,12 days after operation in group SMIR + IT TLR4siRNA.Conclusion TLR4 activation in spinal cord plays an important role in the development of SMIR-evoked persistent postoperative pain in rats.
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Objective To investigate the role of microglial activation in spinal cord in a rat model of persistent postoperative pain evoked by skin/muscle incision and retraction (SMIR) .Methods Seventy-two male SD rats weighing 200-250 g in which intrathecal (IT) catheter was successfully inserted were randomly divided into 3 groups ( n = 24 each) : group sham operation; group SMIR and group SMIR + FT minocycline (a specific microglia inhibitor) . The rat model of persistent postoperative pain evoked by SMIR was established according to the method described by Flatters. Pain behavior was assessed by paw mechanical withdrawal threshold ( MWT) to von Frey filament stimulation at 1 day before (T0,baseline) and 3, 7, 12, 22 and 32 days after operation (T1-5,) . Four animals were sacrificed at each time point in each group for detection of the expression of Iba-1 (a specific marker of microglia) in the spinal dorsal horn by immunofluorescence and the microglia was counted. Results MWT was significantly decreasedat T1-4, while the expression of Iba-1 and microglia counts in the spinal dorsal horn were significantly increased at T1, 2 by SMIR in group Ⅱ. IT minocycline significantly attenuated the hyperalgesia induced by SMIR at T1-4 and decreased Iba-1 expression and microglia counts at T1,2 in group Ⅲ. Conclusion Microglial activation in the spinal cord plays an important role in the development and maintenance of SMIR-evoked persistent postoperative pain in rats.
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ObjectiveTo investigate the role of NF-κB signaling pathway in the spinal cord in persistent postoperative pain evoked by skin/muscle incision and retraction (SMIR) in rats.MethodsNinety male SD rats weighing 200-250 g in which intrathecal (IT) catheter was successfully implanted without complication were randomly divided into 3 groups ( n =30 each):group sham operation ( group S ) ; groups SMIR and group pyrrolidine dithiocarbarnate (a NF-κB inhibitor) (group PDTC).Persistent postoperative pain was evoked by SMIR according to the method described by Flatters in groups SMIR and PDTC.PDTC 10 ng in 10 μl was injected IT over 30 s once a day for 7 consecutive days after operation in group PDTC.Mechanical paw withdrawal threshold to von Frey filament stimulation (MWT) was measured at 1 d before (T0,baseline) and 1,3,7,12 and 22 d after surgery (T1-5).Five animals in each group were sacrificed at each time point after MWT measurement and their lumbar segments of the spinal cord were removed for determination of TNF-α content (by ELISA).ResultsSMIR significantly decreased MWT after operation at T1-5 and increased TNF-α content in the spinal cord at T3-5.PDTC significantly attenuated SMIR-induced hyperalgesia and increase in TNF-α content in the spinal cord.Conclusion NF-κB signaling pathway in the spinal cord plays an important role in the development of SMIR-induced persistent postoperafive pain in rats.
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Objective To investigate the glial activation in the spinal cord in a rat model of persistent postoperative pain. Methods Forty-eight adult male SD rats weighing 200-250 g were randomly divided into 2 groups ( n = 24 each): group Ⅰ sham operation (group S) and group Ⅱ persistent postoperative pain. Persistent postoperative pain was evoked by skin/muscle incision and retraction (SMIR) as described by Flatters. Pawwithdrawal threshold to yon Frey hair stimulation was measured before operation (baseline) and at 1, 3, 12, 22and 32 d after establishment of the model. Four animals were sacrificed at each time point and lumbar segment of the spinal cord was removed for determination of expression of glial fibrillary acidic protein (GFAP) in the astrocytes by immunofluorescence histo-chemistry assay. Results The mechanical threshold started to decrease at 1 d after establishment of the model, and peaked at 12 d after establishment of the mode. Immunofluorescence histochemistry assay demonstrated that GFAP expression in the dorsal horn was significantly increased at 3 d after estabhshment of the model and reached the peak at 12 d and was maintained at the high level until 22 d after establishment of the model. Conclusion Glial activation is involved in the mechanism of persistent postoperative pain evoked by SMIR.
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Objective To investigate the effects of intrathecal (IT) gabapentin on the analgesic efficacy of morphine in a rat model of incisional pain. Methods Forty-eight male SD rats in which IT catheters were successly inserted according to the method described by Yaksh were randomly divided into 6 groups ( n = 8 each): Ⅰ sham operation group, Ⅱ incisional pain group, Ⅲ GBP 50 μg group, Ⅳ morphine 2.5 μg group, Ⅴ morphine 5 μg group, and Ⅵ morphine 2.5 μg + gabapentin 50 μg group. In group Ⅰ , IT artificial cerebrospinal fluid (ACSF)10 μl was injected and then 1.4% isoflurane was inhaled for 5 min. IT ACSF 10 μl, gabapentin 50μg and morphine 2.5 and 5 μg were injected 30 min before the establishement of the model in group Ⅱ -Ⅴ respectively. Paw withdrawl threshold (PWT) to mechanical stimulation and paw withdrawal latency (PWL) to a thermal nociceptive stimulus were measured at 2 h after the establishement of the model. Results Compared with group Ⅰ , MWT was significantly decreased and TWL was significantly shortened in group Ⅱ , Ⅲ and Ⅳ ( P ＜ 0.05), but no significant change in MWT and TWL was found in group Ⅴ and Ⅵ (P＞0.05). Compared with group Ⅱ , MWT was significantly increased and TWL was significantly prolonged in group Ⅴ and Ⅵ (P ＜ 0.05), but no significant change in MWT and TWL was found in group Ⅲ and Ⅳ/ ( P ＞ 0.05). MWT was significantly decreased and TWL was significantly shortened in group Ⅲ and Ⅳ compared with group Ⅵ ( P ＜ 0.05). Conclusion IT gabapentin enhances the analgesic efficacy of morphine in a rat model of incisional pain.
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Objective To investigate the effects of intrathecal (IT) neostigmine on the excitatory amino-acid content in the L4-5 segment of spinal cord in a rat model of incisional pain. Methods Thirty-two male SD rats weighing 250-270 g were anesthetized with intraperitoneal pentobarbital 40 mg ? kg-1 . Intrathecal catheter was placed with the tip reaching the lumbar region according to the method of Yaksh. Five days later an 1 cm long incision was made in the plantar region of the right hind paw under isoflurane anesthesia according to the method of Brennan. Pain behavior was assessed at 1h after incision by cumulative pain score. The animals were randomly divided into four groups with 8 animals in each group: Ⅰsham operation group received IT artificial cerebro-spinal fluid (ACSF) 20 ?l but no incision was made in the hind paw; Ⅱ control group received ACSF 20 ?1 30 min before incision was made; Ⅲ postoperative neostigmine group received IT neostigmine 10 ?g 30 min after incision; Ⅳ preoperative neostigmine group received IT neostigmine 10 ?g before incision. 2h after incision the animals were decapitated and lumbar segment of spinal cord was removed for determination of aspartate and glutamate contents by high performance liquid chromatography (HPLC) with fluorescence detection. Results The cumulative pain scores in group Ⅱ were significantly higher than those in group Ⅰ (P 0.05) . Conclusion The decline in the increased excitatory amino-acid contents in spinal cord induced by incisional pain is involved in the mechanisms of analgesia provided by IT neostigmine.
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Objective Substance P and its receptor are thought to play an important role in the mechanisms of pain The purpose of this study was to investigate the effects of intrathecal (IT) morphine on substance P expression in the dorsal horn of spinal cord in a rat model of incisional pain Methods Sixteen male SD rats weighing 250 300g were randomly divided into four groups of 4 animal each: in group Ⅰ (sham operation) 30 min after IT normal saline(NS) 20 ?l 1 4% isoflurane was inhaled for 5 min but no incision was made; in group Ⅱ (control group) 30 min before incision NS 20 ?l was given IT; in group Ⅲ (postoperative analgesia group) morphine 5 ?g (10 ?l) was given IT 30 min after incision; group Ⅳ ( preemptive analgesia group) morphine 5 ?g (10 ?l) was given IT 30 min before incision The animals were anesthetized with intraperitoneal pentobarbital sodium 40 mg?kg -1 PE 10 catheter was inserted intrathecally to the lumbar region according to method of Yaksh 5 days later incision of 1 cm long was made in the plantar region of left hindpaw parallel to the muscle under isoflurane anesthesia according to the method of Brennan Pain behavior was assessed by a cumulative pain score Immuno histochemistry technique was used to measure the expression of substance P Results IT morphine given either before or after incision decreased the cumulative pain scores Incision made in the plantar region of left hindpaw increased substance P expression in the ipsilateral dorsal horn of spinal cord (0 62?0 07 vs 0 40?0 09) In group Ⅳ increase in substance P expression in the dorsal horn of spinal cord was inhibited Conclusions The analgesia provided by preemptive IT morphine is possibly mediated via the decrease in substance P in the dorsal horn of spinal cord
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Objective:To investigate effects of propofol on nitric oxide synthase (NOS) activity and nitric oxide (NO)output of rat brain. Method: Sixteen SD rats were divided randomly into two groups. The animals were administered introperitoneally(ip) normal saline 10 ml?kg~(-1)(control group)or propofol 100mg?kg~(-1)(propofolgroup),respectively. These rats were decapitated immediately after having disappeared righting reflex. After rapid removal of cerebellum, brain stem,hippocampus and cerebral cortex,tissues were homogenized and centrifuged. NOS activity and NO output were assayed with spectrophotometric analysis. Result: In propofol group,NOS activity was significantly inhibited, NO outpul was significantly reduced in cerebellum, brain stem,hippoeampus and cerebral cortex as compared with those of control group(P
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Objective To investigate the effects of GABAA receptor agonist-muscimol and GABAA receptor antagonist-bicuculline on brain cyclic adenosine monophosphate (cAMP) content in rats undergoing isoflurane anesthesia. Methods Forty-eight SD rats of both-sexes weighing 200-250g were randomly divided into 6 groups: group I received intraperitoneal (ip) normal saline (NS) 10ml.kg-1 (control group); group II in which animals inhaled 1.4% isoflurane for 30 min, 30 min after NS ip (isoflurane group);group IE in which animals inhaled 1.4% isoflurane for 30 min, 30 min after muscimol Img-kg ip (muscimol + isoflurane group); group IV in which animals inhaled 1.4% isoflurane for 30min, 30 min right after bicuculline 8 mg.kg-1 ip (bicuculline + isoflurane group); group V received muscimol lmg. kg-1 (muscimol group); group VI received bicuculline 8mg.kg (bicuculline group). The animals were decapitated 1h after 30min isoflurane inhalation or intraperitoneal NS or muscimol or 5min after bicuculline ip (rats developed convulsion within 7 min after bicuculline ip) . Brain was removed immediately for determination of cAMP content of cortex or brain stem. Loss of righting reflex was taken as sign of anesthesia. Brain cAMP content was measured by competitive protein binding assay. Results Muscimol shortened the time of loss of righting reflex induced by isoflurane (P
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Objective It has been shown that protein kinase C (PKC), especially PKCy is involved in the nociceptive processing at the spinal level. This study was designed to investigate the effects of intrathecal (IT) morphine on PKCy immuno-reactivity in the spinal dorsal horn in a rat model of incisional pain. Methods Twenty-four male SD rats weighing 250-300 g were anesthetized with intraperitoneal pentobarbital 40 mg?kg-1. PE-10 catheter was inserted intrathecally to the lumbar region according to Yaksh. Five days later an incision of 1cm long was made in the plantar region of left hindpaw, parallel to the muscle under isoflurane anesthesia according to Brennan. The animals were randomly divided into 4 groups with 6 animals in each group : group Ⅰ sham-operation group received IT artificial cerebro-spinal fluid (ACSF) 20 ?l and 30 min later inhaled 1.4% isoflurane for S min but no incision was made; group Ⅱ received ACSF 20 ?l IT 30 min before incision was made; group Ⅲ post-incisional morphine group received morphine 5 ?g IT 30 min after incision and group Ⅳ pre-incisional morphine group received morphine 5 ?g IT 30 min before incision. The animals were sacrificed under general anesthesia 2 h after incision. The L4-5 segment of spinal cord was removed for determination of the expression of PKC? in the spinal dorsal horn by immuno-histochemical method.Results In group Ⅱ the PKC?-IR gray density in the spinal dorsal horn of the operated side was significantly higher than that of contralateral side and that in group Ⅰ( P
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Objective To investigate the effects of intrathecal neostigmine on nitric oxide synthase (NOS) activity, nitric oxide (NO) production and cyclic guanosine 3',5' monophosphate (cGMP) content of the spinal cord in a rat model of incisional pain Methods Male SD rats weighing 250 300g were anesthetized with intraperitoneal pentobarbital sodium 40 mg?kg -1 Intrathecal(IT) catheter was implanted and the tip of the cathter reached the lumbar region, according to the method of Yaksh Incision was made in the plantar aspect of the left hindpaw under 1 4% isoflurane anesthesia, according to the method of Brennan 64 male SD rats were were divided randomly into four groups GroupⅠ received IT 0 9% NaCl 20 ?l and 30 min later inhaled 1 4% isoflurane for 5 min but no incision was made Group Ⅱ received IT 0 9% NaCl 20 ?l 30 min before incision Group Ⅲ received IT neostigmine 10?g(10?l) 30 min after incision GroupⅣreceived IT neostigmine 10?g(10?l) 30 min before incision In group Ⅲ and Ⅳ 0 9%NaCl 10 ?l was flushed through IT catheter after IT neostigmine administration A cumulative pain score was utilized to assess pain behavior The animals were decapitated 2h after incision and the spinal cord was immediately removed and lumbar enlargement of the spinal cord was dissected on ice NOS activity, NO production and cGMP content were measured by spectrophotometry and radioimmunoassy Results Cumulative pain score in group Ⅲ and group Ⅳ was significantly lower than that in groupⅡ(P
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Objective To investigate the effects of isoflurane on cyclic adenosine monophosphate (cAMP ) content of brain in the rats. Methods Fourty SD rats were allocated randomly to 5 groups: no administration(control group,n=8), inhalation of 1.4% isoflurane until losing of righting reflex(loss of righting reflex group,n=8), inhalation of 1.4% isoflurane lasting 30 min(anesthesia group,n=8) ,righting reflex recovery after cessation of 30-min inhalation of 1.4% isoflurane (recoveryⅠ group,n=8) and 30 min after cessation of 30-min inhalation of 1.4% isoflurane (recovery Ⅱ group,n=8). The rats of each group were decapitated at the end of procedures to measure the cAMP content of brain tissue with competitive protein binding assay.Results As compared with that in control group,the cerebrocortical cAMP content only in anesthesia group significantly increased by 49% (P
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Tn investigate the effects of propofol on Ca~(2+) ATPase activity in rat cerebral synaptic membrane. Method: Thirty SD rats were divided randomly into three groups. The aminals were administtered introperi toneally(ip) propofol 50mg?kg~(-1), 100mg?kg~(-1) or normal saline 10mg?kg~(-1)(control group), respectively. These rats were immediately decapitated after having disappeared righting reflex. In oredr to prepare synaptosomes, brain tissues were dissected on ice, then homogenized and centrifuged. Ca~(2+)-ATPase activity was assaed with spcetrophotometric analysis. Result: Propofol 100mg?kg~(-1) ip significantly inhibited Ca~(2+)-ATPase activity of cerebrocortical, brain stems and hippocampal synaptic membrane as compared with that of normal saline group(P
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To investigate the effects of ketamine on nitric oxide synathase(NOS)activity, nitrc oxide (NO) output and cyclic guanosine 3', 5'-monophosphate(cGMP)content in the rat brain. Method: Thirty two SD rats were divided randomly into control group and ketamine group. The aminals were administred intraperitoneally(ip)normal saline 10mg?kg~(-1) or ketamine 100mg?kg~(-1), respectively. NOS activity and NO output were assassed with spectrophotometric analysis, cGMP content was measured with radioimmunoassay, Result: Ketamine 100mg?kg~(-1) ip significantly inhibited NOS activity(P
