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Objective@#To investigate the effects of glutamate (Glu) injected into hypothalamic paraventricular nucleus (PVN) on visceral pain of chronic visceral hypersensitivity (CVH) rats and its possible mechanism.@*Methods@#Newborn SD rats were given CVH rat model by colorectal distension (CRD) on the 8th, 10th and 12th day after birth. Thirty rats with successful CVH model were randomly divided into CVH model group (CVH group), CVH + injection of saline into PVN group (NS group), CVH+ injection of Glu into PVN (3, 6, and 12 μg Glu, namely G3, G6, and G12, respectively), 6 rats in each group, and 6 SD rats with matching body mass were taken as sham operation group (Sham group). The pain behavior of the rats was evaluated by pain threshold, abdominal withdrawal reflex (AWR) score, and abdominal external oblique muscle electromyography (EMG). The expression of arginine vasopressin (AVP) and the proliferation of colon tissue were detected by immunohistochemical staining. The apoptosis of colon tissue was detected by TUNEL.@*Results@#Compared with the NS group, the pain thresholds of the G3, G6 and G12 groups increased, and the AWR scores and EMG amplitudes decreased. The differences were statistically significant(Pain threshold: t=7.65, 16.31, 24.78, both P<0.05; AWR scores: t=-2.98, -4.77, -7.29, both P<0.05; EMG amplitudes: t=-3.06, -5.75, -8.92, both P<0.05). Compared with the Sham group, the expression of AVP in PVN of the CVH group and NS group decreased ((42.63±5.20) %, (18.67±2.94) %, (17.53±2.47) %; t=6.95, t=7.56, both P<0.05). The expression of AVP was increased after different doses of Glu into PVN, and the AVP level in G12 group ((18.15±6.49)%) was higher than that of NS group, the difference was statistically significant (t=-4.21, P<0.05). Compared with the Sham group, the expression of PCNA in colonic mucosal cells of the CVH group and NS group decreased ((65.48±1.68) %, (18.39±1.67) %, (17.69±1.68) %; t=34.35, t=34.80, both P<0.05). The expression of PCNA was increased after different doses of Glu injected into PVN, and the PCNA level in G12 group ((59.91±5.63)%) was higher than that of NS group, the difference was statistically significant (t=-12.44, P<0.05). Compared with the Sham group, the expression of apoptotic cells in colonic mucosal cells of the CVH group and NS group increased ((23.38±11.40)%, (83.79±3.57)%, (80.91±2.47)%; t=-8.77, t=-8.54, both P<0.05). The expression of apoptotic cells was decreased after different doses of Glu into PVN, and the G12 group was ((18.15±6.49) %). Compared with NS group, the difference was statistically significant (t=15.65, P<0.05).@*Conclusion@#Injection of Glu into hypothalamic PVN can alleviate the visceral pain behaviors in CVH rats, and its mechanism may be related to arginine vasopressin.
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Objective To investigate the effects of glutamate (Glu) injected into hypothalamic pa-raventricular nucleus (PVN) on visceral pain of chronic visceral hypersensitivity (CVH) rats and its possi-ble mechanism. Methods Newborn SD rats were given CVH rat model by colorectal distension (CRD) on the 8th,10th and 12th day after birth. Thirty rats with successful CVH model were randomly divided into CVH model group (CVH group),CVH + injection of saline into PVN group (NS group),CVH+ injection of Glu into PVN (3,6,and 12 μg Glu,namely G3,G6,and G12,respectively),6 rats in each group,and 6 SD rats with matching body mass were taken as sham operation group (Sham group). The pain behavior of the rats was evaluated by pain threshold,abdominal withdrawal reflex (AWR) score,and abdominal external ob-lique muscle electromyography (EMG). The expression of arginine vasopressin (AVP) and the proliferation of colon tissue were detected by immunohistochemical staining. The apoptosis of colon tissue was detected by TUNEL. Results Compared with the NS group, the pain thresholds of the G3, G6 and G12 groups in-creased,and the AWR scores and EMG amplitudes decreased. The differences were statistically significant (Pain threshold:t=7. 65,16. 31,24. 78,both P<0. 05;AWR scores:t=-2. 98,-4. 77,-7. 29,both P<0. 05;EMG amplitudes:t=-3. 06,-5. 75,-8. 92,both P<0. 05). Compared with the Sham group,the expression of AVP in PVN of the CVH group and NS group decreased ((42. 63±5. 20) %,(18. 67±2. 94) %,(17. 53± 2. 47) %; t=6. 95,t=7. 56,both P<0. 05). The expression of AVP was increased after different doses of Glu into PVN,and the AVP level in G12 group ((18. 15±6. 49)%) was higher than that of NS group,the difference was statistically significant (t=-4. 21,P<0. 05). Compared with the Sham group,the expression of PCNA in colonic mucosal cells of the CVH group and NS group decreased ((65. 48±1. 68) %,(18. 39± 1. 67) %,(17. 69±1. 68) %;t=34. 35,t=34. 80,both P<0. 05). The expression of PCNA was increased after different doses of Glu injected into PVN,and the PCNA level in G12 group ((59. 91±5. 63)%) was higher than that of NS group,the difference was statistically significant (t=-12. 44,P<0. 05). Compared with the Sham group,the expression of apoptotic cells in colonic mucosal cells of the CVH group and NS group increased ((23. 38±11. 40)%,(83. 79± 3. 57)%,(80. 91± 2. 47)%;t=-8. 77,t=-8. 54,both P<0. 05). The expression of apoptotic cells was decreased after different doses of Glu into PVN,and the G12 group was ((18. 15±6. 49) %). Compared with NS group,the difference was statistically significant ( t=15. 65,P<0. 05). Conclusion Injection of Glu into hypothalamic PVN can alleviate the visceral pain be-haviors in CVH rats,and its mechanism may be related to arginine vasopressin.
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Background:Cerebellar fastigial nucleus (FN)is involved in regulation of visceral activities such as cardiovascular, ingestion,respiratory,and acute gastric mucosal injury,yet it is unclear whether it participates in the regulation of visceral hypersensitivity and what is the possible mechanism. Aims:To investigate the effect and possible mechanism of glutamic acid (Glu ) injection into cerebellar FN on chronic visceral hypersensitivity in rats. Methods: Chronic visceral hypersensitivity rat model was established by neonatal colorectal distension (CRD). After 8 weeks,the rats were divided into CRD group,solvent group (0. 2 μL 0. 9% NaCl solution injection into cerebellar FN),high-,medium-,low-dose Glu groups (12,6,3 μg Glu injection into cerebellar FN,respectively),3-MPA +Glu group (12 μg Glu injection after glutamate decarboxylase inhibitor 3-MPA injection into cerebellar FN),Bic + Glu group (12 μg Glu injection into cerebellar FN after GABAAreceptor blocker Bic injection into lateral hypothalamic area). Pain threshold,abdominal withdrawal reflex (AWR)score and abdominal external oblique muscle electromyography (EMG)were used to detect visceral sensitivity,and malondialdehyde (MDA)content and superoxide dismutase (SOD)activity were measured. Results:Chronic visceral hypersensitivity rat model was successfully established. Compared with CRD group,pain threshold was significantly increased (P＜0. 05),AWR score,EMG amplitude,MDA content were significantly decreased (P＜0. 05 ),and SOD activity was significantly increased in a dose-dependent manner in Glu group (P ＜0. 05 ). Compared with 12 μg Glu group,pain threshold was significantly decreased (P＜0. 05),AWR score,EMG amplitude, MDA content were significantly increased (P ＜0. 05),and SOD activity was significantly decreased in 3-MPA +Glu group,Bic+Glu group (P＜0. 05). Conclusions:Glu injection into cerebellar FN can significantly reduce the visceral sensitivity in rats. The mechanism may be that Glu in cerebellar FN produces GABA via glutamate decarboxylase,and then binding GABAAreceptor in lateral hypothalamic area,resulting in increased intestinal mucosal antioxidant capacity, thereby reducing visceral hypersensitivity.
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Objective To investigate the effect of systemic administration of gabapentin on the expression of Nrf2 in dorsal root ganglion neurons in a rat model of diabetic neuropathic pain (DNP). Methods 60 male SD rats weighing 200-220 g were randomly divided into 4 groups (n= 15 each): control group (group C), DNP group, saline group (SC + DNP group) and gabapentin group ( GBP + DNP group). Diabetes was induced with streptozocin (70 mg/ kg) subcutaneously. Paw withdrawal mechanical threshold ( PWMT) and paw withdrawal thermal latency (PWTL) were measured at 1d before and 3,7,10,14,21, and 28 d after streptozocin injection, and 21 and 28 d after administration of gabapentin (50 mg·kg-1 ·d-1 ,once) intraperitoneally. Saline and gabapentin (50 mg·kg-1 · d-1 ) were given intraperitoneally once a day for 7 d starting from 15 d after streptozocin injection in saline and gabapentin groups respectively. The expression of Nrf2 was determined at 21 d after streptozocin injection by immune-histochemistry and Western blot. Results Compared with group C, PWMT ( 3. 95 ± 0. 57) was significantly decreased, PWTL(6.3 ± 0.81) was significantly shorten, Nrf2 in expression was significantly decreased in DNP, SC+DNP and group (P<0.05). Compared with SC+DNP group, PWMT(8.2 ± 0.79) was significantly increased, PWTL(9.7 ± 1.13) was significantly prolonged, Nrf2 expression was significantly increased in GBP+DNP group (P<0.05). There was no significant difference in the parameters mentioned above between DNP and SC+DNP group (P>0.05). Conclusion Systemic administration of gabapentin attenuates diabetic neuropathic pain by enhancing the expression of Nrf2 in DRG neurons.
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OBJECTIVE: To evaluate the antibacterial activity of levofloxacin, moxifloxacin and nemonoxacin against Staphylococcus aureus in vitro. To assesse the impact of gyrA and parC genes mutant on resistance for quinolones and the sequences of gyrA and parC genes for three quinolones. METHODS: The MICs of 50 S. aureus were detected by agar dilution method. The MIC and MPC against four S. aureus which were special gene mutations were detected by agar dilution method. Based on these results, bacterial recovery growth curve of levofloxacin, moxifloxacin and nemonoxacin were traced. RESULTS: Nemonoxacin demonstrated activities 8- to 32- fold more potent(MICs at which 90% of isolates were inhibited, 0.5 μg·mL-1) than those of moxifloxacin(MIC90, 2 μg·mL-1) and levofloxacin (MIC90, 16 μg·mL-1) against 50 S. aureus.In condition of the same drug concentrations, the bacterial recovery growth ratios of nemonoxacin was the lowest, while levofloxacin's was the highest. RN450A3 recovery growth ratio was highest compared with other mutant bacterial strains, while RN450 recovery growth ratio was lowest. CONCLUSION: The antibacterial activities of nemonoxacin, moxifloxacin and levofloxacin against S. aureus in vitro are:nemonoxacin> moxifloxacin >levofloxacin. Compared with levofloxacin and moxifloxacin, nemonoxacin inhibits bacteria in a lower concentration, and nemonoxacin is utterly efficacious with different genes mutant strains.The target preference of levofloxacin may be the parC gene of topoisomerase IV, while moxifloxacin and nenomoxacin can almost act on the gyrA and parC gene at the same time.
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Aim To investigate the effects of metformin on phospho-signal transducers and activators of transcription 3(p-STAT3) expression in the spinal dorsal horn in rats with bone cancer pain(BCP).Methods Healthy female SD rats weighing 200~220 g were randomly divided into four groups(n=12 each): Sham+NS, Sham+Metformin, BCP+NS, BCP+Metformin groups.Normal saline or metformin(200 mg·kg-1) was given intraperitoneally once a day at 7~14 day after surgery in four groups.Mechanical withdrawal threshold(MWT) was measured on-1, 3, 5, 7, 10, 12, 14 day after BCP.The L4-6 segments of spinal cords were used to detect the expression of p-STAT3 by Western blot and immunohistochemical staining technique after the behavioral test was completed on day 14.Results Intraperitoneal injection of metformin reversed hyperalgesia and suppressed the expression of p-STAT3 in BCP rats.Conclusion Metformin can attenuate BCP by inhibiting the expression of p-STAT3 in the spinal dorsal horn.
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Objective To evaluate the effects of midazolam pretreatment on inflammatory responses and cell apoptosis during intestinal ischemia-reperfusion (I/R) in mice.Methods Thirty healthy male Kunming mice,weighing 18-22 g,were equally and randomly divided into 3 groups using a random number table:sham operation group (S group),I/R group,and midazolam pretreatment group (M group).Intestinal I/R was produced by occlusion of the superior mesenteric artery for 20 min followed by reperfusion.In group M,midazolam 1 mg/kg was injected intraperitoneally,and intestinal I/R was produced 30 min later.At 24 h of reperfusion,the mice were sacrificed,and intestinal tissues were removed for microscopic examination and for determination of the expression of interleukin-6 (IL-6),tumor necrosis factor-alpha (TNF-α) and caspase-3.Intestinal damage was assessed and scored according to Chiu.Results Compared with group S,Chiu's scores were significantly increased,and the expression of IL-6,TNF-α and caspase-3 was significantly up-regulated in I/R and M groups (P＜0.05).Compared with group I/R,Chiu's scores were significantly decreased,and the expression of IL-6,TNF-α and caspase-3 was significantly down-regulated in group M (P＜0.05).Conclusion Midazolam pretreatment can reduce intestinal I/R injury,and the mechanism is related to inhibition of inflammatory responses and cell apoptosis in mice.
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Objective To evaluate the effect of duloxetine on the expression of Toll?like receptor 4 (TLR4) in the spinal dorsal horn in a rat model of diabetic neuropathic pain (DNP). Methods Type 2 di?abetes mellitus was induced by high?fat and high?sucrose diet and intraperitoneal streptozotocin ( STZ) 35 mg∕kg in male Sprague?Dawley rats, aged 2 months, weighing 180-220 g. Seventy?five rats with type 2 di?abetes mellitus were randomly divided into 5 groups ( n=15 each ) using a random number table: group DNP, DNP + normal saline group (group DNP+NS), and DNP + duloxetine 5, 10 and 20 mg∕kg groups (DNP+D5, DNP+D10, DNP+D20 groups). Another normal 15 rats were selected and served as control group ( group C) . Duloxetine 5, 10 and 20 mg∕kg were injected intraperitoneally once a day for 14 consecu?tive days starting from 15 days after administration of STZ in DNP+D5 , DNP+D10 and DNP+D20 groups, respectively. The equal volume of normal saline was given instead in group DNP+NS. The mechanical paw withdrawal threshold ( MWT) and thermal paw withdrawal latency ( TWL) were measured on the day before STZ administration and 14, 17, 21 and 28 days after STZ administration. After the last measurement of pain threshold, the L4?6 segments of the spinal cord were removed for determination of the expression of TLR4 by immuno?histochemistry and Western blot. Results Compared with group C, the MWT was signif?icantly decreased, TWL was shortened, and the expression of TLR4 was up?regulated in DNP, DNP+D5, DNP+D10 and DNP+D20 groups (P0?05) . Conclusion The mechanism by which duloxetine attenuates DNP is related to down?regulated expression of TLR4 in the spinal dorsal horn of rats.
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Objective To evaluate the role of extracellular signal-related kinase (ERK) 1/2 signal transduction pathway at the supraspinal level in maintenance of neuropathic pain in mice.Methods Sixty-four Kunming mice,aged 2 months,weighing 18-20 g,were randomly divided into 4 groups (n =16 each):sham operation group (group S),chronic constrictive injury (CCI) group; CCI + U0126 (MEK inhibitor) group; CCI + dimethyl sulfoxide (DMSO) group.Neuropathic pain was induced by CCI.The sciatic nerve was exposed and 4 loose ligatures were placed on the sciatic nerve at 1mmintervals with 4-0 silk thread in CCI,CCI + U0126 and CCI +DMSO groups.On 5 days after CCI,5 μg U0126 (in 5 μl of 5％ DMSO) and 5％ DMSO 5 μl were injected into the lateral cerebral ventricle over 10 s in CCI + U0126 and CCI + DMSO groups,respectively,and the time of.needle retaining was 20 s.Paw withdrawal threshold to mechanical stimulation with yon Frey filament (MWT) and paw withdrawal latency to thermal stimulation (TWL) were measured before operation (baseline),before intracerebroventricular injection (T1),and at 30 min and 2,6,12 and 24h after intracerebroventricular injection (T2-6).Resuits Compared with group S,MWT was significantly decreased and TWL was shortened at T1-6 in CCI and CCI +DMSO groups,and at T1 in CCI + U0126 group (P ＜ 0.05),while no significant change in MWT and TWL was found at T2-6 in group CCI + U0126 (P ＞ 0.05).Compared with group CCI,MWT was significantly increased and TWL was prolonged at T2-6 in group CCI + U0126 (P ＜ 0.05),while no significant change in MWT and TWL was found in group CCI + DMSO (P ＞ 0.05).Conclusion ERK1/2 signaling transduction pathway at the supraspinal level is involved in maintenance of neuropathic pain in mice.