鞘内注射6-羟多巴胺、α_1受体拮抗剂对氯胺酮脊髓镇痛作用的影响

目的　在体探讨脊髓去甲肾上腺素 (NE)能神经元α1受体和氯胺酮 (Ket)脊髓镇痛的关系。方法　用热水甩尾法观察鞘内注射 (ith)氯胺酮 5 0、10 0、2 0 0 μg对小鼠甩尾潜伏期(TFL)的影响。并观察鞘内分别预先注射 6 羟多巴胺 (6 OH DA ,6 μg)、α1受体拮抗剂哌唑嗪 (Pra,5、15 μg)或特拉唑嗪(Ter,5、15 μg )对Ket(10 0 μg ,ith)脊髓镇痛的影响。 结果　Ket(5 0 μg ,ith)对小鼠TFL无影响 (P >0 0 5 ) ,而Ket(10 0、2 0 0μg ,ith)可剂量依赖性地延长小鼠TFL(P <0 0 5 )。鞘内单独注射 6 OHDA、Pra或Ter对小鼠的痛阈无影响 (P >0 0 5 )。ith 5 μgPra或Ter对Ket脊髓镇痛无影响 (P >0 0 5 ) ,而ith 6 OHDA、15 μgPra或Ter则可明显减弱Ket脊髓镇痛 (P <0 0 5 )。结论　脊髓是Ket的镇痛部位之一 ,Ket脊髓镇痛和脊髓NE神经元α1受体有关     

鞘内注射纳洛酮对小剂量丙泊酚抗内脏伤害作用的影响

目的研究丙泊酚内脏痛镇痛机制是否与脊髓阿片受体有关。方法56只成年雄性SD大鼠蛛网膜下腔埋入导管后随机均分为8组，分别鞘内预注生理盐水（NS）或纳洛酮2μg／只、4μg／只或8μg／只，再腹腔注射NS或丙泊酚10mg／kg，随后采用结直肠扩张的内脏痛实验动物模型，以腹壁明显收缩变平的最小扩张压力值作为内脏痛反应（VMR）阈值，观察大鼠60min内内脏痛阈的变化。结果单纯腹腔注射小剂量丙泊酚后，5～25min内大鼠内脏痛阈显著升高（P〈0．01），10min达高峰（％MPE=37．2％）；单纯鞘内预注不同剂量纳洛酮大鼠内脏痛阈无明显变化（P〉0．05）；先鞘内预注不同剂量纳洛酮再腹腔注射丙泊酚后，丙泊酚所致抗内脏伤害作用被不同程度的减弱。结论（1）小剂量丙泊酚对内脏伤害刺激具有抑制作用；（2）纳洛酮剂量依赖、时间依赖地拮抗丙泊酚的抗内脏伤害作用，其作用机制与脊髓阿片受体有关。     

鞘内注射荷包牡丹碱和L-烯丙基甘氨酸对氯胺酮脊髓镇痛的影响

目的　在体研究脊髓GABAA 受体和氯胺酮(Ket)脊髓镇痛的关系 ,并初步探讨突触前、后机制在其中的作用。方法　用热水甩尾法和醋酸扭体法 ,观察鞘内注射 (ith)Ket(2 5 ,5 0 ,10 0 μg)对小鼠痛阈的影响。并用热水甩尾法观察GABAA 受体拮抗剂荷包牡丹碱 (Bic ,0 .0 5 ,0 .1,0 .2 μg ,ith) ,GABA合成酶抑制剂L 烯丙基甘氨酸 (AG ,2 0 0mg·kg- 1,ip)及两药合用对小鼠基础痛阈和Ket(10 0 μg ,ith)脊髓镇痛的影响。结果　Ket可产生剂量依赖性的镇痛作用。Bicith对小鼠痛阈无明显影响 ,但可明显减弱Ket的脊髓镇痛作用。ipAG或合用Bic(0 .0 5 ,0 .1μg,ith)对小鼠痛阈都无明显影响 ,而预先AGip可明显减弱Ket脊髓镇痛作用 ;且AGip后 ,Bic(0 .1μg ,ith)对Ket脊髓镇痛无明显拮抗作用。 结论　脊髓是Ket的镇痛部位之一 ,Ket的镇痛作用可能和Ket促进脊髓释放GABA有关。     

鞘内注射硫酸镁和吗啡对切口痛大鼠脊髓背角p-αCaMK Ⅱ表达的影响

目的观察鞘内注射(it)硫酸镁(MgSO4)和吗啡对切口痛大鼠脊髓背角磷酸化钙—钙调蛋白依赖性蛋白激酶Ⅱα(p-αCaMKⅡ)表达的影响。方法所有大鼠术前8d鞘内置管,用机械缩足反射阈值、热缩足潜伏期和累计疼痛评分来评价大鼠疼痛行为学变化;用免疫组织化学和Western blot法来测定吗啡和硫酸镁对大鼠脊髓背角p-αCaMKⅡ表达的影响。结果术前或术后30minit吗啡5μg或MgSO4188μg和吗啡2.5μg使术后2h的机械性缩爪阈值(MWT)和热刺激缩爪阈值(TWL)明显延长(P<0.01),累积疼痛评分明显降低(P<0.01);术前30minitMgSO4375μg或吗啡5μg或MgSO4188μg和吗啡2.5μg使大鼠术后2h脊髓背角p-αCaMKⅡ表达明显减少(P<0.05)。结论在大鼠切口痛模型中,it吗啡5μg或MgSO4188μg和吗啡2.5μg具有确切的抗伤害作用,其抗伤害作用可能与抑制脊髓背角p-αCaMKⅡ表达有关。     

鞘内联合应用吗啡和氯胺酮对神经痛大鼠脊髓P物质表达的影响

目的研究鞘内联合应用吗啡和氯胺酮对神经痛大鼠脊髓P物质表达的影响。方法12只Wistar大鼠,体质量220~260 g,制备坐骨神经结扎模型并鞘内置管,随机分为4组(n=3):B组为空白对照组;C组鞘内注射生理盐水10μL;M组鞘内注射吗啡20μg;KM组鞘内注射吗啡10μg和氯胺酮25μg。坐骨神经结扎术后第4天开始鞘内给药,1次/d,连续7 d。用药7 d后处死大鼠,取腰段脊髓,免疫组化法测定脊髓P物质的含量。结果C组P物质表达明显低于B组(P<0.05)和KM组(P<0.01);KM组P物质表达明显高于M组(P<0.05)。结论鞘内联合应用吗啡和氯胺酮的抗伤害性作用,可能与其增加脊髓背角P物质的含量有关;脊髓背角P物质含量减少,可能介导慢性坐骨神经损伤后的痛敏持续状态。     

鞘内注射P物质拮抗氯胺酮的抗伤害作用

目的观察脊髓P物质对氯胺酮抗伤害作用的影响。方法在小鼠福尔马林实验中,结合行为学和Fos蛋白表达,观察鞘内注射(it)不同剂量的P物质对氯胺酮抗伤害作用的影响。结果氯胺酮20、30mg·kg-1ip可剂量依赖性地减少小鼠舔足时间(P<0.05)。P物质0.25、0.5ngit可增加注射氯胺酮小鼠舔足时间(P<0.05)。小鼠注射福尔马林后,注射侧脊髓背角Fos免疫样(Foslikeimmunoreactive,FLI)阳性神经元数量明显增加(P<0.01),预先给于氯胺酮30mg.kg-1ip可以明显减少脊髓背角FLI阳性神经元数量(P<0.01),而P物质0.5ngit能明显削弱氯胺酮对脊髓背角Fos表达的抑制(P<0.01)。结论鞘内注射P物质能拮抗脊髓水平氯胺酮抗伤害作用。     

鞘内注射p-MPPF对异氟烷镇痛作用的影响

目的探讨异氟烷(isoflurane,Iso)镇痛作用与小鼠脊髓5-HT1A受体的关系。方法昆明种小鼠腹腔注射Iso建立镇痛模型。分别以甩尾法、热板法、醋酸扭体法(15min内)评估小鼠鞘内注射5-HT1A受体拮抗剂p-MPPF(6μg和3μg)对Iso镇痛作用的影响。结果单独鞘内注射p-MPPF对小鼠甩尾潜伏期、热板痛阈、扭体次数无影响(P>0.05)。与Iso镇痛组(Iso组)相比,合用药组(Iso+M6组,Iso+M3组)甩尾潜伏期与热板痛阈均缩短(P<0.01或P<0.05);Iso+M6组扭体次数较Iso组增多(P<0.05),Iso+M3组无变化(P>0.05)。结论 Iso体表镇痛作用与激动小鼠脊髓5-HT1A受体密切相关。     

GABA_A受体部分介导丙泊酚在大鼠脊髓水平的抗伤害作用

目的研究丙泊酚在脊髓水平对大鼠伤害性感受的影响及GABAA受体在其中可能的作用。方法Sprague-Daw-ley(SD)♀大鼠随机分组,丙泊酚(Propofol,Pro)和荷包牡丹碱(B icucu lline,B ic)采用鞘内注射(ith)。行为学实验采用热板法和福尔马林实验,分别以舔后爪潜伏时间(Hot-p latelatency,HPL)和疼痛(累计)评分为指标。免疫组化方法观察丙泊酚鞘内给药对福尔马林单侧足底皮下注射诱发的脊髓背角Fos蛋白表达的影响。结果行为学部分:在两种疼痛模型中,鞘内注射丙泊酚(10 g.L-1)产生镇痛作用(P<0.01)。在热板法实验中,鞘内注射丙泊酚(10 g.L-1)产生的镇痛作用在10、20、30和40 min时间点可被鞘内给予Bic(0.01 g.L-1)分别拮抗81%、55%、81%和97%(均P<0.01)。在福尔马林实验中,鞘内注射丙泊酚(10 g.L-1)减少的福尔马林疼痛评分在30 min时间点可被Bic(0.01 g.L-1)相同部位注射拮抗67%(P<0.01)。免疫组化部分:鞘内注射丙泊酚(10 g.L-1)明显减少福尔马林单侧足底皮下注射引起的大鼠同侧腰段脊髓背角各层Fos免疫反应样神经元(Fos-like immunoreactivity,FLI)阳性细胞数(P<0.01);鞘内注射丙泊酚(10 g.L-1)产生的效应可被鞘内注射Bic(0.01 g.L-1)部分拮抗(P<0.01)。结论鞘内注射丙泊酚在大鼠可产生镇痛作用;GABAA受体部分介导了丙泊酚的以上作用。     

脊髓c-Jun在NMDA受体NR2B亚基介导的大鼠吗啡镇痛耐受中的作用

目的探讨脊髓c-Jun在N-甲基-D-天冬氨酸(N-meth-yl-D-aspartate,NMDA)受体NR2B亚基介导的吗啡镇痛耐受中的作用。方法取Sprague-Dawley(SD)成年大鼠连续7 d鞘内注射吗啡10μl(1.5 g.L-1)建立慢性吗啡镇痛耐受模型。应用热水甩尾法测定甩尾潜伏期(疼痛指标)以观察痛反应变化。应用免疫组织化学染色法检测磷酸化c-Jun(p-c-Jun)和总c-Jun(t-c-Jun)的表达。结果鞘内注射吗啡7 d,可激活大鼠脊髓的c-Jun,表现为神经元内p-c-Jun表达升高;鞘内注射NR2B选择性拮抗剂10μl Ro256981(2 g.L-1)可以抑制慢性吗啡镇痛耐受时脊髓神经元c-Jun的激活,并明显拮抗吗啡镇痛耐受的形成。结论脊髓神经元c-Jun的磷酸化参与NMDA受体NR2B亚基介导的吗啡镇痛耐受。     

神经元烟碱受体与异氟烷、七氟烷催眠和镇痛作用的关系

目的探讨神经元烟碱受体(neuronal nicotinic acetyl-choline receptors,nnAChRs)与异氟烷、七氟烷催眠和镇痛作用的关系。方法建立小鼠催眠、镇痛模型后,在催醒、热板和扭体实验中分别观察侧脑室(intracerebroventricular,icv)或鞘内(intrathecal,it)注射不同剂量烟碱(nicotine,N)对小鼠睡眠时间(sleeping time,ST)、热板法痛阈(pain threshold in hot-plate test,HPPT)和扭体次数的影响。结果催醒实验中,烟碱10、20、40μgicv能够剂量依赖性地缩短异氟烷、七氟烷催眠小鼠的ST(P<0·05,P<0·01);热板实验中,烟碱5、10、15μgit对清醒小鼠HPPT没有影响(P>0·05),但能够剂量依赖性地减少异氟烷、七氟烷镇痛小鼠的HPPT(P<0·05,P<0·01);扭体实验中,皮下注射镇痛剂量的异氟烷、七氟烷后均能引起小鼠的扭体次数减少(P<0·01),但烟碱5、10、15μgit对异氟烷、七氟烷镇痛小鼠的扭体次数的影响差异均无显著性(P>0·05)。结论nnAChRs是异氟烷、七氟烷催眠作用的重要靶位;也是异氟烷、七氟烷抗热刺激伤害的重要靶位,但与其抗化学内脏痛作用关系不大。     

Antagonism by phenoxybenzamine of the analgesic effect of morphine injected into the nucleus reticularis gigantocellularis of the rat.

Effects of some monoaminergic blockers on the analgesia induced by morphine microinjection into the nucleus reticuloris gigantocellularis were studied in rats. Pretreatment with phenoxybenzamine (0.1–1 mg/kg i.p.), but neither propranolol (5 mg/kg i. p.) nor methysergide (i mg/kg i.p.), suppressed the analgesic effect of morphine. The morphine analgesia was also inhibited by intrathecal administration of phenoxybenzamine (10 μg) at the level of the lumbar spinal cord. These results emphasise the important role of the spinal noradrenergic system, mediated by α-adrenoceptors, in the production of analgesia by morphine injected into the nucleus reticularis gigantocellularis.     

Effects of intrathecal 6-hydroxydopamine, α1 and α2 adrenergic receptor antagonists on antinociception of propofol in mice

AIM: To investigate the relationship between spinal cord norepinephrine, alpha1 and alpha2 adrenergic receptors and antinociception of propofol in mice. METHODS: Kunming mice were used. Antinociceptive tests were investigated with the tail-immersion test and the acetic acid-induced writhing test. The effects of subcutaneous (sc), intrathecal (ith) and intracerebroventricular (icv) injection propofol on pain threshold were observed. The influences of pretreatment with ith 6-hydroxydopamine, alpha1R antagonist prazosin, or alpha2R antagonist yohimbine on the antinociception of propofol were studied. RESULTS: Significant antinociception was produced by propofol (25, 50 mg/kg, sc) and propofol (20, 40 microg, ith) in tail-immersion test and acetic the acid-induced writhing test (P<0.05 or P<0.01). Icv propofol (10, 20, and 40 microg) did not produce any effect on pain threshold in mice (P>0.05). The 6-hydroxydopamine (5 and 10 microg), prazosin (5 and 10 microg), or yohimbine (5 and 10 microg) ith alone did not affect basal tail-flick latency (TFL) in conscious mice, but significantly reduced the TFL as measured by tail-immersion test in propofol (50 mg/kg, sc)-treated mice, compared with basal TFL and vehicle groups (P<0.05 or P<0.01). CONCLUSION: The spinal cord is a target of propofol antinociception. In mice propofol antinociception is partly mediated by spinal norepinephrine, alpha1R and alpha2R.     

Noradrenergic and purinergic involvement in spinal antinociception by 5-hydroxytryptamine and 2-methyl-5-hydroxytryptamine.

The adrenergic involvement in spinal antinociception by 5-hydroxytryptamine (5-HT) and 2-methyl-5-hydroxytryptamine (2-Me-5-HT) was examined using the alpha-adrenoceptor antagonists phentolamine, yohimbine and prazosin, and the neurotoxin 6-hydroxydopamine. Intrathecal pretreatment with phentolamine and yohimbine (7.5-30 micrograms), but not prazosin (30 micrograms), reduced the action of 5-HT and 2-Me-5-HT in both the tail flick and hot plate tests. Pretreatment with 6-hydroxydopamine (100 micrograms) reduced (5-HT) or increased (2-Me-5-HT) antinociception in the hot plate test, while tail flick responses were largely unaffected. In other experiments, 8-phenyltheophylline, an adenosine receptor antagonist, reduced the action of 5-HT, but not 2-Me-5-HT, in both tests. These results indicate that (a) antinociception by both 5-HT and 2-Me-5-HT involves some form of interaction with spinal alpha 2-adrenoceptors, but the nature of the interaction for these two agents is different because only 5-HT is dependent on endogenous noradrenaline, (b) release of adenosine from the spinal cord contributes to spinal antinociception by 5-HT but not by 2-Me-5-HT.     

Interactions between Substance P and Norepinephrine in the Regulation of Nociception in Mouse Spinal Cord

Abstract: This study examined interactions between effects of the undecapeptide substance P and norepinephrine and the α-adrenoceptor agonist clonidine in the mouse spinal cord. All compounds were injected into the lumbar subarachnoid space, and effects on the tail-flick reflex and the behavioural response to intrathecal substance P were evaluated. The tail-flick response latencies were markedly increased 5–20 min. after intrathecal application of norepinephrine (0.0125–0.1 μg) or clonidine (0.0125–0.1 μg). The actions of both intrathecal norepinephrine (0.025 μg) and intrathecal clonidine (0.025 μg) were significantly attenuated when substance P (5 μg) was given intrathecally 55 and 45 min. before the agonists. There was a significant relationship between the tail-flick response latencies and the tail skin temperature. However, the tail-flick results were not due to changes in the skin temperature. Intrathecally applied substance P (10 ng) produced a response consisting of biting of the caudal part of the body and a few hindlimb scratches. The number of bites was significantly reduced 5 min. after injection of norepinephrine (0.1 μg) or clonidine (0.05–0.1 μg), but the number of scratches was unchanged. The data show that increased stimulation of spinal α-adrenoceptors inhibits a spinal nociceptive reflex as well as the action of substance P in the spinal cord. Substance P modulates the action of α-adrenoceptor agonists on the tail-flick reflex, which may tentatively be explained by downregulation of α-adrenoceptors by substance P.     

Water soluble fraction (<10 kDa) from bee venom reduces visceral pain behavior through spinal alpha 2-adrenergic activity in mice

We have previously shown that subcutaneous bee venom (BV) injection reduces visceral pain behavior in mice, but it is not clear which constituent of BV is responsible for its antinociceptive effect. In the present study, we now demonstrate that a water-soluble subfraction of BV (BVA) reproduces the antinociceptive effect of BV in acetic acid-induced visceral pain model. We further evaluated three different BVA subfractions that were separated by molecular weight, and found that only the BVAF3 subfraction (a molecular weight of <10 kDa) produced a significant antinociceptive effect on abdominal stretches and suppressed visceral pain-induced spinal cord Fos expression. Injection of melittin (MEL), a major constituent of BVAF3, also produced a visceral antinociception. However, melittin's antinociception was completely blocked by boiling for 10 min at 100 degrees C, while boiling either whole BV or BVAF3 did not prevent their antinociception. The antinociceptive effect of BVAF3 was completely blocked by intrathecal pretreatment with the alpha2-adrenoceptor antagonist, yohimbine (YOH), while intrathecal pretreatment with the opioid antagonist, naloxone (NAL) or the serotonin antagonist, methysergide, had no effect. These data demonstrate that BVAF3 is responsible for the visceral antinociception of whole BV and further suggest that this effect is mediated in part by spinal alpha2-adrenergic activity.     

鞘内注射士的宁对丙泊酚镇痛作用的影响

目的　探讨脊髓甘氨酸受体与丙泊酚镇痛作用的关系。方法　以热板法和扭体法测小鼠痛阈的变化 ,观察鞘内注射 (it)不同剂量士的宁对丙泊酚小鼠痛阈的影响。结果　丙泊酚 12 5mg·kg-1腹腔注射 (ip)对小鼠热板法痛阈 (painthresholdinhot platetest,HPPT)无影响 (P >0 0 5 ) ,2 5、5 0mg·kg-1可使小鼠HPPT增加 (P <0 0 5 ) ;丙泊酚 5mg·kg-1静脉注射 (iv)对小鼠扭体次数无影响 (P >0 0 5 ) ,7 5、10mg·kg-1iv可使小鼠扭体次数减少 (P <0 0 5 )。士的宁0 2 5 μgit对丙泊酚小鼠 (5 0mg·kg-1,ip)HPPT无影响 (P>0 0 5 ) ;0 5、0 75、1 0 μgit均可减少丙泊酚小鼠的HPPT(P <0 0 5 )。士的宁 0 2 5、0 5、0 75、1 0 μgit对丙泊酚小鼠 (10mg·kg-1,iv)扭体次数均无影响 (P >0 0 5 )。结论　丙泊酚在热板法和扭体法中产生不同的镇痛作用 ,前者可能与脊髓甘氨酸受体有关 ,后者与脊髓甘氨酸受体关系不大