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。     

GABA_A受体对鞘内注射氧化槐定碱镇痛作用的影响

观察氧化槐定碱(oxysophoridine,OSR)鞘内注射(intrathecal injection,ith)的镇痛作用并探讨与GABAA受体相关的作用机制。采用小鼠温浴法测定痛阈,观察OSR(ith)的镇痛作用及GABAA受体激动剂和拮抗剂对OSR镇痛作用的影响;采用免疫组化法检测OSR对小鼠脊髓背角GABAARα1蛋白表达的影响。结果显示,OSR(12.5和6.25 mg·kg-1,ith)能明显延长热甩尾潜伏期(P<0.05,P<0.01),痛阈提高率达68.45%。GABA和蝇蕈醇(MUS)与OSR有协同镇痛作用,印防己毒素(PTX)和荷包牡丹碱(BIC)能拮抗OSR的镇痛作用。OSR(12.5 mg·kg-1,ith)可使脊髓背角GABAARα1表达明显增多(P<0.01)。结果提示,OSR(ith)具有明显的镇痛作用,脊髓GABAA受体参与了OSR的镇痛机制。     

侧脑室微量注射NMDA受体拮抗剂对神经病理疼痛的作用

目的:观察大鼠侧脑室微量注射N-甲基-D-天冬门氨酸(N-methyl-D-aspartate,NMDA)受体拮抗剂对神经病理性疼痛的影响,探讨脊髓上水平镇痛的机制,为临床上开发新的镇痛药物提供实验依据.方法:建立大鼠坐骨神经结扎(partial scicticnerve ligature,PSL)神经病理性疼痛模型,采用压爪-缩腿法和辐射热缩腿法测定大鼠的机械痛阈和热痛阈,观测侧脑室微量注射MK-801(NMDA受体非竞争性拮抗剂)与APV(NMDA受体竞争性拮抗剂)对神经病理性疼痛模型大鼠痛阈的影响.结果:PSL模型大鼠术后数小时痛阈即明显降低(P＜0.05),出现机械痛敏和热痛敏.侧脑室微量注射MK-801(5 nmol)、APV(2 nmol)后,大鼠机械痛阈和热痛阈明显升高,痛敏现象明显减轻(P＜0.05).结论:NMDA受体在中枢脊髓上水平与痛觉的形成和维持过程中可能起重要的作用.     

东亚钳蝎毒素多肽BmK AS-1对大鼠皮肤痛觉的影响

观察东亚钳蝎 ( Bm K)毒素纯化组分 Bm K F-1 - 3,Bm K F- 1 - 3- 2和 Bm K AS- 1 ( Bm K F- 1 - 3- 2 - 1 )中枢和外周给药对大鼠皮肤痛觉的影响 .方法采用局部皮肤感受野给药 ,以强电流刺激大鼠后肢趾部诱发半膜半腱肌发放 C反应 ,观察对外周神经系统的镇痛作用 ;经脊髓蛛网膜下腔给药 ,以大鼠足跖辐射热痛阈的变化为中枢镇痛效应的观察指标 .实验结果显示 Bm K F- 1 - 3,Bm K F- 1 - 3- 2和 Bm KAS- 1抑制 50 % C反应的剂量为 40 ,2 8.3和 1 0μg,且抑制作用不能被纳洛酮翻转 ;Bm K F- 1 - 3ith无明显提高大鼠足跖辐射热痛阈的作用 ,而 Bm KAS- 1 ith则可显著提高大鼠足跖辐射热痛阈 ,其提高 1 50 %痛阈的剂量约为 1 .2μg,纳洛酮同样对Bm K AS- 1的中枢镇痛效应无翻转作用 .结果提示东亚钳蝎毒素纯化组分 Bm K AS- 1可提高大鼠皮肤痛阈 ,其作用机理有别于阿片肽类物质 .     

脊髓α1受体介导的升压效应

目的 探讨脊髓内α肾上腺素能受体对平均动脉血压的调控作用。方法 在完整和颈1横断的大鼠,脊髓蛛网膜下腔注射(ith)选择性α1受体激动剂去氧肾上腺素后对血压和心率进行观察记录。结果 (1)在完整大鼠ith选择性α1受体激动剂去氧肾上腺素后引起血压显著升高和心率明显增快。(2)在颈1横断脊髓的大鼠,ith相同剂量的去氧肾上腺素也引起显著的升压效应。(3)在颈1横断脊髓的大鼠,ithα受体阻断剂妥拉苏林可使ith去氧肾上腺素的升压效应减弱55．1％。(4)在选择性α1受体阻断剂派唑嗪预处理后能使ith去氧肾上腺素的升压效应减弱91．1％。结论 在脊髓水平存在有由α1受体调控的升压机制。     

脊髓以上多巴胺D_2受体介导左旋四氢巴马汀的镇痛作用

目的:研究DA受体与左旋四氢巴马汀(l-THP)镇痛作用的关系,以阐明l-THP的镇痛机制。方法:腹腔(ip)与鞘内(ith)给药,以大鼠甩尾反应观测热伤害性致痛阈。结果:ip l-THP或D_2受体拮抗剂螺哌隆产生剂量依赖性镇痛效应,并能被D_2受体激动剂喹吡罗翻转,但不被纳洛酮翻转。而ithl-THP或螺哌隆无镇痛效应,但它们能拮抗ith喹吡罗引起的镇痛效应。结论:激动脊髓D_2受体或阻滞脊髓以上水平D_2受体均产生镇痛效应;l-THP镇痛作用通过阻滞脊髓以上D_2受体实现。     

丙泊酚镇痛作用及其与阿片受体的关系

目的观察丙泊酚在亚睡眠剂量时对大鼠的抗伤害作用及其与阿片受体的关系。方法选用成年雄性Wistar大鼠,通过甩尾（TFL）、电刺激鼠尾嘶叫（TSV）和结直肠扩张（CIm）法测定动物的痛阈。观察丙泊酚20mg／kg和同时应用阿片受体拮抗剂纳洛酮1mg／kg对大鼠痛阈的影响,以等效剂量硫喷妥钠作为对照。结果丙泊酚20mg／kg显著提高TSV、CRD和TFL伤害性反应阈值。采用TSV抗伤害作用时间持续60min以上,而采用TFL和CRD抗伤害作用≤30min。等效剂量硫喷妥钠无论采用TFL、TSV或CRD都无明显提高大鼠痛阈的作用。纳洛酮1mg／kg可以拮抗或部分拮抗丙泊酚引起的抗伤害作用。结论与等效量硫喷妥钠相比,亚睡眠剂量的丙泊酚在大鼠能产生一定的镇痛效应;这种镇痛效应可能与丙泊酚间接作用于中枢阿片受体有关。     

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     

中央灰质内微量注入纳洛酮对尾核镇痛作用的影响

上海第一医学院通过对家兔进行专一性阿片受体阻断剂——纳洛酮脑内注射,探讨尾核镇痛作用与内啡呔的关系。用钾离子测痛法,测定兔耳尖皮肤痛阈。尾核刺激参数为强度100～200微安,波宽0.3～0.5毫秒,频率4～5次/秒。     

大鼠脑室或脊髓蛛网膜下腔注射八肽胆囊收缩素抗血清翻转吗啡耐受

连续6天给大鼠皮下注射递增剂量的盐酸吗啡(5～30mg/kg),则吗啡镇痛效果逐渐减弱,产生耐受。给吗啡耐受的大鼠侧脑室(icv)注射八肽胆囊收缩素(CCK-8)抗血清2μl,可使吗啡耐受作用被翻转50％(P<0.001)。给吗啡耐受的动物以电针刺激,表明电针与吗啡镇痛两者之间有交叉耐受。icv注射CCK-8抗血清可使电针交叉耐受翻转50％以上(P<0.001)。脊髓蛛网膜下腔(ith)注射CCK-8抗血清也可产生类似的作用,但不如icv注射的明显。单独icv或ith注射CCK-8抗血清对痛阈无显著影响。以上结果表明中枢神经系统CNS)中CCK-8可能参与吗啡耐受的形成机理。     

大鼠蛛网膜下腔联合注射kappa受体激动剂和NMDA受体拮抗剂协同镇痛

以大鼠热辐射甩尾潜伏期为测痛指标，蛛网膜下腔（ｉｔ）联合注射非镇痛剂量的ｋａｐｐａ阿片受体激动剂强啡肽（ｄｙｎｏｒｐｈｉｎ，Ｄｙｎ）Ａ－（１－１３）５ｎｍｏｌ或Ｕ５０４８８Ｈ（ｔｒａｎｓ－（±）－３，４－ｄｉｃｈｌｏｒｏ－Ｎ－ｍｅｔｈｙｌ－［２－（１－ｐｙｒｒｏｌｉｄｉｎｙｌ）－ｃｙｃｌｏｈｅｘｙｌ］－ｂｅｎｚｅｎｅａｃｅｔａｍｉｄｅ）１００ｎｍｏｌ和Ｎ－ｍｅｔｈｙｌ－Ｄ－ａｓｐａｒｔａｔｅ（ＮＭＤＡ）受体拮抗剂ＤＬ－２－ａｍｉｎｏ－５－ｐｈｏｓｐｈｏｎｏｖａｌｅｒｉｃａｃｉｄ（ＡＰｖ）１０ｎｍｏｌ或ｋｙｎｕｒｅｎｉｃａｃｉｄ（ＫＹＮ）５０ｎｍｏｌ有显著的协同镇痛效应，其效应与ＮＭＤＡ受体拮抗剂呈一定量效关系。Ｋａｐｐａ阿片受体特异性拮抗剂ｎｏｒ－ｂｉｎａｌｔｏｒｐｈｉ－ｍｉｎｅ（ｎｏｒ－ＢＮＩ）１５ｎｍｏｌｉｔ可完全翻转ＤｙｎＡ－（１－１３）５ｎｍｏｌ和ＡＰｖ１０ｎｍｏｌ及Ｕ５０４８８Ｈ１００ｎｍｏｌ和ＫＹＮ５０ｎｍｏｌ的协同镇痛。说明协同作用是通过ｋａｐｐａ受体和谷氨酸能神经元之间的相互作用实现的。     

Bradykinin analogue blocks bradykinin-induced inhibition of a spinal nociceptive reflex in the rat

In the awake restrained rat the intrathecal (i.th.) administration of 81 pmol to 8.1 nmol of bradykinin (BK) increased reaction time to a noxious radiant heat stimulus. The enhancement of tail-flick latency peaked at 1 min and returned to the basal level 11-16 min after BK administration. Behavioural responses were observed as early as 5 s following peptide administration and lasted for 30-45 s. When BK was given after prior i.th. administration of 6.1 nmol of [Thi5,8, D-Phe7]BK, an antagonist of BK at the B2-receptor, the increase in latency was significantly attenuated. The analogue [Leu8]BK-(1-8) (10.3 nmol), an antagonist of BK at the B1-receptor, failed to modify the BK-induced antinociception. The two analogues alone and the fragment BK-(1-8), a potent stimulant of B1-receptors for BK, failed to alter reaction time and only the B2-receptor antagonist reduced BK-induced behavioural responses. These results suggest that BK may play a role through the activation of a B2-receptor type in a spinal sensory pathway subserving pain.     

Brain but not spinal NR2B receptor is responsible for the anti-allodynic effect of an NR2B subunit-selective antagonist CP-101,606 in a rat chronic constriction injury model

In order to examine the site of action of an NR2B subtype-selective NMDA antagonist CP-101,606, we investigated its analgesic effect in a rat model of neuropathic pain at various routes of administration. Mechanical allodynia was induced by chronic constriction injury (CCI) of the sciatic nerve in male Sprague-Dawley rats. Subcutaneous treatment of the animals with CP-101,606 at 10 mg/kg significantly inhibited CCI-induced mechanical allodynia. Intracerebroventricular injection of CP-101,606 at 10, 30 and 100 nmol also inhibited the mechanical allodynia in a dose-dependent manner, the statistically significant effect being achieved at the highest dose tested (100 nmol) without producing any behavioral abnormalities. However, intrathecal injection of CP-101,606 at a dose of 300 nmol failed to inhibit CCI-induced allodynia. A receptor binding assay using rat forebrain and spinal cord membrane preparations demonstrated that [3H]CP-101,606 bound to the brain NR2B receptor with a greater extent compared to the spinal cord one. These findings suggest that the anti-allodynia effect of CP-101,606 is ascribable to blockade of NR2B receptors at the brain, but not at the spinal cord. In contrast, intrathecal injection of a non-selective NMDA antagonist, memantine, significantly inhibited CCI-induced mechanical allodynia at a dose of 300 nmol, indicating the difference in the site of action between the non-selective NMDA antagonist and the NR2B-specific NMDA antagonist.     

Analgesic profile of centrally administered 2-methylserotonin against acute pain in rats

The present study examined patterns of analgesia by intracerebroventricular (i.c.v.) or intrathecal (i.t.) administration of the serotonin 5-HT3 receptor agonist, 2-methylserotonin (1-100 micrograms) against acute thermal, mechanical or formalin-induced chemo-inflammatory pain in male rats. Neither i.c.v. or i.t. 2-methylserotonin produced motoric, sedative or respiratory effects. I.c.v. 2-methylserotonin was not analgesic at any dose in the pain assays employed. I.t. 2-methylserotonin produced dose-related analgesia in the formalin test with significant effects at 20-100 micrograms doses. In contrast, only the 100 micrograms dose of 2-methylserotonin produced analgesia against thermal pain, and analgesia was not observed at any dose in the mechanical pain test. The effects of 2-methylserotonin (100 micrograms) in the formalin test were attenuated by pretreatment (10 micrograms i.t.) with the 5-HT3 receptor antagonist MDL-72222, opioid antagonist naloxone or GABA antagonist bicuculline; the 5-HT2-receptor antagonist ketanserin or 5-HT1 receptor antagonist mianserin did not affect 2-methylserotonin-induced analgesia. In the thermal test, i.t. pretreatment with MDL-72222, ketanserin, naloxone or bicuculline, but not mianserin, reduced analgesic effects of 2-methylserotonin (100 micrograms i.t.). These findings suggest that spinal 5-HT3, opioid and GABA receptor systems interact to mediate acute chemo-inflammatory pain, and implicate the interaction of these systems with 5-HT2 receptor substrates in analgesia against acute thermal nociception.     

大鼠蛛网膜下腔联合注射kappa受体激动剂和NMDA受体拮抗剂协同镇痛

以大鼠热辐射甩尾潜伏期为测痛指标,蛛网膜下腔(it)联合注射非镇痛剂量的kappa阿片受体激动剂强啡肽(dynorphin,Dyn)A-(1-13)5nmol或U50488H(trans-(±)-3,4-dichloro-N-methyl-[2-(1-pyrrolidinyl)-cyclohexyl]-benzeneacetamide)100nmol和N-methyl-D-aspartate(NMDA)受体拮抗剂DL-2-amino-5-phosphonovalericacid(APv)10 nmol 或 kynurenicacid (KYN) 50 nmol 有显著的协同镇痛效应,其效应与NMDA受体拮抗剂呈一定量效关系。Kappa阿片受体特异性拮抗剂nor-binaltorphi-mine(nor-BNI)15nmolit可完全翻转Dyn A-(1-13)5nmol和APv10nmol及U50488H100nmol和KYN50nmol的协同镇痛。说明协同作用是通过kappa受体和谷氨酸能神经元之间的相互作用实现的。     

Spinal 5-HT-receptors and tonic modulation of transmission through a withdrawal reflex pathway in the decerebrated rabbit.

1. In decerebrated, non-spinalized rabbits, intrathecal administration of either of the selective 5-HT1A-receptor antagonists (S)WAY-100135 or WAY-100635 resulted in dose-dependent enhancement of the reflex responses of gastrocnemius motoneurones evoked by electrical stimulation of all myelinated afferents of the sural nerve. The approximate ED50 for WAY-100635 was 0.9 nmol and that for (S)WAY-100135 13 nmol. Intrathecal doses of the antagonists which caused maximal facilitation of reflexes in non-spinalized rabbits had no effect in spinalized preparations. 2. In non-spinalized animals, intravenous administration of (S)WAY-100135 was significantly less effective in enhancing reflexes than when it was given by the intrathecal route. 3. When given intrathecally, the selective 5-HT 2A/2C-receptor antagonist, ICI 170,809, produced a bellshaped dose-effect curve, augmenting reflexes at low doses (< or = 44 nmol), but reducing them at higher doses (982 nmol). Idazoxan, the selective alpha 2-adrenoceptor antagonist, was less effective in enhancing reflex responses when given intrathecally after ICI 170,809 compared to when it was given alone. Intravenous ICI 170,809 resulted only in enhancement of reflexes and the facilitatory effects of subsequent intrathecal administration of idazoxan were not compromised. 4. The selective 5-HT3-receptor blocker ondansetron faciliated gastrocnemius medialis reflex responses in a dose-related manner when given by either intrathecal or intravenous routes. This drug was slightly more potent when given i.v. and it did not alter the efficacy of subsequent intrathecal administration of idazoxan. 5. None of the antagonists had any consistent effects on arterial blood pressure or heart rate. 6. These data are consistent with the idea that, in the decrebrated rabbit, 5-HT released from descending axons has multiple roles in controlling transmission through the sural-gastrocnemius medialis reflex pathway. Thus, it appears 5-HT tonically inhibits transmission between sural nerve afferents and gastrocnemius motoneurones by an action at spinal 5-HT1A-receptors. Spinal 5-HT2A/2C-receptors may mediate a weak inhibition of transmission in the spinal cord, but more convincing evidence was obtained for their involvement in descending facilitatory tone. Further, some of the facilitatory consequences of spinal alpha 2-adrenoceptor blockade may be mediated through 5-HT2 type receptors. Spinal 5-HT3 receptors do not appear to have a major role in tonic modulation of the sural-gastrocnemius medialis reflex.     

大鼠鞘内注射AP5的抗内脏伤害作用

目的观察鞘内注射竞争性N-甲基-D-天冬氨酸（NMDA）受体拮抗剂2-氨基-5-磷酰基戊酸酯（AP5）对大鼠结直肠扩张（CRD）诱发的内脏伤害性刺激的影响及剂量关系。方法利用大鼠CRD模型诱导的内脏伤害性刺激,经鞘内引入药物,观察对腹壁撤回反射（AWR）达到3级时痛阈的影响。结果AP5剂量依赖地抑制CRD诱导的内脏伤害性刺激,并有时间作用特点。结论竞争性NMDA受体拮抗剂AP5可以抑制CRD诱导的内脏伤害性刺激,NMDA受体在内脏伤害性刺激脊髓水平的传递中起重要作用。     

Spinal alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors may mediate the analgesic effects of emulsified halogenated anaesthetics

1. The present study was designed to investigate the relationship between spinal cord alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors and the analgesic effects of emulsified halogenated anaesthetics. 2. After having established the mouse model of analgesia by intraperitoneal or subcutaneous injections of appropriate doses of emulsified enflurane, isoflurane or sevoflurane, we injected different doses of AMPA intrathecally and observed effects on the pain threshold using the hot-plate and acetic acid-induced writhing tests. 3. The results showed that intrathecal injection of AMPA (0.25, 0.5 and 1.0 ng) did not affect the pain threshold on the hot-plate test or the writhing times in conscious mice. In contrast, AMPA (0.25, 0.5 and 1.0 ng intrathecally) significantly and dose-dependently decreased the pain threshold on the hot-plate test and increased the writhing times in mice treated with emulsified anaesthetics. 4. These results suggest that spinal AMPA receptors may be important targets for the analgesic effects of emulsified enflurane, isoflurane and sevoflurane.     

GABAB receptors do not mediate the inhibitory actions of gabapentin on the spinal reflex in rats

The clinical effectiveness of gabapentin for the treatment of epilepsy, spasticity, and neuropathic pain has been established. The mechanisms responsible for those actions, however, are still not clearly understood. We have recently demonstrated that gabapentin reduces the spinal reflex in rats via mechanisms that do not involve gamma-aminobutyric acid (GABA)A receptors. In the study, we attempted to explore the involvement of GABAB receptors in gabapentin-induced inhibition of the spinal reflexes in spinalized rats. Stimulation of the dorsal root at L5 elicited the segmental mono-(MSR) and polysynaptic reflex (PSR) in the ipsilateral ventral root. The microinjection of gabapentin (1.5 and 5 nmol) into the ventral horn reduced both MSR and PSR, whereas the injection into the dorsal horn only inhibited the PSR, indicating that systemic gabapentin inhibits the MSR at the ventral horn and it inhibits the PSR at both the ventral and dorsal horns. The GABAB-receptor antagonist CGP35348 (0.5 nmol) injected into the ventral horn antagonized the inhibition of the spinal reflexes by the GABAB-receptor agonist baclofen (i.v.) but not by gabapentin (i.v.). Thus, GABAB receptors do not appear to contribute to the gabapentin-induced inhibition of the spinal reflex.