宾赛克嗪拮抗M和N胆碱受体的特征及其抗胆碱酯酶抑制剂的毒性效应

目的评价宾赛克嗪(benthiactzine)对胆碱受体功能拮抗作用及其对有机磷农药中毒的抗毒效应,并与阿托品比较。方法①以烟碱诱发小鼠惊厥,离体豚鼠回肠收缩为评价中枢和外周神经元N受体功能的指标;以槟榔碱诱发小鼠震颤为评价中枢M受体功能的指标;以槟榔碱和毛果芸香碱诱发小鼠流涎,乙酰胆碱和氧化震颤素诱发回肠收缩为评价外周M受体功能的指标;并在烟碱和毛果芸香碱联用诱发混合性震颤模型上,研究药物的药理学特点。②在DDVP染毒小鼠模型上研究药物的抗毒效应(PR值)。结果①宾赛克嗪抗槟榔碱致小鼠中枢性震颤的ED50±L95为(0.31±0.06)mg.kg-1,中枢抗M作用比阿托品(1.33±0.17)mg.kg-1强3.3倍。②宾赛克嗪抗槟榔碱和毛果芸香碱诱发小鼠流涎的ED50±L95分别为(0.38±0.09)mg.kg-1和(5.57±1.30)mg.kg-1,而阿托品分别为(0.17±0.03)mg.kg-1和(0.46±0.18)mg.kg-1,宾赛克嗪的外周抗M作用弱于阿托品。③宾赛克嗪抗烟碱诱发惊厥的ED50±L95为(2.87±0.76)mg.kg-1,具有较强的中枢抗N作用。④宾赛克嗪抗烟碱诱发回肠收缩的IC50±L95为(1.1±0.18)μmol.L-1,比阿托品(13.84±1.68)μmol.L-1强约13倍,说明宾赛克嗪具有外周神经元N受体拮抗作用。⑤宾赛克嗪抗毛果芸香碱和烟碱联用诱发小鼠震颤的ED50±L95为(2.64±0.35)mg.kg-1,比阿托品(4.95±0.65)mg.kg-1强约1倍。⑥宾赛克嗪和阿托品抗DDVP致死作用的ED50±L95分别为(2.87±0.40)mg.kg-1和(6.78±3.92)mg.kg-1;宾赛克嗪10 mg.kg-1可使小鼠抗DDVP中毒的PR值提高16.84倍,而阿托品仅能提高0.81倍。结论宾赛克嗪中枢抗M作用强于阿托品,外周抗M作用弱于阿托品,并具有中枢和外周神经元N受体拮抗作用;宾赛克嗪对敌敌畏中毒小鼠的抗毒效应明显强于阿托品。     

慢性反复给予烟碱对中枢毒蕈碱受体功能的调节作用

每天２次ｓｃ烟碱２．０ｍｇ·ｋｇ－１１０ｄ后，大鼠对烟碱诱发体温下降，转杆操作能力下降和行为惊厥的作用产生耐受，槟榔碱诱发大鼠脑电癫痫样放电的剂量下降．每天２次ｓｃ烟碱２．０和／或ｓｃ槟榔碱５．０ｍｇ·ｋｇ－１ｉｐ１４ｄ后，烟碱与槟榔碱联用可诱发大鼠大脑皮层毒蕈碱受体数目减少，并为美加明１．０ｍｇ·ｋｇ－１ｓｃ１４ｄ对抗．提示慢性反复给予烟碱可增强大鼠中枢毒蕈碱受体对其激动剂槟榔碱介导脑电癫痫样放电和受体下行性调节的敏感性．     

Characteristics of behavioral and electroence phalogram convulsion sinduced bynicotine and itsdi（＋）t

在清醒小鼠上，烟碱游离碱及其重酒石酸盐均可剂量依赖性地诱发行为和脑电惊厥．烟碱游离碱１．０ｍｇ·ｋｇ－１ｉｖ在所有受试动物上均可诱发行为惊厥伴脑电癫痫样放电，并可被神经元型Ｎ受体拮抗剂美加明拮抗，但不被Ｍ受体拮抗剂阿托品和肌肉型Ｎ受体拮抗剂加拉碘铵所拮抗．烟碱重酒石酸盐诱发行为惊厥的作用较强，但诱发脑电惊厥的作用较弱，行为惊厥与脑电惊厥有明确的分离现象．提示烟碱游离碱１．０ｍｇ·ｋｇ－１ｉｖ诱发行为惊厥与其激动中枢Ｎ受体有关．关键词烟碱；脑；受体，烟碱；惊厥     

烟碱及其重酒石酸盐诱发行为和脑电惊厥的特征

在清醒小鼠上，烟碱游离碱及其重酒石酸盐均可剂量依赖性地诱发行为和脑电?惊厥. 烟碱游离碱1.0 mg·kg^-1 iv在所有受试动物上均可诱发行为惊厥伴脑电癫痫样放电，并可被神经元型N受体拮抗剂美加明拮抗，但不被M受体拮抗剂阿托品和肌肉型N受体拮抗剂加拉碘铵所拮抗. 烟碱重酒石酸盐诱发行为?惊厥的作用较强，但诱发脑电惊厥的作用较弱，行为惊厥与脑电惊厥有明确的分离现象. 提示烟碱游离碱1.0 mg·kg^-1 iv诱发行为惊厥与其?激动中枢N受体有关.     

中枢N受体对M受体介导体温降低作用的调节

在清醒大鼠上，可进中枢的Ｎ受体拮抗剂美加明可对抗Ｎ受体激动剂烟碱降低体温的作用，增强Ｍ受体激动剂氧化震颤素降低体温的作用；不进中枢的外周Ｎ受体拮抗剂六甲溴铵不影响烟碱和氧化震颤素的上述作用．每天３次ｓｃ烟碱２．５ｍｇ·ｋｇ－１，连续７ｄ，大鼠对烟碱降低体温的作用产生慢性耐受后，氧化震颤素降低体温的作用无显著变化．提示以体温变化为指标，美加明封闭中枢Ｎ受体功能后，中枢Ｍ受体对其激动剂的敏感性增强；反复给予烟碱诱导中枢Ｎ受体功能失敏后，中枢Ｍ受体对其激动剂的敏感性无显著变化．     

大脑皮层~3H-三环哌酯结合位点的药理学特征

目的研究大脑皮层３Ｈ－三环哌酯（３Ｈ－ＴＣＰＮ）结合位点的药理学特征。方法在大鼠大脑皮层匀浆标本上，测定３Ｈ－ＴＣＰＮ的特异性结合位点以及药物对它的影响。结果３Ｈ－ＴＣＰＮ与大鼠大脑皮层膜标本具有特异性结合，其饱和性结合的参数与３Ｈ－ＱＮＢ的饱和性结合参数相似，其中，Ｋｄ值为０．４０ｎｍｏｌ·Ｌ－１，Ｂｍａｘ值为１２５８ｐｍｏｌ·ｇ－１。３Ｈ－ＴＣＰＮ特异性结合位点中，被阿托品取代的Ｍ受体部分占７０％，不被阿托品取代的称Ｘ位点部分占３０％；Ｘ结合位点既不为Ｎ受体激动剂烟碱和非竞争拮抗剂美加明所占据，也不为ＧＡＢＡ受体拮抗剂苦味毒素，甘氨酸受体拮抗剂士的宁和胆碱酯酶抑制剂毒扁豆碱所占据。结论大鼠大脑皮层３Ｈ－ＴＣＰＮ特异性结合位点中，７０％为Ｍ受体，其它位点的药理学性质有待进一步研究     

烟碱对M受体激动剂抑制自发活动的调节

间隔１０ｍｉｎ两次ｉｐ烟碱０．０２和０．２０ｍｇ·ｋｇ－１，小鼠对烟碱抑制自发活动的作用产生急性耐受，使Ｍ受体激动剂氧化震颤素５０μｇ·ｋｇ－１抑制自发活动的作用显著增强．间隔５ｍｉｎ两次ｉｐ烟碱０．２５和０．５０ｍｇ·ｋｇ－１，大鼠对烟碱抑制自发活动的作用产生急性耐受，使Ｍ受体激动剂槟榔碱５ｍｇ·ｋｇ－１抑制自发活动的作用也显著增强．提示反复注射烟碱诱导动物对烟碱急性耐受后，Ｍ受体激动剂抑制自发活动的作用显著增强．     

磷脂酰肌醇代谢对中枢烟碱受体功能的调节

目的：研究磷脂酰肌醇代谢中枢烟碱受体功能的调节作用，以分析脑烟碱受体与磷脂酰肌醇代谢之间的关系，方法：在小鼠上观察肌醇磷酸酶抑制剂氯化锂对烟碱诱发发惊厥作用的影响。结果：氯化锂２．５－１０ｍｍｏｌ．ｋｇ＾－１预处理后，烟碱诱发小鼠惊厥的量效关系发生变化，在高于半数效量的剂量下，烟碱诱发惊厥的作用显著增强，但氧颤莫林０．０５－０．２０ｍｇ．ｋｇ＾－１预处理后，烟碱诱发小鼠惊厥的量效关系无显著变化，在     

中枢烟碱受体亚型对小鼠被动回避行为的影响

目的：探讨中枢烟碱受体亚型在学习、记忆中的作用。方法：采用小鼠的被动回避反应法，观察四种不同选择性的烟碱受体（Ｎ受体）拮抗剂对学习和记忆行为的影响。结果：脑室注射ｋａｐｐａ－银环蛇毒（κ－ＢＴＸ）和六烃季铵（Ｃ６）明显抑制小鼠的学习和记忆行为的获得，且κ－银环蛇毒的作用有量—效关系；而α－银环蛇毒（α－ＢＴＸ）和双氢β－刺酮碱（ＤＨＢＥ）对小鼠的被动回避反应无明显影响。结论：中枢烟碱受体亚型在学习、记忆中起不同的作用，对κ－ＢＴＸ敏感的烟碱受体亚型可能在学习记忆中发挥重要作用。     

Modulation of phosphatidylinositol turnover on central nicotinic receptors

目的：研究磷脂酰肌醇代谢对中枢烟碱受体功能的调节作用，以分析脑烟碱受体与磷脂酰肌醇代谢之间的关系．方法：在小鼠上观察肌醇磷酸酶抑制剂氯化锂对烟碱诱发惊厥作用的影响．结果：氯化锂２５－１０ｍｍｏｌ·ｋｇ－１预处理后，烟碱诱发小鼠惊厥的量效关系发生变化，在高于半数效量的剂量下，烟碱诱发惊厥的作用显著增强．但氧颤莫林００５－０２０ｍｇ·ｋｇ－１预处理后，烟碱诱发小鼠惊厥的量效关系无显著变化．在小鼠上每日注射一次氯化锂５０ｍｍｏｌ·ｋｇ－１７ｄ后，烟碱诱发惊厥的作用显著减弱，半数效量由０５８增至０９７ｍｇ·ｋｇ－１．结论：磷脂酰肌醇代谢可调节中枢烟碱受体的功能．     

二苯羟乙酸奎宁酯对中枢烟碱受体功能的影响

二苯羟乙酸奎宁酯对中枢烟碱受体功能的影响汪海崔文玉刘传缋（军事医学科学院毒物药物研究所，北京１００８５０）二苯羟乙酸奎宁酯（ｑｕｉｎｕｃｌｉｄｉｎｙｌｂｅｎｚｉｌａｔｅ，ＱＮＢ）是经典的Ｍ受体拮抗剂，竞争性地与Ｍ受体呈高亲和力结合，在实验中一直作为研...     

Tolerance, cross-tolerance, and receptors after chronic nicotine or oxotremorine

Saline, 8.0 mg/kg/hr nicotine, or 1.0 mg/kg/hr oxotremorine was continuously infused into the jugular veins of DBA female mice. After 10 days of treatment, respiratory rate, Rotarod performance, Y-maze crossings, Y-maze rears, heart rate, and body temperature were measured after challenge with 2.0 mg/kg nicotine or saline or 0.2 mg/kg oxotremorine. Nicotine-infused mice were tolerant to the effects of nicotine for all six tests and oxtremorine-infused mice were tolerant to the effects of oxotremorine for all six tests and to the effects of nicotine on heart rate and body temperature. Oxotremorine infusion reduced the Bmax for [3H]-L-QNB binding, but had no effect on Bmax for either [3H]-DL-nicotine or [125I]-alpha-BTX binding. Conversely nicotine infusion did not alter the Bmax for [3H]-L-QNB binding, but increased the Bmax for both [3H]-DL-nicotine and [125I]-alpha-BTX binding. These results indicate that tolerance developed to the effects of two cholinergic agents, nicotine and oxotremorine, and that some cross-tolerance to the effects of nicotine occurred in oxotremorine-treated mice. Treatment with oxotremorine caused down-regulation of muscarinic receptors, while treatment with nicotine caused up-regulation of nicotinic receptors. Although some cross-tolerance to the effects of nicotine occurred in oxotremorine-treated mice, this did not appear to result from changes in nicotinic receptors.     

Activation of acetylcholine receptors and 5-HT2 receptors have additive effects in the suppression of neocortical high-voltage spindles in aged rats

We investigated if activation of the muscarinic or nicotinic acetylcholine receptors and serotonin (5-hydroxytryptamine; 5-HT) subtype 2 receptors would have additive or synergistic effects on the suppression of thalamocortically generated rhythmic neocortical high-voltage spindles (HVSs) in aged rats. The 5-HT₂ receptor antagonist, ketanserin, at a moderate dose (5 mg/kg) prevented the ability of a muscarinic acetylcholine receptor agonist, (oxotremorine 0.1 mg/kg), and a nicotinic acetylcholine receptor agonist (nicotine 0.1 mg/kg), to decrease HVSs. At a higher dose (20 mg/kg), ketanserin completely blocked the decrease in HVSs produced by moderate doses of muscarinic acetylcholine receptor agonists (pilocarpine 1 mg/kg and oxotremorine 0.1 mg/kg), and by a high dose of nicotine (0.3 mg/kg), though not that produced by high doses of pilocarpine (3 mg/kg) and oxotremorine (0.9 mg/kg). The ability of a 5-HT₂ receptor agonist, (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) (0.1–1.0 mg/kg), to suppress HVSs was non-significantly modulated by the nicotinic acetylcholine receptor antagonist, mecamylamine (1–15 mg/kg), and the muscarinic acetylcholine receptor antagonist, scopolamine (0.03–0.3 mg/kg). The effects of the drugs on behavioral activity could be separated from their effects on HVSs. The results suggest that activation of the muscarinic or nicotinic acetylcholine receptors plus 5-HT₂ receptors has additive effects in the suppression of thalamocortical oscillations in aged rats. Received: 2 November 1996 /Final version: 7 February 1997     

Differential effects of cholinergic drugs on discriminative cues and self-stimulation produced by electrical stimulation of the ventral tegmental area

Cholinergic receptors have been shown to modulate a subset of discriminative cues produced by electrical stimulation of the ventral tegmental area (VTA) in rats. The present study identified the specific cholinergic receptor type modulating these electrical brain-stimulation (EBS) cues, and assessed whether these receptors also mediated the rewarding effects of VTA EBS. The EBS cues were enhanced by the acetylcholinesterase inhibitor physostigmine and the muscarinic receptor agonists pilocarpine and RS-86, whereas the nicotinic receptor agonist nicotine had no effect. The enhancing effects of pilocarpine or RS-86 were attenuated by the muscarinic antagonist scopolamine. The EBS cues were not affected when scopolamine was injected alone, although high doses disrupted discriminated responses. Intracranial self-stimulation (ICSS) rates were depressed by physostigmine and pilocarpine and increased by nicotine and scopolamine. These results indicated a facilitatory influence of muscarinic receptors on the EBS cues, and an inhibitory role in VTA ICSS. Nicotinic receptor activation did not affect the EBS cues, but facilitated ICSS. These differential effects of cholinergic receptor activation point to a dissociation of the specific EBS cues measured in this study from the rewarding effects of VTA stimulation.     

Mediation of nicotine-induced convulsions by central nicotinic receptors of the 'C6' type

The nature of the central receptors mediating the convulsant actions of nicotine has been investigated. Clonic tonic convulsions were seen in mice following intracerebroventricular (i.c.v.) injection of nicotinic agonists. (-)Nicotine was the most potent agonist tested, with a CD50 of 7.9 X 10(-9) mol. (+)Nicotine, cytisine, DMPP and lobeline were 10-100 times less potent than (-)nicotine. Nicotine induced convulsions were antagonized by ganglion blocking drugs administered intraventricularly. Pentolinium was the most potent antagonist, with an ED50 of 4 X 10(-11) mol. The ganglion-blockers also produced convulsions in their own right at doses 80-1000 times the anti-nicotine ED50 dose. 'C10' blockers, such as d-tubocurarine, did not antagonize nicotine-convulsions, but produced convulsions in their own right. alpha-Bungarotoxin had neither convulsant nor anticonvulsant activity at the doses tested. It is concluded that the central receptors mediating this nicotinic effect resemble ganglionic ('C6') receptors, rather than neuromuscular ('C10') receptors.