多巴胺D_1受体参与新生鼠离体延髓脑片呼吸节律性放电的调节

本研究旨在探讨多巴胺D1受体在延髓离体脑片基本节律性呼吸放电调节中的作用。以改良的Kreb’s液（modified Kreb’s perfusion,MKS）恒温灌流Sprague—Dawley大鼠（0～3d）离体延髓脑片标本,稳定记录到与之相连的舌下神经根的呼吸节律性放电活动（respiratory rhythmical discharge activity,RRDA）后,第一组（n=5）先给予多巴胺D1受体特异性激动剂[cis-（±）-1-（Aminomethyl）-3,4-dihydro-3-phenyl-1H-2-Benzopyran-5,6-Diolhy,drochlo—ride,A68930]灌流10min,用MKS洗脱后,再给予多巴胺D1受体特异性拈抗剂[R（＋）-7-Chloro-8-hydroxy-3-methyl—1—pheny1-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride,SCH-23390]灌流10min;第二组（n=5）先给予A68930持续灌流10min后再给予A68930＋SCH-23390持续灌流10min;观察各时间点舌下神经根RRDA的变化。结果显示,给予A68930灌流后呼吸周期（respiratory cycle,RC）和呼气时程（expiratory time,TE）显著缩短,放电积分幅度（integral amplitude,IA）增加,吸气时程（inspiratory time,TI）无明显变化;给予SCH-23390后RC、TE显著延长、TI显著缩短、IA减小,而且A68930的作用可以被SCH．23390部分逆转。这些观察结果提示多巴胺D1受体参与了哺乳动物基本呼吸频率和幅度的调节。     

5-HT2A受体在尼可刹米增强新生大鼠延髓脑片呼吸放电中的作用

本文旨在探讨中枢呼吸兴奋剂尼可刹米对新生大鼠基本节律性呼吸的产生和调节的影响及5-HT2A受体在其中的作用.制作新生大鼠离体延髓脑片标本,含面神经后核内侧区(the medial region of the nucleus retrofacialis,mNRF)并保留舌下神经根,灌流改良Kreb'S液(modified Kreb'S solution,MKS),记录舌下神经根呼吸相关节律性放电活动(respiratory-re-lated rhythmic discharge activity,RRDA),观察不同浓度尼可刹米、5-HT2A受体特异激动剂2,5-二甲氧基-4-碘苯基丙烷[1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane,DOI]、5-HT2A受体特异拮抗剂酮舍林(ketanserine)以及联合使用尼可刹米和酮舍林对舌下神经根RRDA的影响.结果显示,尼可刹米在0.5～7μg/mL时对延髓脑片RRDA有兴奋作用,在5 μg/mL时对吸气时程(inspiratory time,TI)、放电积分幅度(integral amplitude,IA)、呼吸周期(respiratory cycle,Re)等呼吸指标综合效果最显著.DOI明显延长TI、增强IA、缩短RC,对RRDA有兴奋作用.酮舍林明显缩短TI、减弱IA、延长RC,对RRDA有抑制作用.联合使用DOI和酮舍林对RRDA无明显作用.酮舍林可完全阻断尼可刹米对RC的作用,部分阻断尼可刹米对IA的作用,对尼可刹米引起的TI变化无明显影响.结果提示,尼可刹米增强新生大鼠离体延髓脑片舌下神经根RRDA,5-HT2A受体可能足尼可刹米作用途径之一.     

组胺H1和H2受体在新生大鼠离体延髓脑片呼吸节律性放电调节中的作用

本研究探讨组胺H1和H2受体在新生大鼠基本节律性呼吸的发生和调节中的作用.以改良的Kreb's液恒温灌流新生Sprague-Dawley大鼠离体延髓脑片标本,稳定记录与之相连舌下神经根的呼吸节律性放电活动(respiratory-related rhythmical discharge activity, RRDA).实验分为5组:第1、2、3组分别单独给予组胺(histamine, HA)、 H1受体特异阻断剂pyrilamine和H2受体特异阻断剂cimetidine;第4组分别先后给予HA和HA pyrilamine;第5组分别先后给予HA和HA cimetidine,观察舌下神经根RRDA的变化.结果显示,单独给予HA后呼吸周期(respiratory cycle, RC)及呼气时程(expiratory time, TE)明显缩短,而吸气时程(inspiratory time, TI)及放电积分幅度(integral amplitude, IA)无明显变化;给予pyrilamine后RC、 TE明显延长,TI、 IA也无明显变化,且HA的作用可以被pyrilamine逆转;给予cimetidine后RC、 TE、 TI、 IA均无明显变化,且HA的作用不能被cimetidine逆转.结果提示,H1受体参与哺乳动物基本呼吸节律的产生和调节,H2受体对哺乳动物基本节律性呼吸的调控无明显影响.     

NMDA与非NMDA受体激动剂对新生大鼠延髓脑片呼吸节律性放电的作用

目的：探讨N－甲基－D－天门冬氨酸（NMDA）和非NMDA类受体在基本呼吸节律发生和调节中的可能作用。方法：以改良的Kerb's液灌流新生SD大鼠离体延髓脑片,记录片与之相连的舌下神经的呼吸节律性放电活动（respiratory rhythmical discharge activity,RRDA),在灌流中给予兴奋性氨式酸类递质及相应的拮抗剂,观察其对RRDA的影响。结果：使用非NMDA受体激动剂海人酸（KA）后,可见呼吸周期及呼吸时间有所延长,NMDA受体激动剂NMDA对呼吸活动则没有明显影响;相应的拮抗剂6－氰基－7－硝基喹恶啉土卫四（DNAX）和2－氨基酸戊酸（AP5）均可使放电频率和积分幅值明显降低,吸气时间显著缩短,但DNQX同时可致呼吸周期和呼气时间明显缩短。结论：在哺乳动物基本呼吸节律的产生和调节中,NMDA类受体主要对呼吸活动的强度产生调节作用;而非NMDA类受体不仅可以影响呼吸的强度,同时对呼吸的频率也发挥调节作用。     

腺苷A1受体在离体延髓脑片上对节律性呼吸的调制

实验旨在探讨腺苷A1受体在对基本呼吸节律调制中的可能作用。制作新生大鼠离体延髓脑片标本,主要包含面神经后核内侧区(themedial region of the nucleus retrofacialis,mNRF),并保留完整的舌下神经根。以改良Kreb‘s液灌流脑片,记录mNRF吸气神经元的电活动,并同步记录舌下神经根呼吸节律性放电(respiratory rhythmical discharge activity,RRDA)。在灌流液中先分别单独给予腺苷A1受体的特异性拮抗剂8-环戊-1,3-二丙基黄嘌呤(8-cyclopenty 1-1,3-dipropylxanthine,DPCPX)和特异性激动剂R-苯异丙基-腺苷(R-phenylisopropyl-adenosine,R-PIA);再分别先后给予R-PIA和R-PIA DPCPX,观察RRDA和吸气神经元电活动的变化。结果显示,给予腺苷A1受体拮抗剂DPCPX后,呼气时程和呼吸周期明显缩短,吸气神经元中期放电的频率和峰频率显著增大;给予腺苷Al受体激动剂R-PIA后,吸气时程、积分幅度和吸气神经元中期放电的频率和峰频率均显著降低,呼吸周期明显延长,且R-PIA的呼吸抑制作用可部分地被DPCPX逆转。实验结果提示,腺苷A1受体可能通过介导吸气神经元的抑制性突触输入参与节律性呼吸的调制。     

cAMP-PKA通路参与Ⅱ组代谢性谷氨酸受体对新生鼠离体延髓脑片呼吸节律性放电的调节

本研究旨在探讨cAMP-PKA通路在Ⅱ组代谢性谷氨酸受体对离体延髓脑片呼吸节律性放电的影响中的作用。制作新生大鼠离体延髓脑片标本,主要包含延髓面神经后核内侧区(medial region of the nucleus retrofacialis,mNRF),并完整保留舌下神经根,以改良Kreb’s液(modified Kreb’s solution,MKS)恒温灌流脑片,用吸附电极记录舌下神经根呼吸节律性放电活动(respiratory rhythmical discharge activity,RRDA)。待放电活动稳定后,第1组灌流Ⅱ组代谢性谷氨酸受体特异性拮抗剂(2S)-α-ethylglutamic acid(EGLU)10min,第2组先给予cAMP-PKA通路激动剂Forskolin灌流10min,而后MKS洗脱至正常,灌流cAMP-PKA通路抑制剂Rp-cyclic3’,5’-hydrogen phosphorothioate adenosine triethylammonium salt(Rp-cAMPS)10min,第3组首先给予Rp-cAMPS10min,洗脱后联合Rp-cAMPS+EGL...     

一氧化氮对呼吸节律性放电的调节作用

实验旨在探讨一氧化氮(nitric oxide,NO)在基本呼吸节律产生和调节中可能的作用。制作新生大鼠离体延髓脑片标本,主要包含面神经后核内侧区,前包钦格复合体、腹侧呼吸组以及背侧呼吸组的一部分。同时保留舌下神经根,用改良Kreb′s液灌流脑片并记录与之相连的舌下神经根呼吸节律性放电(respiratory rhythmical discharge activity,RRDA),在灌流液中分别给予不同浓度的NO供体硝普钠(sodium nitroprusside,SNP),NO合成前体L—精氨酸(L—Arginine,L-Arg)以及神经元型一氧化氮合酶(neuronal nitric oxide synthase,nNOS)特异性抑制剂7-nitro indazole (7-NI),观察其对RRDA的影响。结果显示,nNOS的特异性抑制剂7-NI对吸气时程和放电强度有明显抑制,而NO合成前体L—Arg,以及NO供体SNP对呼吸放电活动没有明显的影响。这提示,在哺乳动物基本呼吸节律的产生和调节中,NO可能对吸气中止和呼吸幅度具有调节作用。     

切割延髓、酸碱度及温度对新生大鼠离体延髓—脊髓标本呼吸节律性放电的影响

目的和方法：在新生大鼠离体延髓－－脊髓标本上,用吸附电极记录膈神经根－颈4、颈5腹根（C4v,C5v)和舌下神经根（Ⅻ）节律性放电活动(rhythmical discharge activity,RDA),并观察其在对延髓微切割、改变灌流液pH值及温度后RDA的变化。结果：①新生鼠离体延髓－脊髓标本在这灌流条件下,可存活6－8h,持续4h可稳定记录到C4v、C5v和Ⅻ的RDA,且两者完全同步,为呼吸节律性放电（RDA,RRDA）;②从延髓头端向尾端切割（每次100μm）,切至闩前500μm水平时,RRDA不变,进一步切割,至闩水平,RRDA消失;③从尾端向头端切割,切至舌下神经根下缘水平,RRDA不变,进一步向头端切割,RRDA逐渐消失;④从延髓背侧向腹侧水平切割,切割至背→腹一半水平时,RRDA不变,进一步向腹侧切割,RRDA逐渐消失;⑤灌流液的pH值从7.35降至6.85,RRDA逐渐增强,而从6.85降至4.5时,逐渐减弱至消失。pH值从7.45上升到7.85,呼吸频率逐渐减漫,放电幅度增强;⑥温度由27℃上升到37℃,RRDA逐渐增强;由38℃上升到41℃,RRDA逐渐减弱,温度则27℃降23℃,RRDA逐渐减弱。温度为42℃或22℃时,RRDA消失。结论：面神经后核内侧区可能是呼吸节律起源的部位,且此区域的神经元对温度及酸碱度变化敏感。     

内源性一氧化碳参与呼吸节律调节

本文旨在探讨内源性一氧化碳（carbon monoxide,CO）对呼吸节律的调节作用。采用新生Sprague—Dawley大鼠,制备离体延髓脑片标本,分别灌流CO、血红素氧合酶（heme oxygenase,HO）底物高铁血红素（hemin）和HO抑制剂ZnPP-9,观察舌下神经根呼吸样传出放电节律的变化。实验分为5组：单纯人工脑脊液（artificial cerebrospinal fluid,ACSF）对照组、ZnPP-9组、外源性CO组、Hemin组和ZnPP-9＋Hemin组。结果如下：在ZnPP-9组,舌下神经根节律性放电频率（discharge frequency,DF）增快（P〈0．05）;在外源性CO组,舌下神经根节律性DF减慢（P〈0.05）;在Hemin组和ZnPP-9＋Hemin组,舌下神经根节律性DF增快（P〈0．05）。结果表明,内源性CO对呼吸节律可能具有调节作用。     

8-OH-DPAT对大鼠体感皮质5-羟色胺抑制单位自发放电的抑制作用

目的：研究5-羟色胺（5-HT）对大鼠大脑皮质第一体表感觉区自发单位放电（SI-SUD）的影响,以及5-HT1A受体在5-HT抑制SI-SUD中的可能作用。方法：记录微电泳5-HT及5-HT1A受体选择性激动剂8-OHDPAT前后的SISUD,分析：MISISUD的平均放电间隔（MISI）变化并作统计学处理。结果：①微电泳5-HT对SISUD的影响有3种情况：则MISI增大（抑制作用）（48／96）;MISI减小（兴奋作用）（26／96）或MISI无明显改变（无明显影响）（22／96）。其中以抑制作用为主。②在20个5-HT押制单位中,微电泳8-OH-DPAT可抑制其中17个单位的SISUD,而其余3个单位的SISUD无明显改变。结论：5-HT对SISUD的影响以抑制作用为主。体感皮质的大部分5-HT抑制单位存在有5-HT1A受体,并参与5-HT对SI-SUD的抑制作用。     

cAMP-PKA通路参与Ⅱ组代谢性谷氨酸受体对新生鼠离体延髓脑片呼吸节律性放电的调节

本研究旨在探讨cAMP-PKA通路在Ⅱ组代谢性谷氨酸受体对离体延髓脑片呼吸节律性放电的影响中的作用.制作新生大鼠离体延髓脑片标本,主要包含延髓面神经后核内侧区(medial region of the nucleus retrofacialis,mNRF),并完整保留舌下神经根,以改良Kreb's液(modified ...     

Glial Cells are Involved in the Exciting Effects of Doxapram on Brainstem Slices In Vitro

This study tested whether the glial cells are involved in the exciting effects of doxapram on brainstem slice in vitro. Experiments were performed in brainstem slice preparations from neonatal rats. The medial area of nucleus retrofacialis (mNRF) and the hypoglossal nerve (XII nerve) were contained in the preparations. The slices were perfused with modified Kreb’s solution (MKS), and the rhythmical respiratory discharge activity (RRDA) was simultaneously recorded from the XII nerve by using suction electrodes, including the discharge time course of inspiratory (Ti), expiratory (Te), respiratory cycle (RC), and integrity amplitude of inspiratory discharge (IA). After applying of doxapram (5 μM) to the MKS for 10 min, Ti and IA increased significantly (85.0 ± 25.0%, 13.2 ± 2.5%, respectively, P < 0.05), the Te and the RC decreased significantly (19.0 ± 1.4%, 12.8 ± 1.4%, respectively, P < 0.05) when compared with control group. When the methionine sulfoximine (MS, 10 μM), a blockage of glutamine synthetase, was applied, all the exciting effects of doxapram on RRDA were reversed. After the glutamine (20 μM) was applied to the MKS for 10 min, the exciting effects were revealed again. Our results suggest that the normal metabolism of glial cells takes a key role in the modification of the RRDA in the slices. In conclusion, glial cells are involved in the exciting effects of doxapram on brainstem slice in vitro.     

Raphe modulation of the pre-Bötzinger complex respiratory bursts in in vitro medullary half-slice preparations of neonatal mice

Spontaneous respiratory bursts which begin in the pre-Bötzinger complex were recorded from the hypoglossal (XIIth) nerve rootlets of in vitro slices prepared from newborn mice. First, we examined the respiratory bursts before and after a midline or para-midline transection which spared the caudal raphe nuclei: the raphe obscurus and raphe pallidus. After a midline transection, the respiratory bursts in both half-slices were desynchronized and had slightly decreased amplitudes and frequencies. After a para-midline transection, the bursts continued with similar frequencies in the half slice containing the raphe obscurus and raphe pallidus. Second, to analyze the effects of modulation by the raphe obscurus and raphe pallidus, a dorsal or ventral midline lesion was used to damage either the raphe obscurus or raphe pallidus. After a dorsal lesion, the synchronized respiratory bursts persisted with slightly decreased frequencies. In contrast, after a ventral lesion, the bursts were almost completely abolished, but recovered significantly after the addition of 5-HT. The present results demonstrated that the pre-Bötzinger complex on each side of the medulla can independently generate rhythmic respiratory activity. It is suggested that the 5-HT released from the ventral part of the raphe nuclei (predominantly the raphe pallidus) plays a critical role in sustaining rhythmic respiratory bursts.     

Thyroliberin and its analog lacking hormonal properties stimulate respiratory center activity in the frog Rana temporaria

It has been shown that thyroliberin and its synthetic analogue PR-546 injected into the lymphatic sacs (4.10(-7)-4.10(-9) g/kg) or applied to the medulla oblongata in the bulbar frogs (4.10(-10)-4.10(-12) g/kg) significantly increase the rate of motor respiratory volleys in the hypoglossal nerve. In preparations with the irregular level of the activity of the respiratory center, these drugs enhanced stabilization of the initial level of the rhythm of motor respiratory discharges.     

Role of serotonergic input to the ventrolateral medulla in expression of the 10-Hz sympathetic nerve rhythm

We studied the changes in inferior cardiac sympathetic nerve discharge (SND) produced by unilateral microinjections of 5-hydroxytryptamine (5-HT) receptor agonists and antagonists into the ventrolateral medulla (VLM) of urethane-anesthetized, baroreceptor-denervated cats. Microinjection of the 5-HT2 receptor antagonist LY-53857 (10 mM) into either the rostral or caudal VLM significantly reduced (P < or = 0.05) the 10-Hz rhythmic component of basal SND without affecting its lower-frequency, aperiodic component. The selective depression of 10-Hz power was accompanied by a statistically significant decrease in mean arterial pressure (MAP). Microinjection of LY-53857 into the VLM also attenuated the increase in 10-Hz power that followed tetanic stimulation of depressor sites in the caudal medullary raphé nuclei. Microinjection of the 5-HT2 receptor agonist 1-(2,5-dimethoxy-4-iodophenyl)2-amino-propane (DOI; 10 microM) into the VLM selectively enhanced 10-Hz SND, and intravenous DOI (1 mg/kg) partially reversed the reduction in 10-Hz SND produced by 5-HT2 receptor blockade in the VLM. Microinjection of the 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OHDPAT; 10 mM), into either the rostral or caudal VLM also selectively attenuated 10-Hz SND and significantly reduced MAP. The reduction in 10-Hz SND produced by 8-OHDPAT was partially reversed by intravenous WAY-100635 (1 mg/kg), which selectively blocks 5-HT1A receptors. These results support the view that serotonergic inputs to the VLM play an important role in expression of the 10-Hz rhythm in SND.