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。     

多巴胺D1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。     

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。     

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.     

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 ...     

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...     

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.     

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。     

跑台运动对攻击行为大鼠内侧下丘脑和中脑导水管周围灰质5-HT1A受体、5-HT2A受体蛋白表达的影响

目的:探讨跑台运动对攻击行为大鼠内侧下丘脑(MH)和中脑导水管周围灰质(PAG)5-HT1A受体、5-HT2A受体蛋白表达的影响,为研究运动对攻击行为改善的神经生物学机制提供实验基础.方法:3月龄雄性SD大鼠40只,体重160～180 g,随机分为4组:安静组(A)、攻击模型组(G)、攻击跑台组(GP)、入侵组(R)....     

5-HT1A受体阻断剂对乙醇引起大鼠低体温和行为性体温调节反应的影响

目的：观察5-羟色胺1A （5-HT_1A）受体阻断剂p-MPPI对乙醇引起大鼠低体温和行为性体温调节反应的影响。方法：用无线遥控测温技术记录成年雄性SD大鼠体核温度和活动的变化。用无线遥测温度梯度仪监测大鼠体核温度和行为性体温调节活动,将大鼠置于15℃~40℃的温度梯度箱内,并允许动物自由选择箱内温度,观察乙醇（3 g/kg）引起低体温和行为性体温调节的反应以及5-HT_1A受体阻断剂p-MPPI （1 mg/kg）对其效应的影响。结果：①乙醇能引起大鼠快速的体温降低反应,同时动物选择较低的环境温度。②5-HT_1A受体阻断剂p-MPPI能明显阻断乙醇引起的低体温和行为性体温调节变化。结论：①乙醇能使体温调定点降低,因为乙醇引起低体温时,大鼠选择较冷环境温度区;②5-HT可能参与乙醇引起低体温与行为性体温调节活动。     

Enantiomers of 11-hydroxy-10-methylaporphine having opposing pharmacological effects at 5-HT1A receptors

The two enantiomers of the title compound have been prepared by different synthetic routes. Both bind strongly to 5-HT1A receptors from rat forebrain membrane tissue. However, in a guinea pig ileum preparation, the (R)-enantiomer exhibits properties consistent with its being an agonist, whereas the (S)-enantiomer shows no agonist effect, but it blocks the actions of the (R)-enantiomer and of 8-hydroxy-2-di-n-propylaminotetralin (8-OH-DPAT), a 5-HT1A agonist. These data are presented as a rare example of enantiomers which demonstrate opposite pharmacological effects at the same receptor.     

CB1 knockout mice display impaired functionality of 5-HT1A and 5-HT2A/C receptors

Interaction between brain endocannabinoid (EC) and serotonin (5-HT) systems was investigated by examining 5-HT-dependent behavioral and biochemical responses in CB₁ receptor knockout mice. CB₁ knockout animals exhibited a significant reduction in the induction of head twitches and paw tremor by the 5-HT_2A/C receptor selective agonist (±) DOI, as well as a reduced hypothermic response following administration of the 5-HT_1A receptor agonist (±)-8-OH-DPAT. Additionally, exposure to the tail suspension test induced enhanced despair responses in CB₁ knockout mice. However, the tricyclic antidepressant imipramine and the 5-HT selective reuptake inhibitor fluoxetine induced similar decreases in the time of immobility in the tail suspension test in CB₁ receptor knockout and wild-type mice. No differences were found between both genotypes with regard to 5-HT_2A receptor and 5-HT_1A receptors levels, measured by autoradiography in different brain areas. However, a significant decrease in the ability of both, the 5-HT_1A receptor agonist (±)-8-OH-DPAT and the 5-HT_2A/C receptor agonist (−)DOI, to stimulate [³⁵S]GTPγS binding was detected in the hippocampal CA₁ area and fronto-parietal cortex of CB₁ receptor knockout mice, respectively. This study provides evidence that CB₁ receptors are involved in the regulation of serotonergic responses mediated by 5-HT_2A/C and 5-HT_1A receptors, and suggests that a reduced coupling of 5-HT_1A and 5-HT_2A receptors to G proteins might be involved in these effects.     

The Influence of Gender and Age on Neonatal Rat Hypothalamic 5-HT1A and 5-HT2A Receptors

1.Rat hypothalamic 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) concentrations are transiently sexually differentiated in the second week postpartum (pp), with higher levels in the female. In this report we investigate the possibility that 5-HT receptors may also exhibit sexual dimorphism in the neonatal period.2.5-HT1A and 5-HT2A receptors were quantitated by radioligand binding of [³H]ketanserin and [³H]8-OH DPAT, respectively, in hypothalamus and amygdala from male and female rats at days 8–16 pp.3.There was no sexual dimorphism or change in the density of 5-HT2A binding in hypothalamus or amygdala over days 8–16 pp. There was also no sexual dimorphism of 5-HT1A receptors.4.There was an increase in 5-HT1A receptor density in both the hypothalamus and the amygdala. In the hypothalamus, but not the amygdala, this increase was interrupted on day 14 by a decrease in 5-HT1A receptors, which we suggest may be of physiological significance in modifying the eventual pattern of adult agonistic activity.5.The results suggest that the sexual dimorphism in 5-HT turnover is predominantly presynaptic, relating to altered synthesis and/or release, and is not of sufficient magnitude or duration to produce adaptive responses in postsynaptic 5-HT1A or 5-HT2A receptors.     

Identification and role of serotonin 5-HT1A and 5-HT1B receptors in primary cultures of rat embryonic rostral raphe nucleus neurons

Autoregulatory mechanisms affecting serotonin [5-hydroxytryptamine (5-HT)] release and synthesis during the early period of development were investigated in dissociated cell cultures raised from embryonic rostral rat rhombencephalon. The presence of 5-HT1A and 5-HT1B receptors in serotoninergic neurons was assessed using binding assays. The involvement of 5-HT1A and 5-HT1B receptors in the control of the synthesis and release of [3H]5-HT was studied using biochemical approaches with several serotoninergic receptor ligands. A mean decrease of 30% in [3H]5-HT synthesis and release was observed in the presence of 5-HT (10(-8) M), the 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), the 5HT1B/1A agonist 5-methoxy-3-(1,2,5,6-tetrahydro-4-pyridinyl)-1H-indole (RU 24969), the 5-HT1B agonist 3-(1,2,5,6-tetrahydropyrid-4-yl)pyrrolo[3,2-b]pyrid-5-one (CP-93,129), and the 5-HT(1D/1B) agonist sumatriptan. Inhibition of 5-HT synthesis and release induced by 8-OH-DPAT was blocked by chiral N-tert-butyl-3-[1-[1-(2-methoxy)phenyl]piperazinyl]-1-phenylpropionam ide dihydrochloride quaternary-hydrate (WAY 100135) (10(7) M) or methyl 4-[4-[4-(1,1,3-trioxo-2H-1,2-benzoisothiazol-2-yl)butyl]-1-p iperazinyl]-1Hindole-2-carboxylate (SDZ 216-525) (10(-7)M), and that of CP-93,129 was blocked by methiothepin (10(-7) M). Paradoxically, extracellular levels of [3H]5-HT increased in the presence of 8-OH-DPAT and RU 24969 at 10(-6) M. 5-HT uptake experiments showed that these two agonists interacted with the 5-HT transporter. 5-HT1 binding sites (620 fmol/mg of protein) and 5-HT1A (482 fmol/mg of protein) and 5-HT1B (127 fmol/mg of protein) receptors were detected in 12-day in vitro cell cultures. Experiments carried out with tetrodotoxin suggested that 5-HT1A receptors are located on nerve cell bodies, whereas 5-HT1B receptors are located on the nerve terminals. We concluded that autoregulatory mechanisms involving 5-HT1A and 5-HT1B autoreceptors are functionally mature in cells from rostral raphe nuclei during the early period of development.     

Activation of 5-HT(1A) but not 5-HT(1B) receptors attenuates an increase in extracellular dopamine derived from exogenously administered L-DOPA in the striatum with nigrostriatal denervation

In order to determine whether L-DOPA-derived extracellular dopamine (DA) in the striatum with dopaminergic denervation is affected by activation of serotonin autoreceptors (5-HT(1A) and 5-HT(1B) receptors), we applied in vivo brain microdialysis technique to 6-hydroxydopamine-lesioned rats and examined the effects of the selective 5-HT(1A) receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and the selective 5-HT(1B) receptor agonist CGS-12066 A on L-DOPA-derived extracellular DA levels. Single L-DOPA injection (50 mg/kg i.p.) caused a rapid increase and a following decrease of extracellular DA, with a peak value at 100 min after L-DOPA injection. Pretreatment with both 0.3 mg/kg and 1 mg/kg 8-OH-DPAT (i.p.) significantly attenuated an increase in L-DOPA-derived extracellular DA and the times of peak DA levels were prolonged to 150 min and 225 min after L-DOPA injection, respectively. These 8-OH-DPAT-induced changes in L-DOPA-derived extracellular DA were antagonized by further pretreatment with WAY-100635, a selective 5-HT(1A) antagonist. In contrast, intrastriatal perfusion with the 5-HT(1B) agonist CGS-12066 A (10 nM and 100 nM) did not induce any changes in L-DOPA-derived extracellular DA. Thus, stimulation of 5-HT(1A) but not 5-HT(1B) receptors attenuated an increase in extracellular DA derived from exogenous L-DOPA. These results support the hypothesis that serotonergic neurons are primarily responsible for the storage and release of DA derived from exogenous L-DOPA in the absence of dopaminergic neurons.