Mechanism of the transmitter release facilitation through activation of presynaptic ATP receptors in the brainstem

通过激活脑干突触前 ATP 受体促进递质释放的机制

• 批准号: 13680902
• 负责人: KATO Fusao
• 金额: $ 1.98万
• 依托单位: Jikei University School of Medicine
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13680902/
• 关键词: nucleus tractus solitarii; brain slice; patch-clamp; postsynaptic current; adenosine 5 ' -triphosphate; P2X receptor; glutamate release; presynaptic ligand-gated channels

P2X receptors (P2X-Rs) are ATP-gated channels permeable to cations inclining Ca^<2+>. We recorded miniature excitatory postsynaptic currents (mEPSCs) under blockade of voltage-dependent Na^+ channels from second-order neurons in the nucleus tractus solitarii in vitro, a part of the brain where exogenous ATP has profound effects on autonomic outflow. Activation of presynaptic P2X-Rs with ATP or α,β-methylene ATP (α,βmATP) not only enhanced the release of glutamate, but could initiate it de novo even when voltage-dependent calcium channels (VDCCs) were completely blocked. This facilitating effect of αβmATP on the glutamate release was abolished completely by a P2X-R antagonist pyridoxalphosphate-6-azophenyl-2',4' -disulphonic acid (PPADS) and by a high, but not a low, concentration of a subtype-selective antagonist 2 > ,3 ' -O-(2,4,6-trinitrophenyl)-ATP (TNP-ATP). Despite manifest increase in the frequency of excitatory postsynaptic events by αβmATP, the rate of the synaptic failures as evaluated by solitary tract stimulation was not significantly affected. The miniature excitatory postsynaptic potentials elicited with P2X-R agonists recorded under blockade of VDCC-dependent synaptic transmission were sufficient to trigger action potentials in the postsynaptic cell. These results show that a rise in extracellular ATP concentration promotes excitatory transmission even in the absence of presynaptic excitation, leading to a consequent activation of the autonomic networks.

P_2X受体(P_2X-R)是一种ATP门控通道，可被钙离子通透。我们在体外记录了孤束核二级神经元电压依赖性钠通道阻断下的微型兴奋性突触后电流(MEPSCs)，这是大脑中外源性ATP对自主神经流出有深刻影响的部分。用三磷酸腺苷或α，β-亚甲基三磷酸腺苷(α，β-mATP)激活突触前P2X-R不仅能增加谷氨酸的释放，而且在电压依赖性钙通道(VDCC)完全阻断的情况下也能重新启动谷氨酸的释放。这种促进谷氨酸释放的作用可被P2X-R拮抗剂吡哆醇磷酸-6-偶氮苯基-2‘，4’-二磺酸(PPADS)和亚型选择性拮抗剂2，3‘-O-(2，4，6-三硝基苯基)-αβ(2，4，6-三硝基苯基)-三磷酸腺苷(TNPATP)完全阻断。尽管αβ-mATP能明显增加兴奋性突触后事件的发生频率，但对孤束刺激所评估的突触失败率没有明显影响。在阻断VDCC依赖的突触传递的情况下，用P2X-R激动剂记录到的微小兴奋性突触后电位足以触发突触后细胞的动作电位。这些结果表明，即使在没有突触前兴奋的情况下，细胞外ATP浓度的升高也促进了兴奋性传递，从而导致自主神经网络的激活。

项目成果

Nishi H, Kato F, Masaki E, Kawamura M: "ADP-sensitive purinoceptors induce steroidogenesis via adenylyl cyclase activation in bovine adrenocortical fasciculata cells"Brit J Pharraacol. J137. 177-184 (2002)

Nishi H、Kato F、Masaki E、Kawamura M：“ADP 敏感嘌呤受体通过牛肾上腺皮质束状细胞中的腺苷酸环化酶激活诱导类固醇生成”Brit J Pharraacol。

Kawamura M, Masaki E, Kato F: "Regulation of inhibitory synaptic transmission by cholinoceptors in the brainstem nociceptive network of the rat"The 3rd International Symposium on the Study of Brain Function Abstracts. 213 (2002)

Kawamura M、Masaki E、Kato F：“大鼠脑干伤害性网络中胆碱受体对抑制性突触传递的调节”第三届国际脑功能研究研讨会摘要。

Kawamura M, Tanaka J. Inoue K, Kato F: "Rat kaiba CA3 suitai saibou heno kohunsei oyobi yokuseisei shinapusu nyuuryoku ni oyobosu saibougai ATP no souhantekisayou (in Japanese)"Shinkei-Kagaku. 40 (2&3). 437 (2001)

Kawamura M、Tanaka J. Inoue K、Kato F：“Rat kaiba CA3suitai saibou heno kohunsei oyobi yokuseisei shinapusu nyuuryoku ni oyobosu saibougai ATP no souhantekisayou（日语）”Shinkei-Kagaku。

Kato F: "Kosokukaku ATP-juyotai to kokyuseigyo (in Japanese)"Kokyu-to-Junkan. 50. 43-51 (2002)

加藤 F：“Kosokukaku ATP-juyotai to kokyuseigyo（日语）”Kokyu-to-Junkan。

Kato F: ""Hitotsubu de nido oishi" saibou-gai messenger to shiteno ATP - Saibou-gai ATP to purine juyotai niyoru nounai shiiiapusu dentatsu no taju-seigyo (in Japanese)"No-kinou No Kaimei - Seimei Kagaku no Syuchoryuu- eds.Akaike, Higashi, Abe, Kubo.Gaiya

加藤 F：““Hitotsubu de nido oishi”saibou-gai Messenger tooshiten ATP - Saibou-gai ATP to purine juyotai niyoru nounai shiiiapusu dentatsu no taju-seigyo（日文）”No-kinou No Kaimei - Seimei Kagaku no Syuchoryuu-eds