精氨酸加压素调制PO/AH温度敏感神经元突触传递的机制

Arginine vasopressin (AVP), an important neurotransimitter or modulator in central nervous system, is involved in anti-febrile and physiological thermoregulation .Our previous researches have demonstrated that AVP, acting V1a receptor (G protein coupled receptor),excites warm-sensitive neurons and inhibits cold-sensitive neurons in preoptic anterior hypothalamus (PO/AH). While according to previous reports, the acitvity of temperature-sensitive neuron in PO/AH was modulated by synaptic transmission. In preliminary experiment, we found that AVP reduced the amplitude and frequency of IPSCs (Inhibitory postsynaptic currents) of warm-sensitive neurons in PO/AH by V1a receptor, but the mechanism of effect is still unknown. On that basis, in this project we will investigate the co-express of V1a receptor and NMDA, AMPA, GABAA receptor in PO/AH temperature-sensitive neurons, the mechanisms of AVP modulated on currents induced by NMDA, AMPA or GABAA receptor in PO/AH temperature-sensitive neurons and elucidate the modulation mechanism is that the PLC-IP3/Ca2+ and DG/PKC signal pathway is activated by V1a receptor by immunofluorescence histochemistry, patch clamp and ion imaging technology, neuropharmacology, molecular biology and behavior methods. This research not only helps to further clarify the mechanism of AVP affecting the activity of temperature-sensitive neurons in PO/AH by the point of view of synaptic transmission, but also it is very important for further understanding of AVP how to play a role in anti-febrile and physiological thermoregulation.

精氨酸加压素（AVP）是一种重要的中枢神经递质或调质，参与退热与正常体温调节。我们前期工作证实，AVP通过V1a受体（G蛋白偶联受体）兴奋PO/AH热敏神经元，抑制冷敏神经元，而有报道PO/AH温敏神经元的活动又受到突触传入的调制。我们预实验发现AVP通过V1a受体减少热敏神经元抑制性突触后电流幅度和频率，但机制尚未阐明。在此基础上，本项目将采用免疫荧光组化、膜片钳与离子成像技术、神经药理学和分子生物学方法，从脑片、细胞水平，观察PO/AH温敏神经元V1a受体与NMDA、AMPA或GABAA受体的共表达；研究AVP调制温敏神经元NMDA、AMPA和GABAA受体介导电流的机制，阐明调制机制是V1a受体激活PLC-IP3/Ca2+和DG/PKC信号通路。本研究不仅可从突触传递角度，进一步阐明AVP影响PO/AH温敏神经元活动的机制，而且对深入了解AVP如何参与退热与正常体温调节具有重要意义。

下丘脑视前区（POA）分布有温度敏感和不敏感神经元，在机体自主性体温调节中发挥了关键作用。精氨酸加压素（AVP）是一种重要的中枢神经递质或调质，通过增加POA热敏神经元的放电活动，抑制冷敏神经元和温度不敏感神经元从而引起低温反应。POA神经元的活动又受到突触传入的调制作用。本项目通过免疫荧光、膜片钳技术、药理学和分子生物学方法证实POA存在AVP V1a受体、NMDA受体（NR2A，NR2B，NR1）、AMPA受体（GluR1，GluR2，GluR3）和GABAA受体（α1，α2，α3，β2， β3，γ2）亚型或亚单位的表达。AVP差异性地调制POA温度敏感和不敏感神经元GABA能突触传递。AVP抑制POA温度敏感和部分温度不敏感神经元的sIPSC，易化部分温度不敏感神经元的sIPSC。这种AVP对温度敏感和不敏感神经元sIPSC的差异性调制作用可能与PKC、CaMKII磷酸化GABAA受体，改变通道动力学有关，而不依赖于GABAA受体基因表达的变化。AVP V1a受体激活PKC、CaMKII调节NMDA受体（NR2A，NR2B，NR1）、AMPA受体（GluR1，GluR2，GluR3）的表达和磷酸化。这些实验结果，基本证实了提出的假说：AVP通过V1a受体激活PLC-IP3/Ca2+和DG/PKC信号通路，调节POA温度敏感神经元NMDA、AMPA和GABAA受体活动，调制突触传递。探讨AVP V1a受体信号通路激活与突触电流变化的内在联系，有利于阐明AVP调制POA温度敏感神经元突触传递的机制。本项目假说的验证，可为AVP影响POA温度敏感神经元活动的作用机制提供新的实验及理论证据，而且对进一步揭示AVP如何参与退热与正常体温调节具有重要意义。