In addition to their support role in neurotransmitter and ion buffering, astrocytes directly regulate neurotransmission at synapses via local bidirectional signaling with neurons. Here, we reveal a form of neuronal-astrocytic signaling that transmits retrograde dendritic signals to distal upstream neurons in order to activate recurrent synaptic circuits. Norepinephrine activates α1 adrenoreceptors in hypothalamic corticotropin-releasing hormone (CRH) neurons to stimulate dendritic release, which triggers an astrocytic calcium response and release of ATP; ATP stimulates action potentials in upstream glutamate and GABA neurons to activate recurrent excitatory and inhibitory synaptic circuits to the CRH neurons. Thus, norepinephrine activates a retrograde signaling mechanism in CRH neurons that engages astrocytes in order to extend dendritic volume transmission to reach distal presynaptic glutamate and GABA neurons, thereby amplifying volume transmission mediated by dendritic release.

中文翻译：

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星形胶质细胞放大去甲肾上腺素刺激的神经元树突体积传递。

除了在神经递质和离子缓冲中的支持作用外，星形胶质细胞还通过与神经元的局部双向信号传导直接调节突触中的神经传递。在这里，我们揭示了一种神经元-星形细胞信号传递的形式，该信号将逆行树突状信号传输至远端上游神经元，以激活复发性突触回路。去甲肾上腺素激活下丘脑促肾上腺皮质激素释放激素（CRH）神经元中的α1肾上腺素能受体，以刺激树突释放，从而引发星形细胞钙反应和ATP释放；ATP刺激上游谷氨酸和GABA神经元的动作电位，以激活CRH神经元的复发性兴奋性和抑制性突触回路。因此，