Stagkourakis Stefanos, Kim Hoseok, Lyons David J, Broberger Christian
Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden.
Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden.
Cell Rep. 2016 Apr 26;15(4):735-747. doi: 10.1016/j.celrep.2016.03.062. Epub 2016 Apr 14.
How autoreceptors contribute to maintaining a stable output of rhythmically active neuronal circuits is poorly understood. Here, we examine this issue in a dopamine population, spontaneously oscillating hypothalamic rat (TIDA) neurons, that underlie neuroendocrine control of reproduction and neuroleptic side effects. Activation of dopamine receptors of the type 2 family (D2Rs) at the cell-body level slowed TIDA oscillations through two mechanisms. First, they prolonged the depolarizing phase through a combination of presynaptic increases in inhibition and postsynaptic hyperpolarization. Second, they extended the discharge phase through presynaptic attenuation of calcium currents and decreased synaptic inhibition. Dopamine reuptake blockade similarly reconfigured the oscillation, indicating that ambient somatodendritic transmitter concentration determines electrical behavior. In the absence of D2R feedback, however, discharge was abolished by depolarization block. These results indicate the existence of an ultra-short feedback loop whereby neuroendocrine dopamine neurons tune network behavior to echoes of their own activity, reflected in ambient somatodendritic dopamine, and also suggest a mechanism for antipsychotic side effects.
自身受体如何有助于维持节律性活动的神经回路的稳定输出,目前还知之甚少。在此,我们在一组多巴胺神经元中研究了这个问题,这些神经元是下丘脑大鼠(TIDA)神经元,它们自发振荡,是生殖神经内分泌控制和抗精神病药物副作用的基础。在细胞体水平激活2型家族多巴胺受体(D2Rs)通过两种机制减缓了TIDA振荡。首先,它们通过突触前抑制增加和突触后超极化的组合延长了去极化阶段。其次,它们通过突触前钙电流衰减和突触抑制减少延长了放电阶段。多巴胺再摄取阻断同样重构了振荡,表明周围树突体递质浓度决定电行为。然而,在没有D2R反馈的情况下,去极化阻滞会消除放电。这些结果表明存在一个超短反馈回路,通过该回路神经内分泌多巴胺神经元将网络行为调整为自身活动的回声,这反映在周围树突体多巴胺中,并且还提示了抗精神病药物副作用的一种机制。