Rodríguez-Moreno A
División de Neurociencias, Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide, Sevilla, Spain.
Rev Neurol. 2006;42(5):282-7.
To describe the state of the art with regard to the physiology of kainate-like glutamate receptors as modulators in glutamatergic excitatory synaptic transmission in the hippocampus.
Kainate receptors modulate the release of glutamate in the hippocampus in the different synapses that have been studied to date. Their activation can produce a decrease or an increase in glutamate release according to the synapse under study and both types of modulation (increase or decrease) can take place even within the same synaptic connection, depending on the agonist concentration reached by the receptors. Thus, in the synapses that are established among the mossy fibres and the pyramidal neurones in region CA3, high concentrations (> 100 nM) of kainate trigger a drop in glutamate release, whereas low concentrations (< 50 nM) give rise to an increased release of the same neurotransmitter. These actions carried out by the kainate receptors are presynaptic and both ionotropic and metabotropic mechanisms have been proposed to explain them.
Kainate receptors act in the hippocampus as modulators of glutamate release, by either increasing or decreasing it. They therefore help to keep the balance of neuronal excitability, also play a part in neuronal plasticity processes (LTP and LTD) and can trigger, under abnormal conditions, a notable imbalance of this excitability and give rise to epileptic-type firing patterns, among other disorders.
描述作为海马体谷氨酸能兴奋性突触传递调节剂的红藻氨酸样谷氨酸受体的生理学研究现状。
红藻氨酸受体在迄今已研究的海马体不同突触中调节谷氨酸的释放。根据所研究的突触不同，其激活可导致谷氨酸释放减少或增加，并且这两种调节类型（增加或减少）甚至可在同一突触连接内发生，这取决于受体达到的激动剂浓度。因此，在CA3区苔藓纤维与锥体神经元之间形成的突触中，高浓度（>100 nM）的红藻氨酸会引发谷氨酸释放下降，而低浓度（<50 nM）则会导致相同神经递质释放增加。红藻氨酸受体的这些作用是突触前的，并且已经提出离子型和代谢型机制来解释它们。
红藻氨酸受体在海马体中作为谷氨酸释放的调节剂发挥作用，可增加或减少其释放。因此，它们有助于维持神经元兴奋性的平衡，也参与神经元可塑性过程（长时程增强和长时程抑制），并且在异常情况下可引发这种兴奋性的显著失衡，导致癫痫样放电模式等多种紊乱。
