Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, United Kingdom.
J Neurosci. 2011 Apr 13;31(15):5777-81. doi: 10.1523/JNEUROSCI.6265-10.2011.
Several subtypes of interneurons in the feedback circuit in stratum oriens of the hippocampus exhibit NMDA receptor-independent long-term potentiation (LTP) at glutamatergic synapses made by local pyramidal neurons. LTP has been reported with both "Hebbian" and "anti-Hebbian" induction protocols, where high-frequency presynaptic stimulation is paired with either postsynaptic depolarization or hyperpolarization. Do these phenomena represent distinct forms of plasticity, dependent on group I metabotropic receptors (mGluRs) and rectifying Ca2+ -permeable AMPA receptors, respectively? Blockade of either mGluR1 or mGluR5 prevented anti-Hebbian LTP induction in stratum oriens interneurons in rat hippocampal slices. Exogenous activation of group I mGluRs by the selective agonist (S)-3,5-dihydroxyphenylglycine (DHPG) was unable to induce LTP on its own, and instead depressed excitatory transmission. However, when paired with postsynaptic hyperpolarization, DHPG or the group I metabotropic receptor (mGluR5)-selective agonist (R,S)-2-chloro-5-hydroxyphenylglycine (CHPG) elicited a delayed long-lasting potentiation, which was accompanied by a decrease in paired-pulse facilitation. Anti-Hebbian LTP occluded the effect of DHPG paired with hyperpolarization, implying that the induction cascades triggered by both conjunctions of stimuli converge on common expression mechanisms.
在海马回的放射层中的反馈回路中的几种中间神经元在局部锥体神经元形成的谷氨酸能突触上表现出 NMDA 受体非依赖性的长时程增强（LTP）。已经报道了具有“赫布型”和“反赫布型”诱导方案的 LTP，其中高频突触前刺激与突触后去极化或超极化配对。这些现象是否代表依赖于 I 组代谢型谷氨酸受体（mGluR）和整流 Ca2+ 通透性 AMPA 受体的不同形式的可塑性？分别阻断 mGluR1 或 mGluR5 可防止大鼠海马切片中放射层中间神经元的反赫布型 LTP 诱导。I 组 mGluR 的选择性激动剂（S）-3,5-二羟基苯甘氨酸（DHPG）的外源性激活本身不能诱导 LTP，反而抑制了兴奋性传递。然而，当与突触后超极化配对时，DHPG 或 I 组代谢型谷氨酸受体（mGluR5）选择性激动剂（R，S）-2-氯-5-羟基苯甘氨酸（CHPG）会引发延迟的长时程增强，伴随着对配对脉冲易化的抑制。反赫布型 LTP 阻断了 DHPG 与超极化配对的作用，这意味着两种刺激组合引发的诱导级联都集中在共同的表达机制上。
