Kwon Hyung-Bae, Castillo Pablo E
Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Neuron. 2008 Jan 10;57(1):108-20. doi: 10.1016/j.neuron.2007.11.024.
The mossy fiber to CA3 pyramidal cell synapse (mf-CA3) provides a major source of excitation to the hippocampus. Thus far, these glutamatergic synapses are well recognized for showing a presynaptic, NMDA receptor-independent form of LTP that is expressed as a long-lasting increase of transmitter release. Here, we show that in addition to this "classical" LTP, mf-CA3 synapses can undergo a form of LTP characterized by a selective enhancement of NMDA receptor-mediated transmission. This potentiation requires coactivation of NMDA and mGlu5 receptors and a postsynaptic calcium rise. Unlike classical LTP, expression of this mossy fiber LTP is due to a PKC-dependent recruitment of NMDA receptors specifically to the mf-CA3 synapse via a SNARE-dependent process. Having two mechanistically different forms of LTP may allow mf-CA3 synapses to respond with more flexibility to the changing demands of the hippocampal network.
苔藓纤维至CA3锥体细胞突触(mf-CA3)是海马体兴奋的主要来源。到目前为止,这些谷氨酸能突触因表现出一种不依赖NMDA受体的突触前形式的长时程增强(LTP)而广为人知,这种LTP表现为递质释放的持久增加。在此,我们表明,除了这种“经典”LTP外,mf-CA3突触还可经历一种以NMDA受体介导的传递选择性增强为特征的LTP形式。这种增强需要NMDA和mGlu5受体的共同激活以及突触后钙升高。与经典LTP不同,这种苔藓纤维LTP的表达是由于PKC依赖的NMDA受体通过依赖SNARE的过程特异性募集到mf-CA3突触。具有两种机制不同的LTP形式可能使mf-CA3突触能够更灵活地应对海马体网络不断变化的需求。