Musleh W Y, Shahi K, Baudry M
Neuroscience Program, USC, Los Angeles 90089-2520.
Synapse. 1993 Apr;13(4):370-5. doi: 10.1002/syn.890130409.
Nitric oxide (NO) has recently been proposed to act as a retrograde messenger to produce long-term potentiation (LTP) in hippocampal area CA1. This notion is based largely on the absence of LTP when hippocampal slices are incubated in the presence of inhibitors of NO synthase (NOS) or of NO scavengers. In the present study, we tested the effects of such compounds on both the induction and maintenance of LTP in field CA1 of hippocampal slices. Incubation of slices in the presence of N-methyl-L-arginine (MLA) or L-nitro-arginine (LNA), two inhibitors of NOS, or in the presence of hemoglobin (Hb), a NO scavenger, produced a large reduction in the magnitude of LTP induced by a theta burst stimulation (TBS) paradigm. These compounds had no effect on the degree of paired-pulse facilitation but produced a significant reduction of the facilitation of postsynaptic responses occurring during TBS. On the other hand, MLA did not prevent the potentiation induced by application of tetraethylammonium (TEA). These results suggest that the inhibition of LTP produced by these agents could be due to an effect on a physiological mechanism that triggers LTP and not necessarily on an event that follows the triggering step.
一氧化氮（NO）最近被认为作为一种逆行信使在海马体CA1区产生长时程增强（LTP）。这一观点很大程度上基于当海马体切片在一氧化氮合酶（NOS）抑制剂或NO清除剂存在的情况下孵育时LTP缺失。在本研究中，我们测试了这类化合物对海马体切片CA1区LTP的诱导和维持的影响。在两种NOS抑制剂N-甲基-L-精氨酸（MLA）或L-硝基精氨酸（LNA）存在的情况下，或在一种NO清除剂血红蛋白（Hb）存在的情况下孵育切片，由θ波爆发刺激（TBS）模式诱导的LTP幅度大幅降低。这些化合物对双脉冲易化程度没有影响，但在TBS期间发生的突触后反应易化有显著降低。另一方面，MLA并不阻止由应用四乙铵（TEA）诱导的增强。这些结果表明，这些药剂对LTP的抑制可能是由于对触发LTP的生理机制的影响，而不一定是对触发步骤之后的事件的影响。
