Department of Neurology, Vanderbilt University Medical Center, 6140 MRB III, 465 21st Ave South, Nashville, TN 37232-8552, United States.
J Neurosci Methods. 2010 Sep 30;192(1):110-4. doi: 10.1016/j.jneumeth.2010.07.014. Epub 2010 Jul 21.
Transient electrical impulses are conventionally used to elicit physiological responses in excitable tissues. While electrical stimulation has many advantages, it requires an electrode-tissue interface, exhibits relatively low spatial selectivity and always produces a "stimulus artifact". Recently, it has been shown that pulsed, low-energy infrared laser light can evoke nerve, muscle and sensory responses similar to those induced by traditional electrical stimulation in a contact-free, damage-free, artifact-free and spatially selective manner. However, the effect of transient infrared laser light on neurotransmission in the CNS is still largely unknown. Here, we tested the effect of infrared laser light on GABAergic neurotransmission. We recorded spontaneous inhibitory postsynaptic currents (sIPSCs) from cultured rat cortical neurons prior to and after infrared laser stimulation. Using transient infrared laser light, we either stimulated the neuronal soma that had axonal projections to the recorded neuron or directly stimulated the axons that projected to the recorded neuron. Optical stimulation led to enhanced amplitude, decreased decay time constant and increased frequency of sIPSCs. These alterations of sIPSC properties produced by optical stimulation were specifically mediated by GABA(A) receptors and caused by the transient laser light per se since no exogenous substances such as caged compounds were used. These data show that optical stimulation using transient infrared laser light can alter GABAergic neurotransmission and demonstrate that it may be an alternative approach to electrical stimulation in studying GABAergic function.
传统上，瞬态电脉冲被用于激发可兴奋组织中的生理反应。虽然电刺激有许多优点，但它需要一个电极-组织界面，表现出相对较低的空间选择性，并且总是产生“刺激伪迹”。最近，已经表明，脉冲、低能量红外激光光可以以非接触、无损伤、无伪迹和空间选择性的方式，诱发出类似于传统电刺激诱导的神经、肌肉和感觉反应。然而，瞬态红外激光光对中枢神经系统中神经递质传递的影响在很大程度上仍然未知。在这里，我们测试了红外激光光对 GABA 能神经递质传递的影响。我们在红外激光刺激前后记录了培养的大鼠皮质神经元的自发性抑制性突触后电流（sIPSCs）。使用瞬态红外激光光，我们刺激具有向记录神经元投射的轴突的神经元胞体，或者直接刺激投射到记录神经元的轴突。光刺激导致 sIPSCs 的幅度增加、衰减时间常数减小和频率增加。光学刺激引起的 sIPSC 特性的这些改变是由 GABA(A)受体特异性介导的，并且是由瞬态激光本身引起的，因为没有使用诸如笼状化合物等外源性物质。这些数据表明，使用瞬态红外激光的光刺激可以改变 GABA 能神经递质传递，并证明它可能是研究 GABA 能功能的电刺激的替代方法。
