Department of Physiology, Saga Medical School, 5-1-1 Nabeshima, Saga 849-8501, Japan.
Biochem Biophys Res Commun. 2011 Jul 15;410(4):841-5. doi: 10.1016/j.bbrc.2011.06.075. Epub 2011 Jun 15.
We examined the effects of TRPV1 agonists olvanil and piperine on glutamatergic spontaneous excitatory transmission in the substantia gelatinosa (SG) neurons of adult rat spinal cord slices with the whole-cell patch-clamp technique. Bath-applied olvanil did not affect the frequency and amplitude of spontaneous excitatory postsynaptic current (sEPSC), and unchanged holding currents at -70 mV. On the other hand, superfusing piperine reversibly and concentration-dependently increased sEPSC frequency (half-maximal effective concentration: 52.3 μM) with a minimal increase in its amplitude. This sEPSC frequency increase was almost repetitive at an interval of more than 20 min. Piperine at a high concentration produced an inward current in some neurons. The facilitatory effect of piperine was blocked by TRPV1 antagonist capsazepine. It is concluded that piperine but not olvanil activates TRPV1 channels in the central terminals of primary-afferent neurons, resulting in an increase in the spontaneous release of l-glutamate onto SG neurons.
我们使用全细胞膜片钳技术研究了 TRPV1 激动剂 olvanil 和胡椒碱对成年大鼠脊髓切片中胶状质（SG）神经元中谷氨酸能自发性兴奋性传递的影响。灌流 olvanil 不影响自发性兴奋性突触后电流（sEPSC）的频率和幅度，并且在-70 mV 时保持电流不变。另一方面，胡椒碱可逆且浓度依赖性地增加 sEPSC 频率（半数有效浓度：52.3 μM），而其幅度仅有微小增加。这种 sEPSC 频率增加在间隔超过 20 分钟的时间内几乎是重复的。胡椒碱在高浓度下会在一些神经元中产生内向电流。TRPV1 拮抗剂辣椒素可阻断胡椒碱的促发作用。结论是，胡椒碱而不是 olvanil 激活初级传入神经元的中枢末端的 TRPV1 通道，导致 l-谷氨酸在 SG 神经元上的自发性释放增加。
