Krase W, Koch M, Schnitzler H U
Universität Tübingen, Germany.
Behav Brain Res. 1994 Jul 29;63(1):81-8. doi: 10.1016/0166-4328(94)90053-1.
The acoustic startle response (ASR) can be enhanced by administration of footshocks (sensitization). The neural mechanisms underlying this effect are largely unknown. A previous electrophysiological study (Kungel et al., Brain Res., 643 (1994) 29-39) has shown that the neuropeptide substance P (SP) increases the responsiveness to acoustic stimuli of neurons in the caudal pontine reticular nucleus (PnC). Since the PnC is an important part of the primary acoustic startle circuit, we hypothesized that SP is involved in the enhancement of the ASR by electric footshocks. We tested this hypothesis in different experiments by locally injecting SP and SP-antagonists into the PnC of freely moving rats. The present data show that SP (0.5 pmol-1 nmol) locally injected into the PnC dose-dependently increases the amplitude of the ASR in rats. This effect was antagonized by pretreatment with the SP-antagonist CP-96,345. Furthermore, we show that the sensitization of the ASR by 0.6 mA-footshocks can be blocked by local microinjections of the SP-antagonists CP-96,345 (5 pmol-10 nmol) or CP-99,994 (0.5 nmol-100 nmol) into the PnC. Possible pathways relevant for the sensitization of the ASR are discussed.
给予足部电击（致敏作用）可增强听觉惊吓反应（ASR）。这种效应背后的神经机制在很大程度上尚不清楚。先前的一项电生理学研究（Kungel等人，《脑研究》，643（1994）29 - 39）表明，神经肽P物质（SP）可增强尾侧脑桥网状核（PnC）中神经元对听觉刺激的反应性。由于PnC是初级听觉惊吓回路的重要组成部分，我们推测SP参与了电击足部增强ASR的过程。我们通过在自由活动大鼠的PnC中局部注射SP和SP拮抗剂，在不同实验中对这一假设进行了检验。目前的数据表明，局部注射到PnC中的SP（0.5皮摩尔 - 1纳摩尔）可剂量依赖性地增加大鼠ASR的幅度。SP拮抗剂CP - 96,345预处理可拮抗这种效应。此外，我们还表明，通过在PnC中局部微量注射SP拮抗剂CP - 96,345（5皮摩尔 - 10纳摩尔）或CP - 99,994（0.5纳摩尔 - 100纳摩尔），可阻断0.6毫安足部电击对ASR的致敏作用。文中还讨论了与ASR致敏作用相关的可能途径。
