Norra Christine, Becker Stefanie, Herpertz Sabine C, Kunert Hanns Jürgen
Department of Psychiatry and Psychotherapy, University Hospital RWTH, Aachen, Germany.
Eur Arch Psychiatry Clin Neurosci. 2008 Feb;258(1):1-9. doi: 10.1007/s00406-007-0753-z. Epub 2007 Sep 27.
Previous studies suggest an important role for serotonergic (5-HT) modulation of the acoustic startle reflex (ASR) and prepulse inhibition (PPI). Acute challenge of brain serotonin by means of tryptophan depletion test (TDT) represents an established human challenge tool for temporary reduction of tryptophan (-TRP) levels and central nervous serotonin. Under these experimental conditions, PPI was found attenuated in males, but greater biochemical effects of TDT in the central nervous system of females are known. Therefore, in order to explore influence of 5-HT on various standard startle parameters in females, 16 young healthy females participated in a double-blind, cross-over TDT study. Acoustic stimuli were presented in 15 pulse-alone trials (100 dB, 40 ms) randomly followed by 25 pulse-alone or prepulse (70 dB, 30 ms; 120 ms interval) trials alongside electromyographic eyeblink recordings and mood state assessments. During 81% depletion of free plasma TRP, mean ASR magnitudes were significantly reduced compared to control (+TRP) condition while there were no differences in habituation or PPI nor did startle parameters correlate with mood states. Changes of plasma TRP and mood states correlated in tendency negatively in (-TRP) for depression and positively in (+TRP) for fatigue. In conclusion, this first study of startle parameters after TDT in a homogenous female population demonstrates that depletion of brain 5-HT in women only influences ASR.
先前的研究表明，血清素能（5-羟色胺，5-HT）对听觉惊吓反射（ASR）和前脉冲抑制（PPI）具有重要调节作用。通过色氨酸耗竭试验（TDT）对大脑血清素进行急性挑战，是一种既定的人类挑战工具，可用于暂时降低色氨酸（-TRP）水平和中枢神经系统血清素。在这些实验条件下，发现男性的PPI减弱，但已知TDT对女性中枢神经系统具有更大的生化影响。因此，为了探究5-HT对女性各种标准惊吓参数的影响，16名年轻健康女性参与了一项双盲、交叉TDT研究。在15次单独脉冲试验（100分贝，40毫秒）中呈现听觉刺激，随后随机进行25次单独脉冲或前脉冲（70分贝，30毫秒；间隔120毫秒）试验，同时记录肌电图眨眼情况并评估情绪状态。在游离血浆TRP耗竭81%期间，与对照（+TRP）条件相比，平均ASR幅度显著降低，而在习惯化或PPI方面没有差异，惊吓参数也与情绪状态无关。血浆TRP和情绪状态的变化在（-TRP）时对抑郁呈负相关趋势，在（+TRP）时对疲劳呈正相关趋势。总之，这项对同质女性群体进行TDT后惊吓参数的首次研究表明，女性大脑5-HT的耗竭仅影响ASR。
