Lavoute Cécile, Weiss Michel, Rostain Jean-Claude
Université de la Méditerranée et IMNSSA, EA 3280, Physiopathologie et Action Thérapeutique des Gaz Sous Pression, Institut de Recherche Jean-Roche, Faculté de Médecine Nord, Bd P. Dramard, 13015 Marseille, France.
Brain Res. 2005 Sep 14;1056(1):36-42. doi: 10.1016/j.brainres.2005.07.004.
Previous studies have demonstrated disruptions of motor activities and a decrease of extracellular dopamine level in the striatum of rats exposed to high pressure of nitrogen. Men exposed to nitrogen pressure develop also motor and cognitive disturbances related to inert gas narcosis. After repetitive exposures, adaptation to narcosis was subjectively reported. To study the effects of repetitive exposures to hyperbaric nitrogen-oxygen, male Sprague-Dawley rats were implanted in the striatum with multifiber carbon dopamine-sensitive electrodes. After recovery from surgery, free-moving rats were exposed for 2 h up to 3 MPa of nitrogen-oxygen mixture before and after one daily exposure to 1 MPa of nitrogen-oxygen, for 5 consecutive days. Dopamine release was measured by differential pulse voltammetry and motor activities were quantified using piezo-electric captor. At the first exposure to 3 MPa, the striatal dopamine level decreased during the compression (-15%) to reach -20% during the stay at 3 MPa. Motor activities were increased during compression (+15%) and the first 60 min at constant pressure (+10%). In contrast, at the second exposure to 3 MPa, an increase of dopamine of +15% was obtained during the whole exposure. However, total motor activities remained unchanged as compared to the first exposure. Our results confirm that nitrogen exposure at 3 MPa led to a decreased striatal dopamine release and increased motor disturbances in naïve rats. Repetitive exposures to 1 MPa of nitrogen induced a reversal effect on the dopamine release which suggests a neurochemical change at the level of the neurotransmitter regulation processes of the basal ganglia. In contrast, motor activity remained quantitatively unchanged, thus suggesting that dopamine is not involved alone in modulating these motor disturbances.
先前的研究表明，暴露于高氮压力下的大鼠，其运动活动会受到干扰，纹状体中的细胞外多巴胺水平会降低。暴露于氮压力下的男性也会出现与惰性气体麻醉相关的运动和认知障碍。在重复暴露后，主观报告了对麻醉的适应性。为了研究重复暴露于高压氮氧环境的影响，将雄性Sprague-Dawley大鼠的纹状体植入多纤维碳多巴胺敏感电极。手术后恢复后，自由活动的大鼠在每天暴露于1 MPa氮氧环境前后，先暴露于高达3 MPa的氮氧混合物中2小时，持续5天。通过差分脉冲伏安法测量多巴胺释放，并使用压电传感器对运动活动进行量化。在首次暴露于3 MPa时，压缩过程中纹状体多巴胺水平下降（-15%），在3 MPa停留期间降至-20%。压缩过程中运动活动增加（+15%），在恒定压力下的前60分钟增加（+10%）。相比之下，在第二次暴露于3 MPa时，整个暴露过程中多巴胺增加了+15%。然而，与第一次暴露相比，总运动活动保持不变。我们的结果证实，3 MPa的氮暴露导致初发大鼠纹状体多巴胺释放减少和运动障碍增加。重复暴露于1 MPa的氮对多巴胺释放产生了逆转作用，这表明基底神经节神经递质调节过程水平发生了神经化学变化。相比之下，运动活动在数量上保持不变，因此表明多巴胺并非单独参与调节这些运动障碍。
