Alagona Giovanna, Coco Marinella, Rapisarda Giuseppe, Costanzo Erminio, Maci Tiziana, Restivo Domenico, Maugeri Antonino, Perciavalle Vincenzo
Unità Operativa di Neurologia, Azienda Ospedaliera Cannizzaro, Catania, Italy.
Neurosci Lett. 2009 Jan 30;450(2):111-3. doi: 10.1016/j.neulet.2008.11.064. Epub 2008 Dec 6.
The objective was to study whether repetitive transcranial magnetic stimulation (rTMS) of the motor cortex could induce modification of peripheral blood lactate values. Nineteen young healthy volunteers were included; during the study, all subjects were at rest, sitting on a comfortable armchair. The muscular activation was evaluated by continuous electromyographic record. TMS was performed by using a circular coil at the vertex. Resting motor threshold (rMT) was defined as the lowest TMS intensity able to induce motor responses of an amplitude >50 microV in the relaxed contralateral target muscle in approximately 50% of 20 consecutive stimuli. Venous blood lactate values were measured before, immediately after and 10 min after a single session of low frequencies (1Hz for 15 min) rTMS (LF rTMS) or high frequency (20 Hz for 15 min) rTMS (HF rTMS). As expected, LF rTMS induced a decrease of motor cortex excitability, whereas HF rTMS evoked an increase of motor cortex excitability. However, in the present investigation we observed that both conditions are associated to a significant increase of blood lactate. Since in our experimental conditions we can exclude a muscular production of lactate, the significant increment of peripheral blood lactate values, observed 10 min after the end of the rTMS session, is probably due to the crossing by brain-produced lactate of the blood-brain barrier.
目的是研究对运动皮层进行重复经颅磁刺激（rTMS）是否能引起外周血乳酸值的改变。纳入了19名年轻健康志愿者；在研究过程中，所有受试者均处于休息状态，坐在舒适的扶手椅上。通过连续肌电图记录评估肌肉激活情况。使用置于头顶的圆形线圈进行经颅磁刺激（TMS）。静息运动阈值（rMT）定义为在连续20次刺激中约50%的情况下，能够在对侧放松的目标肌肉中诱发幅度>50微伏运动反应的最低TMS强度。在单次低频（1Hz，持续15分钟）rTMS（低频rTMS）或高频（20Hz，持续15分钟）rTMS（高频rTMS）刺激前、刺激后即刻以及刺激后10分钟测量静脉血乳酸值。正如预期的那样，低频rTMS导致运动皮层兴奋性降低，而高频rTMS引起运动皮层兴奋性增加。然而，在本研究中我们观察到，两种情况均与血乳酸显著升高有关。由于在我们的实验条件下可以排除乳酸由肌肉产生，在rTMS刺激结束后10分钟观察到的外周血乳酸值显著升高，可能是由于脑产生的乳酸穿过血脑屏障所致。
