Glucose and lactate provide energy for cellular function in the brain and serve as an important carbon source in the synthesis of a variety of biomolecules. Thus, there is a critical need to quantitatively monitor these molecules in situ on a time scale commensurate with neuronal function. In this work, carbon-fiber microbiosensors were coupled with fast-scan cyclic voltammetry to monitor glucose and lactate fluctuations at a discrete site within rat striatum upon electrical stimulation of the midbrain projection to the region. Systematic variation of stimulation parameters revealed the distinct dynamics by which glucose and lactate responded to the metabolic demand of synaptic function. Immediately upon stimulation, extracellular glucose and lactate availability rapidly increased. If stimulation was sufficiently intense, concentrations then immediately fell below baseline in response to incurred metabolic demand. The dynamics were dependent on stimulation frequency, such that more robust fluctuations were observed when the same number of pulses was delivered at a higher frequency. The rates at which glucose was supplied to, and depleted from, the local recording region were dependent on stimulation intensity, and glucose dynamics led those of lactate in response to the most substantial stimulations. Glucose fluctuated over a larger concentration range than lactate as stimulation duration increased, and glucose fell further from baseline concentrations. These real-time measurements provide an unprecedented direct comparison of glucose and lactate dynamics in response to metabolic demand elicited by neuronal activation.

葡萄糖和乳酸为大脑中的细胞功能提供能量，并作为多种生物分子合成的重要碳源。因此，迫切需要在与神经元功能相称的时间尺度上原位定量监测这些分子。在这项工作中，碳纤维微生物传感器与快速扫描循环伏安法相结合，以监测大鼠纹状体内离散部位在电刺激中脑投射到该区域时的葡萄糖和乳酸波动。刺激参数的系统变化揭示了葡萄糖和乳酸响应突触功能代谢需求的独特动态。受到刺激后，细胞外葡萄糖和乳酸的利用率立即迅速增加。如果刺激足够强烈，浓度就会立即降至基线以下，以响应所产生的代谢需求。动力学取决于刺激频率，因此当以更高的频率传递相同数量的脉冲时，会观察到更强烈的波动。向局部记录区域供应和消耗葡萄糖的速率取决于刺激强度，并且葡萄糖动力学导致乳酸响应最强烈的刺激。随着刺激持续时间的增加，葡萄糖在比乳酸更大的浓度范围内波动，并且葡萄糖从基线浓度进一步下降。这些实时测量提供了前所未有的葡萄糖和乳酸动态的直接比较，以响应神经元激活引起的代谢需求。