Extracellular concentrations of acetylcholine (ACh) in the prefrontal cortex displayed a circadian rhythm, with a maximum increase in the dark phase of the light:dark cycle. The increase in ACh related well to the circadian rhythm of the same rats in which a maximal increase of locomotor activity in the dark phase also was observed. Local perfusion of melatonin (200-500 microm), in a dose-dependent manner, disrupted the ACh rhythm in the prefrontal cortex but did not affect the circadian rhythm of locomotor activity. It is suggested that the change in the cholinergic transmission during a circadian period in the prefrontal cortex may be under the control of the biological clock through the action of melatonin; however, the prefrontal cortical ACh cycle seems not to be related to the regulation of locomotor activity.

中文翻译：

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褪黑激素灌注到前额叶皮层会破坏乙酰胆碱的昼夜节律，但不会破坏运动活性。

前额叶皮层中乙酰胆碱（ACh）的细胞外浓度显示了昼夜节律，在明暗循环的暗相中最大增加。ACh的增加与相同大鼠的昼夜节律相关性很好，其中在黑暗阶段也观察到运动活动的最大增加。褪黑素（200-500微米）的局部灌注以剂量依赖性方式破坏了前额叶皮层中的ACh节律，但并未影响运动活动的昼夜节律。建议在前额叶皮层的昼夜节律期间胆碱能传递的变化可能是通过褪黑激素作用在生物钟的控制下进行的。然而，前额叶皮质ACh周期似乎与运动活性的调节无关。