Department of Ophthalmology, David Geffen School of Medicine (DGSOM), University of California, Los Angeles (UCLA), Los Angeles, California, USA.
School of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
Chronobiol Int. 2022 Apr;39(4):513-524. doi: 10.1080/07420528.2021.2014516. Epub 2022 Jan 4.
Circadian rhythms in core body temperature (CBT) have been widely studied, but fewer studies have explored higher-frequency (ultradian) rhythms in detail. We analyzed CBT recordings from young and middle-aged wild-type mice as well as from the Q175 model of Huntington's disease (HD), at sufficient temporal resolution to address the question of ultradian rhythms. We used model selection methods to show that the overall circadian pattern was better fit by a square wave than a sine wave. Then, using Fourier analysis of the CBT rhythms, we identified the spectral signature of an 8-hour oscillation that occurs in the night but not the day, an observation that can be confirmed by direct inspection of the rhythms. This diurnal amplitude modulation of the 8-hour rhythm was lost with aging as well as in the HD model. Thus, the impact of aging and disease is seen here in the loss of the ability to separate rhythms into a daytime phase and a nighttime phase. These findings raise the possibility that ultradian rhythms in CBT may be a useful biomarker for the pathology within the central nervous system.
核心体温（CBT）的昼夜节律已经得到了广泛的研究，但很少有研究详细探讨更高频率（超日周期）的节律。我们分析了年轻和中年野生型小鼠以及亨廷顿病（HD）的 Q175 模型的 CBT 记录，时间分辨率足以解决超日周期的问题。我们使用模型选择方法表明，整体昼夜节律模式更适合方形波而不是正弦波。然后，我们使用 CBT 节律的傅立叶分析，确定了 8 小时振荡的光谱特征，该振荡发生在夜间而不是白天，通过直接观察节律可以证实这一观察结果。这种 8 小时节律的日振幅调制在衰老和 HD 模型中都会丢失。因此，衰老和疾病的影响在这里表现为失去将节律分为白天和夜间阶段的能力。这些发现提出了这样一种可能性，即 CBT 中的超日周期可能是中枢神经系统内病理学的有用生物标志物。
