Helen Wills Neuroscience Institute, University of California, Berkeley, California.
Department of Psychology, University of California, Berkeley, California.
J Biol Rhythms. 2022 Aug;37(4):442-454. doi: 10.1177/07487304221092715. Epub 2022 May 3.
Biological rhythms in core body temperature (CBT) provide informative markers of adolescent development under controlled laboratory conditions. However, it is unknown whether these markers are preserved under more variable, semi-naturalistic conditions, and whether CBT may therefore prove useful in a real-world setting. To evaluate this possibility, we examined fecal steroid concentrations and CBT rhythms from pre-adolescence (p26) through early adulthood (p76) in intact male and female Wistar rats under natural light and climate at the Stephen Glickman Field Station for the Study of Behavior, Ecology and Reproduction. Despite greater environmental variability, CBT markers of pubertal onset and its rhythmic progression were comparable with those previously reported in laboratory conditions in female rats and extend actigraphy-based findings in males. Specifically, sex differences emerged in CBT circadian rhythm (CR) power and amplitude prior to pubertal onset and persisted into early adulthood, with females exhibiting elevated CBT and decreased CR power compared with males. Within-day (ultradian rhythm [UR]) patterns also exhibited a pronounced sex difference associated with estrous cyclicity. Pubertal onset, defined by vaginal opening, preputial separation, and sex steroid concentrations, occurred later than previously reported under lab conditions for both sexes. Vaginal opening and increased fecal estradiol concentrations were closely tied to the commencement of 4-day oscillations in CBT and UR power. By contrast, preputial separation and the first rise in testosterone concentration were not associated with adolescent changes to CBT rhythms in male rats. Together, males and females exhibited unique temporal patterning of CBT and sex steroids across pubertal development, with tractable associations between hormonal concentrations, external development, and temporal structure in females. The preservation of these features outside the laboratory supports CBT as a strong candidate for translational pubertal monitoring under semi-naturalistic conditions in females.
核心体温 (CBT) 的生物节律为在受控实验室条件下研究青少年发育提供了有价值的标志物。然而，尚不清楚这些标志物是否在更具变异性的半自然条件下得到保留，以及 CBT 是否因此可在现实环境中得到应用。为了评估这种可能性，我们在斯蒂芬·格里克曼行为、生态和生殖研究野外站，在自然光和气候条件下，对雄性和雌性 Wistar 大鼠从青春期前 (p26) 到成年早期 (p76) 的粪便类固醇浓度和 CBT 节律进行了研究。尽管环境变异性更大，但青春期开始及其节律进展的 CBT 标志物与以前在雌性大鼠的实验室条件下报告的标志物相似，并扩展了基于活动记录仪的雄性大鼠的发现。具体而言，在青春期前，CBT 昼夜节律 (CR) 功率和幅度的性别差异就已经出现，并持续到成年早期，与雄性相比，雌性的 CBT 升高，CR 功率降低。日内 (超昼夜节律 [UR]) 模式也表现出与发情周期相关的明显性别差异。青春期的开始，通过阴道开口、包皮分离和性激素浓度来定义，比以前在实验室条件下报告的男女两性都要晚。阴道开口和粪便雌二醇浓度的增加与 CBT 和 UR 功率的 4 天波动的开始密切相关。相比之下，包皮分离和睾酮浓度的首次升高与雄性大鼠青春期 CBT 节律变化无关。总之，雄性和雌性在青春期发育过程中表现出独特的 CBT 和性激素时间模式，并且在女性中，激素浓度、外部发育和时间结构之间存在可追踪的关联。这些特征在实验室之外得到保留，支持 CBT 成为在半自然条件下对女性进行青春期监测的有力候选者。
