视交叉上核作为中央时钟，如何与肝脏等外周时钟保持同步？
How does the suprachiasmatic nucleus as master clock keep peripheral clocks such as the liver in step?
视网膜内含黑视素的神经节细胞把光信息经视网膜下丘脑束传给视交叉上核，使其相位锁定于外界明暗周期。视交叉上核再通过多条通路把时间信号输出：自主神经支配、下丘脑-垂体-肾上腺轴产生的糖皮质激素节律、体温波动以及对进食-活动节律的控制，都能重置外周组织中的同一套时钟基因。由于进食时间是肝脏时钟的强授时因子，白天进食的夜行动物会出现肝脏时钟与视交叉上核相位分离，这解释了不规律进食如何造成组织间的内部失同步。
Melanopsin-containing retinal ganglion cells send light information along the retinohypothalamic tract to the suprachiasmatic nucleus, locking its phase to the external light-dark cycle. The nucleus then broadcasts time through several channels: autonomic innervation, the glucocorticoid rhythm generated via the hypothalamic-pituitary-adrenal axis, body temperature cycles and control of feeding and activity rhythms, all of which can reset the same clock genes in peripheral tissues. Because feeding time is a powerful cue for the liver clock, nocturnal animals fed during the day show hepatic rhythms uncoupled from the suprachiasmatic nucleus, which explains how irregular meal timing creates internal desynchrony between tissues.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Mohawk JA, Green CB, Takahashi JS. Central and peripheral circadian clocks in mammals. Annual Review of Neuroscience (2012) 35:445-462
Mohawk JA, Green CB, Takahashi JS. Central and peripheral circadian clocks in mammals. Annual Review of Neuroscience (2012) 35:445-462
独立核验依据 · Independent verification: 核验依据 1 DOI 10.1146/annurev-neuro-060909-153128
#视交叉上核 #外周时钟 #授时因子 #进食节律
不冬眠的小鼠也能被诱导进入类冬眠状态，这揭示了什么神经机制？
Mice that do not naturally hibernate can be driven into a hibernation-like state; what neural mechanism does this reveal?
2020 年两项独立研究发现，激活下丘脑中特定的神经元群可诱导小鼠进入体温和代谢率大幅下降的类冬眠状态：一项工作定位到下丘脑视前区表达 Adcyap1 的神经元，另一项发现下丘脑前部的兴奋性神经元集群可维持数天的低体温低代谢。这说明蛰伏并非被动的低温结果，而是由中枢主动下调体温设定点驱动的调控程序，且相关环路在非冬眠物种中依然保留。该发现为医学诱导低代谢用于器官保护和急救提供了神经靶点。
Two independent studies in 2020 showed that activating specific hypothalamic neuron populations drives mice into a hibernation-like state with sharply lowered body temperature and metabolic rate: one identified Adcyap1-expressing neurons in the preoptic area, the other a cluster of excitatory neurons in the anterior hypothalamus able to sustain days of hypothermia and hypometabolism. Torpor is therefore not a passive consequence of cooling but an actively regulated programme in which the brain lowers the temperature set point, and the circuitry is retained even in non-hibernators. The finding offers neural targets for medically induced hypometabolism in organ protection and critical care.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Hrvatin S 等. Neurons that regulate mouse torpor. Nature (2020) 583:115-121; Takahashi TM 等. A discrete neuronal circuit induces a hibernation-like state in rodents. Nature (2020) 583:109-114
Hrvatin S et al. Neurons that regulate mouse torpor. Nature (2020) 583:115-121; Takahashi TM et al. A discrete neuronal circuit induces a hibernation-like state in rodents. Nature (2020) 583:109-114
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1038/s41586-020-2387-5（复合著录按段核验：本标识只担保第一
#蛰伏神经环路 #下丘脑 #体温设定点 #诱导低代谢
冬眠动物如何把代谢率和体温降到极低而不受损伤？
How do hibernating animals drop metabolic rate and body temperature so low without damage?
冬眠是主动调控的过程：动物先下调代谢，代谢率可降至基础值的百分之几，体温随之接近环境温度，某些北极地松鼠腹腔温度甚至低于零度而不结冰。心率、呼吸和肾滤过大幅减慢，能量主要来自脂肪氧化并通过底物开关保存葡萄糖；同时通过抗氧化系统、蛋白合成整体抑制和细胞保护机制减少低温与复温损伤。冬眠期间还会周期性出现短暂的中途觉醒，可能用于修复代谢废物累积与免疫功能。
Hibernation is actively regulated: the animal first suppresses metabolism, sometimes to a few percent of basal rate, and body temperature then falls toward ambient, with arctic ground squirrels even holding core temperature below zero without freezing. Heart rate, breathing and renal filtration slow markedly while energy comes mainly from fat oxidation with a substrate switch that spares glucose, and antioxidant defences, global suppression of protein synthesis and cytoprotective programmes limit injury during cooling and rewarming. Periodic brief arousals interrupt torpor bouts, probably to clear accumulated metabolic costs and restore immune function.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Geiser F. Metabolic rate and body temperature reduction during hibernation and daily torpor. Annual Review of Physiology (2004) 66:239-274
Geiser F. Metabolic rate and body temperature reduction during hibernation and daily torpor. Annual Review of Physiology (2004) 66:239-274
独立核验依据 · Independent verification: 核验依据 1 DOI 10.1146/annurev.physiol.66.032102.115105
#冬眠 #代谢抑制 #蛰伏 #复温损伤
跨时区飞行和长期熬夜为什么都会带来健康代价？
Why do both transmeridian flights and chronic late nights carry health costs?
跨时区飞行使外界光照相位骤变，中枢时钟需按每天约一小时的速度重新同步，而肝脏、心脏等外周时钟的调整速度不同，出现内部去同步化，表现为困倦、消化紊乱和表现下降。长期作息与自身生物钟错位形成社会性时差，效果类似每周反复经历小幅时差，与代谢综合征、情绪障碍和心血管风险升高相关。夜班人群的流行病学研究也支持长期昼夜节律紊乱对健康有累积影响。
A flight across time zones shifts the external light phase abruptly, and the central clock re-entrains at only about an hour per day while peripheral clocks in liver and heart shift at different rates, producing internal desynchrony that shows up as sleepiness, digestive upset and reduced performance. Living on a schedule persistently offset from one's own clock creates social jetlag, which resembles repeating a small time-zone shift every week and is associated with metabolic syndrome, mood disorders and higher cardiovascular risk. Epidemiological studies of night-shift workers likewise support cumulative health effects of chronic circadian disruption.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Roenneberg T, Merrow M. The circadian clock and human health. Current Biology (2016) 26:R432-R443
Roenneberg T, Merrow M. The circadian clock and human health. Current Biology (2016) 26:R432-R443
独立核验依据 · Independent verification: 核验依据 1 DOI 10.1016/j.cub.2016.04.011
#时差 #社会性时差 #内部去同步 #夜班健康
候鸟在长距离迁徙中依靠哪些线索导航？
Which cues do migratory birds use to navigate over long distances?
候鸟同时使用多种罗盘：日间依靠太阳方位并用体内时钟校正其移动，夜间利用星空围绕天极的旋转确定方向，还能感知地磁场的倾角和强度获得方向与近似纬度信息。除罗盘外，它们借助地标、气味景观和风场做局部修正，年幼个体主要依赖遗传性的方向与时长程序，成鸟则积累了真正的地图式定位能力。多种线索互为备份，使阴天或磁扰下仍能维持航向。
Migratory birds carry several compasses at once: by day they use the sun's azimuth corrected by an internal clock, by night they read the rotation of the star field about the celestial pole, and they also sense geomagnetic inclination and intensity for direction and approximate latitude. Beyond compasses they refine their route with landmarks, olfactory landscapes and wind fields, and while juveniles rely largely on an inherited programme of direction and duration, adults acquire genuine map-based positioning. Because the cues back each other up, heading can be held under overcast skies or magnetic disturbance.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Mouritsen H. Long-distance navigation and magnetoreception in migratory animals. Nature (2018) 558:50-59
Mouritsen H. Long-distance navigation and magnetoreception in migratory animals. Nature (2018) 558:50-59
独立核验依据 · Independent verification: 核验依据 1 DOI 10.1038/s41586-018-0176-1
#迁徙 #磁感受 #太阳罗盘 #星空定向
为什么许多鸟类在迁徙季来临前会出现夜间躁动和体重激增？
Why do many birds show nocturnal restlessness and rapid weight gain before the migratory season?
这类现象由内源的年周节律驱动：即使被长期饲养在恒定光照和温度下，鸟类仍会按约一年的周期出现迁徙躁动与换羽，说明存在不依赖外界的内部日历，而光周期变化主要起校准作用。迁徙前的超量进食使体脂在数周内可翻倍，同时飞行肌增大、部分消化器官萎缩以减轻负荷。夜间躁动对应野外的夜间飞行时段，其方向偏好与该物种的实际迁徙方向一致，是研究内源迁徙程序的经典指标。
These changes are driven by an endogenous circannual rhythm: birds kept for long periods under constant light and temperature still show migratory restlessness and moult on a roughly annual cycle, revealing an internal calendar that photoperiod mainly calibrates rather than creates. Pre-migratory hyperphagia can double body fat within weeks while flight muscles enlarge and some digestive organs shrink to cut payload. The nocturnal restlessness corresponds to the night-flight window in the wild, and its directional preference matches the species' actual migratory heading, making it a classic readout of the endogenous migration programme.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Gwinner,《Circannual rhythms in birds》,Current Opinion in Neurobiology,2003 (DOI: 10.1016/j.conb.2003.10.010)
Gwinner, 'Circannual rhythms in birds', Current Opinion in Neurobiology, 2003, DOI: 10.1016/j.conb.2003.10.010
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1016/j.conb.2003.10.010
#迁徙躁动 #年周节律 #超量进食 #光周期
哺乳动物生物钟的分子基础是什么？
What is the molecular basis of the mammalian circadian clock?
核心是一个约 24 小时周期的转录-翻译负反馈环：BMAL1 与 CLOCK 形成异二聚体结合 E-box 元件，激活 Per 与 Cry 基因转录；累积的 PER 与 CRY 蛋白进入细胞核抑制 BMAL1-CLOCK 的活性，随后被 CK1 磷酸化并经泛素化降解，抑制解除后新一轮转录重启。蛋白合成、磷酸化和降解所需的时间延迟决定了周期长度，PER 磷酸化位点的突变可使人出现家族性睡眠时相提前。REV-ERB 与 ROR 构成的辅助环路稳定了振幅与相位。
At its core is a transcription-translation negative feedback loop with a period near 24 hours: BMAL1 and CLOCK heterodimerize on E-box elements to activate Per and Cry transcription, the accumulating PER and CRY proteins enter the nucleus and inhibit BMAL1-CLOCK, and they are then phosphorylated by casein kinase 1 and degraded by ubiquitination so that a new cycle can start. Delays imposed by synthesis, phosphorylation and degradation set period length, and mutations at PER phosphorylation sites cause familial advanced sleep phase in humans. An auxiliary loop of REV-ERB and ROR stabilizes amplitude and phase.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Mohawk JA, Green CB, Takahashi JS. Central and peripheral circadian clocks in mammals. Annual Review of Neuroscience (2012) 35:445-462
Mohawk JA, Green CB, Takahashi JS. Central and peripheral circadian clocks in mammals. Annual Review of Neuroscience (2012) 35:445-462
独立核验依据 · Independent verification: 核验依据 1 DOI 10.1146/annurev-neuro-060909-153128
#生物钟 #转录翻译反馈环 #BMAL1-CLOCK #周期长度