The trophoblast clock controls transport across placenta in mice

Circadian Rhythms of the Blood-Brain Barrier and Drug Delivery

The blood-brain barrier (BBB) is a critical interface separating the central nervous system from the peripheral circulation, ensuring brain homeostasis and function. Recent research has unveiled a profound connection between the BBB and circadian rhythms, the endogenous oscillations synchronizing biological processes with the 24-hour light-dark cycle. This review explores the significance of circadian rhythms in the context of BBB functions, with an emphasis on substrate passage through the BBB. Our discussion includes efflux transporters and the molecular timing mechanisms that regulate their activities. A significant focus of this review is the potential implications of chronotherapy, leveraging our knowledge of circadian rhythms for improving drug delivery to the brain. Understanding the temporal changes in BBB can lead to optimized timing of drug administration, to enhance therapeutic efficacy for neurological disorders while reducing side effects. By elucidating the interplay between circadian rhythms and drug transport across the BBB, this review offers insights into innovative therapeutic interventions.

From gestational chronodisruption to noncommunicable diseases: Pathophysiological mechanisms of programming of adult diseases, and the potential therapeutic role of melatonin

During gestation, the developing fetus relies on precise maternal circadian signals for optimal growth and preparation for extrauterine life. These signals regulate the daily delivery of oxygen, nutrients, hormones, and other biophysical factors while synchronizing fetal rhythms with the external photoperiod. However, modern lifestyle factors such as light pollution and shift work can induce gestational chronodisruption, leading to the desynchronization of maternal and fetal circadian rhythms. Such disruptions have been associated with adverse effects on cardiovascular, neurodevelopmental, metabolic, and endocrine functions in the fetus, increasing the susceptibility to noncommunicable diseases (NCDs) in adult life. This aligns with the Developmental Origins of Health and Disease theory, suggesting that early-life exposures can significantly influence health outcomes later in life. The consequences of gestational chronodisruption also extend into adulthood. Environmental factors like diet and stress can exacerbate the adverse effects of these disruptions, underscoring the importance of maintaining a healthy circadian rhythm across the lifespan to prevent NCDs and mitigate the impact of gestational chronodisruption on aging. Research efforts are currently aimed at identifying potential interventions to prevent or mitigate the effects of gestational chronodisruption. Melatonin supplementation during pregnancy emerges as a promising intervention, although further investigation is required to fully understand the precise mechanisms involved and to develop effective strategies for promoting health and preventing NCDs in individuals affected by gestational chronodisruption.

Circadian Clock-Controlled Checkpoints in the Pathogenesis of Complex Disease

The circadian clock coordinates physiology, metabolism, and behavior with the 24-h cycles of environmental light. Fundamental mechanisms of how the circadian clock regulates organ physiology and metabolism have been elucidated at a rapid speed in the past two decades. Here we review circadian networks in more than six organ systems associated with complex disease, which cluster around metabolic disorders, and seek to propose critical regulatory molecules controlled by the circadian clock (named clock-controlled checkpoints) in the pathogenesis of complex disease. These include clock-controlled checkpoints such as circadian nuclear receptors in liver and muscle tissues, chemokines and adhesion molecules in the vasculature. Although the progress is encouraging, many gaps in the mechanisms remain unaddressed. Future studies should focus on devising time-dependent strategies for drug delivery and engagement in well-characterized organs such as the liver, and elucidating fundamental circadian biology in so far less characterized organ systems, including the heart, blood, peripheral neurons, and reproductive systems.