Chronic exposure to stress hormones, whether it occurs during the prenatal period, infancy, childhood, adolescence, adulthood or aging, has an impact on brain structures involved in cognition and mental health. However, the specific effects on the brain, behaviour and cognition emerge as a function of the timing and the duration of the exposure, and some also depend on the interaction between gene effects and previous exposure to environmental adversity. Advances in animal and human studies have made it possible to synthesize these findings, and in this Review a model is developed to explain why different disorders emerge in individuals exposed to stress at different times in their lives.

Effects of stress throughout the lifespan on the brain, behaviour and cognition

Time in the biological sense is measured by cycles that range from milliseconds to years. Circadian rhythms, which measure time on a scale of 24 h, are generated by one of the most ubiquitous and well-studied timing systems. At the core of this timing mechanism is an intricate molecular mechanism that ticks away in many different tissues throughout the body. However, these independent rhythms are tamed by a master clock in the brain, which coordinates tissue-specific rhythms according to light input it receives from the outside world.

Coordination of circadian timing in mammals

Molecular Bases for Circadian Clocks

https://www.cell.com/cell/pdf/S0092-8674(00)81965-0.pdf

The Sleep Disorder Canine Narcolepsy Is Caused by a Mutation in the Hypocretin (Orexin) Receptor 2 Gene

The CLOCK transcription factor is a key component of the molecular circadian clock within pacemaker neurons of the hypothalamic suprachiasmatic nucleus. We found that homozygous Clock mutant mice have a greatly attenuated diurnal feeding rhythm, are hyperphagic and obese, and develop a metabolic syndrome of hyperleptinemia, hyperlipidemia, hepatic steatosis, hyperglycemia, and hypoinsulinemia. Expression of transcripts encoding selected hypothalamic peptides associated with energy balance was attenuated in the Clock mutant mice. These results suggest that the circadian clock gene network plays an important role in mammalian energy balance.

/pdf/obesity-and-metabolic-syndrome-in-circadian-clock-mutant-23ry2o2pmn.pdf

Obesity and Metabolic Syndrome in Circadian Clock Mutant Mice

https://www.cell.com/cell/pdf/S0092-8674(00)80245-7.pdf

Positional cloning of the mouse circadian clock gene.

https://www.cell.com/cell/pdf/S0092-8674(00)80246-9.pdf

Yaliang Zhao

Papers

Positional cloning of the mouse circadian clock gene.

Functional Identification of the Mouse Circadian Clock Gene by Transgenic BAC Rescue

Molecular cloning and characterization of the human CLOCK gene: expression in the suprachiasmatic nuclei.