29 Mar As We Age, Our Circadian Clock Becomes Less Sensitive To Light, Leading To Sleep Problems

MedicalResearch.com Interview with:
Dr Gurprit S. Lall BSc, MSc, PhD, PGCHE, FHEA
Medway School of Pharmacy
Interim Deputy Head of School
Senior Lecturer in Pharmacology
Director of Graduate Studies (Research),
University of Kent at Medway
Chatham Maritime, Chatham, Kent

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Medical advancement in prevention and diagnosis of disease has increased life expectancy significantly, thus generating an ageing population far greater than previously seen.  Because of this, it is essential that we begin to understand the ageing process, together with the health implications associated with senescence.  Recent research has found that changes in the circadian clock, located in the brain, play a contributing role in the decline of many physiological and behavioural traits observed through the ageing process.  One example of this, which is commonly seen in the elderly is a decline in sleep-wake cycle regulation; typically presenting as disrupted sleeping patterns.

The circadian clock, in mammals, possesses the ability to integrate our social lifestyle choices with the environmental day-night cycle to generate a 24-hour rhythm to which our physiological functions are synchronised.  It is this synchronisation that plays a vital role in regulating many of our behavioural outputs, such as sleeping-wake patterns.  This clock takes its strongest timing cue from the natural day night cycle governed by the duration of daily sunlight.

Our study investigated the changes in the interpretation of this light signal by the circadian clock as we age and its impact on function.  We found that the clock became less responsive to light stimuli at both the level of clock cells and at driving behavioural activity.  We were able to narrow this down to changes in the proteins within cells that relay light information to the molecular time setting machinery.  In detail, light signals are relayed to the clock through an excitatory neurotransmitter called glutamate and this signal is predominantly relayed through NMDA receptors located on the surface of clock cells.  It is the configuration of the NMDA receptor that alters as we age and this leads to the clock becoming less responsive to light.

MedicalResearch.com: What should readers take away from your report?

Response: Our report is the first to show that the way in which mammals perceive light for circadian entrainment alters as they age.  Mammals become less responsive to light due to structural changes in key proteins that drive the core clock setting mechanisms that ultimately allow us to set our daily behavioural routines.

MedicalResearch.com: What recommendations do you have for future research as a result of this work?

Response: Our study gives an insight into the natural ageing process and the changes that occur within the circadian system because of it.  For future research, there is scope for investigation into novel drug therapies centred on our findings.  In addition, there may be possible avenues in redefining light stimuli to take into account the alterations in cellular dynamics due to the changes in the NMDA receptor structure, with an aim to optimising signalling in the aged circadian clock. 

MedicalResearch.com: Is there anything else you would like to add?

Response: Medical advancement and our understanding of healthy living has revolutionised society.  The resulting increase in life expectancy presents us with an every-growing ageing population; thus research into the ageing process is essential in order to continue to provide optimal care at all stages of life.

There are no disclosers to report.

Citations:

S.M. Biello, D.R. Bonsall, L.A. Atkinson, P.C. Molyneux, M.E. Harrington, G.S. Lall. Alterations in glutamatergic signalling contribute to the decline of circadian photoentrainment in aged mice.. Neurobiology of Aging, 2018; DOI: 10.1016/j.neurobiolaging.2018.02.013

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Last Updated on March 29, 2018 by Marie Benz MD FAAD