January 29, 2011

Some Noise About Internal Alarm Clocks

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Joseph V. Madia, MD By:

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Researchers discover mechanism that makes internal alarm (circadian rhythm) clocks tick

(dailyRx News) Shifts and disruption in internal alarm clocks (known as the circadian clock) caused by shift work and erratic sleep patterns can contribute to cancer, diabetes and depression, among other health problems.

Now researchers from Britain's Cambridge and Edinburgh universities have identified the mechanism that controls this clock in all life forms, which may point to better therapies and preventive treatments for certain diseases. The findings hold important implications for those who do shift work, such as nurses and pilots.

The study suggests the circadian clock is the same in humans as it is in algae and has existed for millions of years.

Researchers also found that red blood cells have a 24-hour rhythm, a significant discovery because circadian rhythms have always been assumed to be linked to DNA (which red blood cells do not have).

By furthering their knowledge of how the circadian clock in cells works, Akhilesh Reddy, who led the first of two studies, said researchers hope to make the links that bind these clocks to diabetes, cancer and bipolar disorder, among other diseases, more clear.

For the study, researchers used experimental drugs to reset circadian clocks in mice, opening up the possibility that drugs might in future be developed to restore normal rhythms in humans. They examined levels of biochemical markers and found a pattern modification in proteins known as peroxiredoxins that went back and forth over 24 hours, which controls the clock.

Andrew Millar of Edinburgh University, who led the second study, said circadian clocks "must be far more important and sophisticated than we previously realized," adding more research is needed to determine how and why the clocks developed, and the role they play in regulating and controlling bodies.

Depression impacts an estimated 15 million adults in the United States. Depression is a state of prolonged low mood and aversion to activity. A person's thoughts, behavior, feelings and physical well-being are affected and may include feelings of sadness, anxiety, emptiness, hopelessness, worthlessness, guilt, irritability, or restlessness. The primary treatments for major depression are psychological counseling and medications. Medication therapies include selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), norepinephrine and dopamine reuptake inhibitors (NDRIs). SSRIs include: fluoxetine (Prozac®), paroxetine (Paxil®), sertraline (Zoloft®), citalopram (Celexa®) and escitalopram (Lexapro®). SNRIs include: duloxetine (Cymbalta®), venlafaxine (Effexor®) and desvenlafaxine (Pristiq®). Bupropion (Wellbutrin) is an NDRI. Atypical antidepressants include trazodone (Desyrel®) and mirtazapine (Remeron®). Each medication category has different side effects.

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Reviewed by: 
Joseph V. Madia, MD
Review Date: 
January 28, 2011

Last Updated:
March 9, 2011