Sunday, April 5, 2009

Adverse metabolic and cardiovascular consequences of not maintaining circadian rythm

The following studies signify the importance of maintaining a regular routine of sleeping, eating and other daily activities.
In a recent study, Ciprian and colleagues found increased pathological remodeling and vascular injury in mice with aberrant circadian rhythms, Bmal1-knockout and Clock mutant. In addition, naive aortas from Bmal1-knockout and Clock mutant mice exhibit endothelial dysfunction. Akt and subsequent nitric oxide signaling, a pathway critical to vascular function, was significantly attenuated in arteries from Bmal1-knockout mice. The authors concluded that their data reveal a new role for the circadian clock during chronic vascular responses that may be of significance in the progression of vascular disease.
In another study by Scheer et at, Ten adults (5 female) underwent a 10-day laboratory protocol, wherein subjects ate and slept at all phases of the circadian cycle—achieved by scheduling a recurring 28-h “day.” Subjects ate 4 isocaloric meals each 28-h “day.” For 8 days, plasma leptin, insulin, glucose, and cortisol were measured hourly, urinary catecholamines 2 hourly (totaling ≈1,000 assays/subject), and blood pressure, heart rate, cardiac vagal modulation, oxygen consumption, respiratory exchange ratio, and polysomnographic sleep daily. Core body temperature was recorded continuously for 10 days to assess circadian phase. Circadian misalignment, when subjects ate and slept ≈12 h out of phase from their habitual times, systematically decreased leptin (−17%, P <>P <>P = 0.006), completely reversed the daily cortisol rhythm (P <>P = 0.001), and reduced sleep efficiency (−20%, P <0.002).>
Vascular Disease in Mice With a Dysfunctional Circadian Clock
Ciprian B. Anea, MD; Maoxiang Zhang, PhD; David W. Stepp, PhD; G. Bryan Simkins, BS; Guy Reed, MD; David J. Fulton, PhD; R. Daniel Rudic, PhD
From the Department of Pharmacology and Toxicology (C.B.A., M.Z., G.B.S., D.J.F., R.D.R.), Department of Physiology (D.W.S.), Vascular Biology Center (D.W.S., D.J.F.), and Cardiology Division, Department of Medicine (G.R.), Medical College of Georgia, Augusta.
Circulation. 2009;119:1510-1517
Published online before print March 9, 2009, doi: 10.1161/CIRCULATIONAHA.108.827477
Adverse metabolic and cardiovascular consequences of circadian misalignment
Frank A. J. L. Scheer, Michael F. Hilton, Christos S. Mantzoros, and Steven A Shea
Division of Sleep Medicine, Brigham and Women's Hospital, Boston, MA 02115
Harvard Medical School, Harvard University, Boston, MA 02115; and
Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215
Published online before print March 2, 2009, doi: 10.1073/pnas.0808180106
PNAS March 17, 2009 vol. 106 no. 11 4453-4458

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