Specific role of dietary fat in modifying cardiovascular and locomotor activity 24-h rhythms. (June 2015)

• Record Type: Journal Article
• Authors: Barzel, Benjamin; Lim, Kyungjoon; Burke, Sandra L.; Armitage, James A.; Head, Geoffrey A.
• Is Part Of: Chronobiology international. Volume 32:Number 5(2015)
• Page Start: 668
• Page End: 676
• Publication Date: 2015-06
• Subjects: Chronobiology -- Periodicals; Biological rhythms -- Periodicals; Circadian rhythms -- Periodicals; 571.77
• DOI: 10.3109/07420528.2015.1032414
• Languages: English
• ISSNs: 0742-0528

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <p>Meal-fed conscious rabbits normally exhibit postprandial elevation in blood pressure, heart rate (HR) and locomotor activity, which is abolished by consumption of a high-fat diet (HFD). Here, we assessed whether the cardiovascular changes are attributable to the increased caloric intake due to greater fat content or to hyperphagia. Rabbits were meal-fed during the baseline period then maintained on either an <italic>ad libitum</italic> normal fat diet (NFD) or <italic>ad libitum</italic> HFD for 2 weeks. Blood pressure, HR and locomotor activity were measured daily by radio-telemetry alongside food intake and body weight. Caloric intake in rabbits given a NFD <italic>ad libitum</italic> rose 50% from baseline but there were no changes in cardiovascular parameters. By contrast, HR increased by 10% on the first day of the <italic>ad libitum</italic> HFD (<italic>p</italic> < 0.001) prior to any change in body weight while blood pressure increased 7% after 4 d (<italic>p</italic> < 0.01) and remained elevated. Baseline 24-h patterns of blood pressure and HR were closely associated with mealtime, characterised by afternoon peaks and morning troughs. When the NFD was changed from meal-fed to <italic>ad libitum</italic>, blood pressure and HR did not change but afternoon activity levels decreased (<italic>p</italic> < 0.05). By contrast, after 13 d <italic>ad libitum</italic> HFD, morning HR, blood pressure and activity increased by 20%, 8% and 71%, respectively. Increased caloric intake specifically from fat, but not as a result of hyperphagia, appears to directly modulate cardiovascular homeostasis and circadian patterns, independent of white adipose tissue accumulation.</p> </abstract>