Abstract:
Circadian, metabolic, and reproductive systems are inter-regulated. Excessive fatness and
circadian disruption alter normal physiology and the endocrine milieu, including cortisol, the
primary stress hormone. Our aim was to determine the effect feeding a high fat diet to
female ICR mice had on diurnal feeding pattern, weight gain, body composition, hair corticosterone levels and circadian patterns of fecal corticosterone. Prepubertal (~35d of age) ICR
mice were assigned to control (CON; 10% fat) or high fat (HF; 60% fat) diet and fed for 4 wk
to achieve obesity under 12h light and 12h of dark. Feed intake was measured twice daily to
determine diurnal intake. Mice were weighed weekly. After 4 wk on diets hair was collected
to measure corticosterone, crown-rump length was measured to calculate body mass index
(BMI), and body composition was measured with EchoMRI to determine percent fat. HF
mice weighed more (P<0.05) after week two, BMI and percent body fat was greater
(P<0.05) in HF than CON at the end of wk 4. HF mice consumed more during the day
(P<0.05) than CON mice after 1 week on diets. Hair corticosterone was higher in HF mice
than in CON (P<0.05). Fecal circadian sampling over 48hr demonstrated that HF mice had
elevated basal corticosterone, attenuated circadian rhythms, and a shift in amplitude. High
fat feeding for diet induced obesity alters circadian eating pattern and corticosterone
rhythms, indicating a need to consider the impact of circadian system disruption on reproductive competence.
