. 2010 Jun 10;299(3):R728–R739. doi: 10.1152/ajpregu.00837.2009

Table 3.

Diurnal variation in core body temperature and ambulatory activity in rats fed a control (0.86% methionine) or methionine-restricted diet (0.17% methionine) ad libitum for 6, 12, or 20 mo

		Core Body Temperature (°C ± SE)	Ambulatory Activity (Beam Breaks ± SE)
Dietary Treatment	Time on Diet	Night (11 PM–1 AM)	Day (7 AM–7 PM)	Night (7 PM–7 AM)
Control	6 mo	35.4 ± 0.28^a
MR		37.0 ± 0.25^b
Control	12 mo	35.2 ± 0.18^a
MR		36.0 ± 0.19^b
Control	20 mo	36.1 ± 0.19^a	2271 ± 121^a	5500 ± 120^a
MR		35.5 ± 0.20^a	1579 ± 67^b	6300 ± 270^a

Representative 32 day-old male Fischer 344 rats were randomly assigned to receive a control diet containing 0.86% methionine or a diet with methionine restricted to 0.17% (MR). The diets were provided ad libitum, and cohorts of each group consumed their respective diets for 6, 12, or 20 mo. After 6, 12, and 20 mo on the respective diets, core body temperature was measured at 30-min intervals between 1 and 3 PM (day) and between 11 PM and 1 AM (night), as described in materials and methods. Daytime body temperatures averaged 34.0 ± 0.12°C and did not differ among groups or change with age. Mean body temperatures during the night were compared by one-way ANOVA. ^a,b Means having a different letter superscript within each age differ at P < 0.05. After 20 mo on the respective diets, voluntary ambulatory activity was measured in their home cages for three distinct 4-day periods for rats in each group as described in materials and methods. Voluntary activity was expressed as beam breaks per hour and mean daytime and nighttime beam breaks were analyzed by ANOVA. ^a,b Means with a different letter superscript within each time of day differ at P < 0.05.