Energy expenditure and locomotor activity in mice selected for food intake adjusted for body weight

Abstract

The aim of this study was to examine the differences in physical activity and their contribution to differences in energy utilization in mice, selected either high or low for food intake, adjusted for body weight, which show correlated responses in lean content and metabolic rate. Simultaneous measurements of fasting metabolic rate and activity were made in lines of mice selected at either: a young age, 4-to 6-week food intake corrected for 4-week body weight; or an older age, 8- to 10-week food intake corrected for mean weight at 8 and 10 weeks of age. Correlated response in metabolic rate was found to have been accompanied by changes in locomotor activity near the ages at selection in both sets of lines. Activity, however, accounted for only a small proportion of variation in fasting heat production, generally less than 5%, although a highly positive correlation (r=0.63) between the two traits was found. It was concluded that selection for food intake adjusted for body weight has led to correlated response in physical activity. In consequence, mice selected in the upward direction expend some of the excess energy intake rather than assimilating it as body mass and are, therefore, slightly leaner than their counterparts selected in the downward direction.

Locomotor activity, core body temperature, and circadian rhythms in mice selected for high or low heat loss.

“…Few studies evaluated both sexes for activity level, and of those that did, even fewer included it as an effect in their model. Moruppa (1990) found that male mice were more active than females at young (3-to 4-wk) and old (10-to 11-wk) ages. This is contrary to our findings, but Moruppa (1990) measured for only a 3-h period during the lighted part of the day.…”

“…Moruppa (1990) found that male mice were more active than females at young (3-to 4-wk) and old (10-to 11-wk) ages. This is contrary to our findings, but Moruppa (1990) measured for only a 3-h period during the lighted part of the day. However, cattle data reported by Voisinet et al (1997) agree with this study; heifers were more active (temperamental) than steers.…”

“…Dauncey (1986) found that C57BL ob/ ob mice were less active compared with lean C57BL 6/ 6 mice. Mice, selected for appetite or maintenance were found to have different activity level by Moruppa et al (1990) during daylight hours. Differences in daily amplitude oscillations of locomotor activity were found in C57BL/6 compared with BALB/cBy strains of mice (Toth et al, 1995).…”

“…Activity is positively correlated with heat loss (Moruppa, 1990), feed intake (Voisinet et al, 1997), and core body temperature (Gordon, 1993). Genetic selection of mice in our laboratory (Nielsen et al, 1997a,b) resulted in significant changes in heat loss and feed intake.…”

“…Activity plays a significant role in the energy expenditure of cattle (Nienaber et al, 1985), swine (Halter et al, 1980;Verstegen et al, 1982;Henken et al, 1991), poultry (MacLeod et al, 1982;Luiting et al,1991), and mice (Daucey, 1986;Moruppa, 1990;Bunger et al, 1998). Activity is positively correlated with heat loss (Moruppa, 1990), feed intake (Voisinet et al, 1997), and core body temperature (Gordon, 1993).…”