First published online June 27, 2008
Journal of Experimental Biology 211, 2214-2223 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.017525
Female mice respond differently to costly foraging versus food restriction
Kristin A. Schubert1,*,
Lobke M. Vaanholt1,2,
Fanny Stavasius1,
Gregory E. Demas3,
Serge Daan1 and
G. Henk Visser1,4,
1 Department of Behavioral Biology, Center for Behavior and Neurosciences,
University of Groningen, Kerklaan 30, 9751 NN, The Netherlands
2 Aberdeen Centre for Energy Regulation and Obesity (ACERO), Aberdeen, UK
3 Center for the Integrative Study of Animal Behavior, Indiana University,
Bloomington, IN, USA
4 Centre for Isotope Research, University of Groningen, The Netherlands
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Fig. 1. Development of wheel-running activity (revs day–1 and km
day–1), energy intake (kJ day–1) and whole
body mass (g) of females mice facing low foraging costs (L; filled circles),
high foraging costs (H; open circles) and restricted feeding without foraging
effort (R; gray shading). Error bars show the standard error of the mean.
Temperature transmitters were surgically implanted (S) on day
–34±1. L and H females were placed in cages with running wheels
on day –27 and exposed to the foraging task on day 0. Food rationing of
R females also began on day 0. Foraging costs of H mice increased by 10% of
baseline every other day until day 20 and were then held constant (at 200%
baseline). Animals were injected with the novel antigen KLH on day 39±1
and sacrificed on day 49±1. Energy intake is based on grams of food
ingested and manufacturer's estimate of energy content of food (line 3 of
Table 1). Sample sizes per
group were L=8, H=6 and R=7.
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Fig. 2. Wheel-running activity (revs day–1 and km
day–1) in relation to workload during the workload phase.
Filled circles represent mice facing low foraging costs (individual baseline),
and open circles represent mice facing high foraging costs (2x
individual baseline). Iso-reward lines show the activity required under
different reward rates to obtain a constant amount of food (100% line) double
intake (200% line) or reduce intake by half (50% line), ignoring cost of
transport. Sample sizes per group were L=8, H=6 and R=7.
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Fig. 3. Circadian rhythm of wheel-running behavior of female mice facing low (L;
filled symbols) and high (H; open symbols) foraging costs. Hourly activity
averaged over days 21 to 27 of the workload phase showed no differences
between groups (for all, P>0.1). Sample sizes per group were L=8,
H=6 and R=7.
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Fig. 4. Relationship between body mass and metabolism during the workload phase.
Triangles represent resting metabolic rate (RMR), and circles represent daily
energy expenditure (DEE). Body mass significantly predicted both DEE (solid
line: F1,16=26.3, P<0.0001,
R2=0.62; y=2.25x–12.41) and RMR
(dotted line: F1,16=8.3, P=0.01,
R2=0.34; y=0.80x+10.21) of mice faced
with low foraging costs (black symbols), high foraging costs (open symbols),
or food restriction without foraging (grey symbols). Sample sizes per group
were L=7, H=6 and R=5.
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Fig. 5. Serum IgG antibody production in response to the novel antigen, KLH. Tail
blood samples were collected 10 days after injection. Mean values are given
for female mice under low foraging costs (L), high foraging costs (H), and
food restriction without foraging (R). Sample sizes are L=8, H=6 and R=7; bars
represent s.e.m.
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© The Company of Biologists Ltd 2008
