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[A1CR]

The paper below appears to be a justification for using
water restriction vs
CRON for experiments of movement, learning, social
dominance, aggression,
etcetera, since the former strategy appears to perform well
and be less
stressful. Water-restricted mice moved more that CRed mice,
and CRed mice
also explored less that water-restricted and control mice?
Both types of
restriction appeared to enhance aggression, or acting like
hawks versus
doves. What might the percentage of Republicans versus
Democrats be among
us? Are differences in species important in the
experiments, given the
discussion in the - paper that mice appear to
demonstrate water
restriction tolerance.

Tucci V, Hardy A, Nolan PM.
A comparison of physiological and behavioural parameters in
C57BL/6J mice
undergoing food or water restriction regimes.
Behav Brain Res. 2006 Jul 24; [Epub ahead of print]
PMID: 16870275 http://tinyurl.com/runwt
Laboratory animals, when subjected to behavioural
tests, are often
motivationally primed by a period of prior water or food
restriction. To
date, it is still debatable which restriction protocol
(water versus food)
is more appropriate for different species. In general, a
protocol is
considered appropriate if animal discomfort is kept to a
minimum whilst
motivation for the task is maximised. ... We have
investigated body weight
fluctuations in three groups of C57BL/6J female mice
(water-restricted,
food-restricted and control) in two different protocols (20
h versus 22 h of
restriction per day) over 2 consecutive weeks. ... tests to
investigate
exploratory, emotional and dominance behaviours, in addition
to learning and
memory processes. Body weight fluctuations suggested that
mice tolerate a
water restriction regimen better than a comparable food
restriction regimen.
Furthermore, behavioural performances demonstrated that
food-restricted mice
show a reduction in the exploration of a new environment and
particular
aspects of their timing memories are distorted. Finally,
both water- and
food-restricted mice tended to be more offensive than
control mice when
paired with an opponent in a social dominance test condition.
... different neuroendocrinological mechanisms
regulate food and water
intake in mammals and therefore a simple equilibration of
hours of
restriction is unlikely to translate into an equivalent
level of motivation
or suffering. ... body weight fluctuation is an index of the
welfare of the
animal and, in general, the tolerated threshold implicating
a mild severity
is 80-85% of their initial ad libitum fed body weight in
both rat ... and
mouse experiments ... Are there differential responses in
the mouse to food
and water restriction schedules? Which foraging strategies
are engaged by
mice under these restriction regimes and how do they control
their
territory? Finally, how is this motivation in a conditional
learning
paradigm affected by food/water rewards following respective
restriction
regimes? By conducting a small battery of behavioural tests
in food- and
water-restricted mice, we have found that the latter are
motivated to
perform more resourcefully in a number of tasks whilst their
well-being is
only mildly affected. Such a hypothesis may have foundations
in the
evolutionary history of the mouse: it has thrived in arid
regions and
developed a physiology enabling it to survive without water
for long periods
[12]. ...
... At 8 weeks of age, mice were split into three
groups (A, B and C)
of 10 mice each. For 1 week all the animals were handled
daily to reduce the
stress impact of behavioural testing and their body weight
was monitored in
order to assess their regular fluctuations. One week later,
group A were
subjected to 2 weeks of a progressive water restriction
schedule. For the
first week (Monday-Friday) the mice were restricted for 20 h
per day and for
the second week (Monday-Friday) 22 h per day (see in [7] an
extensive
description of the restriction protocol). Group B underwent
the same
protocol but food was restricted instead of water. ... On
the last day of
the second week of restriction, 5-6 mice ... locomotor
activity (open field
test), explorative and foraging behaviour (modified Hole
Board test) and
aggressive-dominant behaviour (tube test) were assessed. ...
order of tests
was always the same for each animal. ... combination of
locomotor activity,
exploratory drive, neophobia, agoraphobia and other aspects
of anxiety or
fear in mice, as well as motor function. ... a few small
pieces of regular
food nuts or a few water drops ... social dominance tube
test measures
aggressive tendencies without allowing mice to injure one
another. Dominant
and submissive behaviours are scored for two mice during a
brief pairing in
a specialised chamber [16]. ... a dominant (winner) and a
subordinate
(loser) mouse ... classical Hawk-Dove game model ...
Conditional learning
... Control mice received either food pellets or water
randomly. In addition
to the reward-based trials, a series of probe trials (in
which no reward was
delivered) was included. These occurred randomly during each
session on an
average of one out of five trials and, importantly, it was
just these trials
that were considered for the analysis of timing learning. ...
... A restriction effect between the first week (20 h
of restriction
per day) and the second week (22 h of restriction per day),
with a mean
difference of 2.016 g. was statistically significant
(F[1,54] = 17.854; P <
0.0001). A statistically significant group effect (F[2,54] =
170.661; P <
0.0001) between water-restricted, food-restricted and
control mice was
found. In Fig. 2, we observed that during the 20 h
restriction period, the
body weight in both water and food-restricted mice was fully
recovered after
the free water/food access period per day (the peak of the
mean differences
was always a positive value). In contrast during the 22 h
restriction, the
food-restricted group showed a gradual declining effect of
the weight peak
after the free food access period. Moreover, in both weeks,
the body weight
minima in the water-restricted group were progressively less
severe, whereas
those in the food-restricted group were progressively worse.
These results
suggest that a gradual adaptation mechanism to the water
restriction was
ongoing in water-restricted mice, making the recovery period
more efficient.
On the contrary, food-deprived mice accumulated the
difficulties to maintain
a food-restricted regimen and their recovery period did not
compensate the
cost of the restriction. Nevertheless, the intensive
monitoring of animal
weights over this 2-week period indicated that body weight of
food-restricted mice rarely fell below 85% of free-fed
weight throughout the
course of the experiment. Moreover, no further weight-loss
was reported with
a continuation of the restriction over an additional 15
working days. This
would indicate that the food-restricted mice do adapt
eventually to a 22 h.
restriction schedule but that the adaptation time takes
longer than with
water-restriction. The observation of the natural body
weight fluctuations
in control mice showed a circadian rhythm, increasing during
the dark phase
and decreasing during the light phase. The latter
observation in
unrestricted mice could be related to the fact that the
mouse is a nocturnal
species, dedicating more time for feeding during the dark
phase of the
light/dark cycle.
... We observed no sign of distress during the first
week in any of the
three groups of mice. During the second week,
food-restricted mice showed a
mild reduction of activity ... Open field The examination of
the motor
activity in the centre and at the periphery of the open
field revealed no
different pattern of exploration between food-restricted,
water-restricted
and control mice in almost all of the parameters recorded
(see Table 1).

Table 1. Statistical analysis of group interactions
within OF and mHB
tests
=====================================================
Water-restricted Food-restricted Controls Degrees of
freedom (d.f.)
Fisher (F) Significance (P)
N Mean S.E. Mean S.E. Mean S.E.
=====================================================
Open field---------------------------------
Distance moved (cm) 6 38.2 2.7 38.9 2.7 37.6 16.0 2 0.06 0.94
Velocity (cm/s) 6 6.4 0.5 6.5 0.5 6.3 0.3 2 0.06 0.94
Heading (°) 6 284.3 11.8 207.3 32.3 192.3 20.5 2 4.56 0.03^*
Turn angle (total degrees) 6 318074.8 3823.7 302151.1
6103.5 310810.4
4853.8 2 2.53 0.11
Angular velocity (°/s) 6 ?194.8 12.0 ?169.2 11.6 ?191.1
11.5 2 1.40 0.28
Movements (total) 6 467.0 14.8 467.1 14.6 464.9 14.2 2
0.01 0.99
Movements (%) 6 77.8 2.5 77.9 2.4 77.5 2.4 2 0.01 0.99
Rearing frequencies 6 53.8 5.4 51.3 9.7 41.8 3.9 2 0.87 0.44
mHB------------------------------------
Distance moved (cm) 5 42.5 2.4 24.9 4.2 38.3 2.0 2 8.87
0.004^*
Velocity (cm/s) 5 7.1 0.4 4.2 0.7 6.4 0.3 2 8.87 0.004^*
Heading (°) 5 252.4 28.7 154.8 25.3 206.2 37.8 2 2.47 0.126
Turn angle (total degrees) 5 263973 9515.1 269496.6 5.0
269378.7 4421.2 2
0.12 0.888
Angular velocity (°/s) 5 ?126.7 16.4 ?293.0 86.4 ?154.1
12.5 2 3.02 0.087
Movements (total) 5 495.0 8.9 355.3 46.9 480.1 14.8 2 7.07
0.009^*
Movements (%) 5 82.5 1.5 59.2 7.8 80.0 2.5 2 7.07 0.009^*
Rearing frequencies 5 10.0 4.2 3.8 0.9 4.0 0.8 2 1.95 0.185
=====================================================
The following parameters have been calculated by video
track system: the
distance travelled by the centre of gravity of the mouse
within the area
(distance moved); the speed of the mouse (velocity), that
is, the distance
moved per unit time; the direction of movement in relation
to a reference
direction (heading), with 0° referring to the top of the
image on the
computer; the change in direction of the movement of the
mouse between two
consecutive locations in the arena (turn angle); the change
in direction of
movement of the mouse per unit time (angular velocity); the
total movements
and the percentage of movement within the session; vertical
activity
(rearing).
Significant p values are indicated [*].

... mHB test ... A number of motor activity parameters
which were not
significantly different within the OF test, were significant
in the mHB test
(see Table 1). The mHB test revealed that the
food-restricted mice were less
explorative of the new environment. Moving time accounts for
just 59.2%
(±7.8) of the time in the arena compared to 82.5% (±1.48)
and 80% (±2.4) for
the water-restricted and control mice, respectively.
Furthermore,
food-restricted mice differed from the other two groups in
centre activity.
In particular, the velocity at the centre was significantly
lower in
food-restricted mice (F[2,12] = 8.87; P = 0.004). As well as
showing an
increase in arena activity, the water-restricted mice
explored the holes on
the floor of the arena with a mean duration of 62.9 s
(±5.57) within the
session compared to 21.3 (±6.6) and 37.9 (±4.5) for the
food-restricted and
control mice, respectively. Taken together, the mHB results
indicated a
different behavioural profile in the arena that was
dependent on the type of
restriction: water-restricted mice moved across the arena
the same as the
control mice, but they explored the holes more.
Food-restricted mice showed
a reduction in both exploration and activity.
... Social dominance tube test ... Social dominance,
as measured by the
tube test, was assessed by summarizing the number of matches
in which each
group was dominant. Rates of dominant and submissive
behaviours between
groups analyzed within a contingency table were not
statistically
significant (Chi-square = 1.79, P = NS). Control mice won
38.4% of the time,
more than the food-restricted mice (34.4%) which in turn won
more than the
water-restricted mice (30%). These results, so scored,
failed to demonstrate
a difference in dominance between the groups. However, the
analysis of Hawk
and Dove behaviours between the experimentally selected mice
and their
opponents, resulted in significant differences within a
table of contingency
for Hawk and Dove occurrences (water-restricted group:
Chi-square = 9.067, P
< 0.05; food-restricted group: Chi-square = 12.483, P <
0.001; controls:
Chi-square = 18.631, P < 0.001). In particular, control mice
behaved as
Hawks only 24% of the time, while food and water-restricted
mice behaved as
Hawks on 34 and 36% of the time, respectively. Thus,
although no group
showed a particular dominance rate in comparison to the
other groups,
restricted mice tended to assume an aggressive position with
a higher
frequency, compared to controls, when confronted with an
opponent.
... Conditional learning ... The total nose poking
behaviour over the
entire training period revealed a main significant group
effect (F[2,36] =
42.6; P < 0.0001), a phase effect (F[2,36] = 61.6; P <
0.0001) and a group ×
phase interaction effect (F[4,36] = 19.05; P < 0.0001).
Food-restricted mice
did show a significantly higher number of nose pokes at the
post-[conditional stimulus (CS)] phase compared to
water-restricted mice and
controls (Scheffé, P < 0.001 and P < 0.001, respectively).
However, nose
poking was not restricted to the post-CS phase as this was
also higher than
other groups during the CS phase (Scheffé, P < 0.05),
indicating a combined
effect of learning and anticipatory activity. The
performance of
water-restricted mice was more temporally refined. Fig. 3
shows that, from
day 10 (panel C), water-restricted mice showed an increased
number of
responses during the post-CS relative to the CS and
[background (BK)] time
windows, while food-restricted mice maintained high
responses over CS and
BK. This observation suggests that water-restricted mice
managed to refine
the timing of nose pokes from day 10. The differential
allocation of nose
poking behaviour to both CS and post-CS time windows was
considered to be an
index of anticipatory and retroactive responses. In this
respect,
water-restricted mice considered nose poking during the
post-CS phase to be
more advantageous than during the CS. Control mice show no
increase
throughout training. Cumulative nose pokes for each session,
analysed for
all the training sessions by repeated ANOVA, showed a
significant effect
between water-restricted and food-restricted mice (mean
difference = ?7.650,
P < 0.05) and between food-restricted mice and controls
(mean difference =
5.849, P < 0.05), while water-restricted versus control mice
differences
were not statistically significant (mean difference =
?1.801, P < NS). In
terms of learning and memory processes, the results plotted
in Fig. 3 show
that both water-restricted and food-restricted mice learnt
to make an
economically correct choice, increasing the nose pokes
during the
significant time windows (CS and post-CS), as shown at days
10 and 15. At
day 15, both water-restricted and food-restricted mice
refined their nose
poking timing but while water-restricted mice showed a
significant increase
in nose pokes during post-CS alone, food-restricted mice
also showed a
significantly higher mean number of nose pokes during CS
relative to BK
(Scheffé, P < 0.0001). Although there is still a significant
indication of
learning in food-restricted mice, the increased number of
nose pokes over
all the time windows, including the significant CS/post-CS
time windows, is
an economically disadvantageous behaviour. Conversely, the
specific increase
in post-CS nose pokes, shown by water-restricted mice, is a
robust index of
a refined timed response.
... Values for both locomotor activity (e.g.
percentage of moving time
within the arena) and exploration (e.g. exploration of the
holes) in
food-restricted mice demonstrated a lack of motivation to
explore the new
environment. ... to adapt the tube test to the Hawk-Dove
game, the
competition started when the two mice met at the centre of
the tube. Each
animal had to make a decision: whether to escalate the
conflict (to fight
for the territory) or to retreat (to give up the territory
without a fight).
The rationale behind this conflict is that individuals who
hold territories
have a greater fitness [22]. Maynard Smith hypothesized that
when the
territory is associated with a high benefit and injury with
low cost,
animals genetically disposed to behave as Hawks are
favourite and vice
versa. If both benefit and costs are high, then an
evolutionary stable
strategy for that species shows up within a fixed
probability of playing as
a Hawk or as a Dove. ...

water-restricted mice maximized such an efficiency using a
particular
strategy: they increased levels of exploration without
spending more energy
in an augmentation of locomotor activity. On the other hand,
food-restricted
mice reduced both locomotor activity and exploration; in
doing so, they just
reduced their chances of finding food. ... water-restricted
mice show a
better understanding of reward-timing since their timed
behaviour was
concentrated within one time window compared to that of
food-restricted mice
which was distributed over two time windows. ... water
restriction would
appear to promote explorative and cognitive performance
while limiting
emotional confounds. Finally, our results show that the
reduction of body
weight in water-restricted mice is moderate and does not
compromise the
welfare of the animals.