Abstract
Much of the research done on aging, oxidative stress, anxiety, and cognitive and social behavior in rodents has focused on caloric restriction (CR). This often involves several days of single housing, which can cause numerous logistical problems, as well as cognitive and social dysfunctions. Previous results in our laboratory showed the viability of long-term CR in grouped rats. Our research has studied the possibility of CR in grouped female and male littermates and unrelated CB6F1/J (C57BL/6J × BALBc/J hybrid strain) mice, measuring: (i) possible differences in body mass proportions between mice in ad libitum and CR conditions (at 70% of ad libitum), (ii) aggressive behavior, using the number of pushes and chasing behavior time as an indicator and social behavior using the time under the feeder as indicator, and (iii) difference in serum adrenocorticotropic hormone (ACTH) concentrations (stress biomarker), under ad libitum and CR conditions. Results showed the impossibility of implementing CR in unrelated male mice. In all other groups, CR was possible, with a less aggressive behavior (measured only with the number of pushes) observed in the unrelated female mice under CR conditions. In that sense, the ACTH levels measured on the last day of CR showed no difference in stress levels. These results indicate that implementantion of long-term CR in mice can be optimized technically and also related to their well-being by grouping animals, in particular, related mice.
Highlights
Caloric restriction (CR) has been widely used in experimental research [1, 2]
The experimental subjects came from a 10 monogamous breeding pairs, in which the offspring were separated into groups of three after weaning in separate cages into males and females of the same litter, with ad libitum feeding for the littermate groups
There was fierce fighting between animals, with blood and several skin injuries. This forced us to apply the ethical protocol and, as was mentioned above under Method, the nine animals of the group Restricted unrelated males were discarded from the experiment and CR was interrupted to avoid further fighting and possible injuries to mice
Summary
CR has been used in different modalities (moderate, 70–80% and intense restriction, 50–60%), with respect to the maximum ad libitum (AL) intake It is proposed as a maintenance method between 6 and 24 months or more [3]. CR has been studied in relation to oxidative stress, where it was found to have an antioxidant effect [10], or in relation to the reduction of inflammatory processes induced by aging and measured in microglia levels [11]. Another context in which CR has been studied is anxiety. CR has positive effects, such as heightened social behavior between mice [18]
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