Cross fostering in mice: Behavioral and physiological carry-over effects in adulthood

University of Milan, Milano, Lombardy, Italy
Genes Brain and Behavior (Impact Factor: 3.66). 05/2004; 3(2):115-22. DOI: 10.1111/j.1601-183X.2003.00059.x
Source: PubMed


Cross fostering is a widely used laboratory practice. However, relatively few studies have directly investigated the carry-over effects of this procedure in adult animals. The aim of the present study is to investigate the late effects of cross fostering (CF) at birth (in litters composed of no siblings) on adult mice. When adults, cross-fostered male and female mice were examined for intrasex aggression, and levels of emotionality, exploration and anxiety. In addition, body weight was monitored, several internal organs were weighed and plasma corticosterone levels were measured. When compared to controls, body weight of CF male and female mice was increased, at least after early puberty. CF males showed smaller preputial glands, while basal corticosterone level was not affected by cross fostering. In the free-exploratory test, CF males, but not females, showed a behavioral profile suggestive of lower anxiety. These effects in adulthood cannot be ascribed to differences in the maternal care received, which was not affected by cross fostering. In conclusion, cross fostering at birth induced a number of behavioral and physiological alterations in mice, particularly in males. These findings should be carefully evaluated when applying cross fostering procedure to laboratory animals.

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    • "Rare findings suggest that cross fostering is not innocuous, because the procedure for group formation, which involves housing of unfamiliar and unisexual subjects, can be stressful [88]. For example, in mice, cross fostering is linked with reduced growth and altered behaviours [88] [89] [90], while in rats, cross fostering alters nociception and emotional behaviour [91] [92]. Furthermore, cross fostering per se influences cardiovascular and metabolic function in adulthood, programming a 'thrifty' phenotype , especially in male mice [93]. "
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