Effects of leptin infusion during peak lactation on food intake, body composition, litter growth, and maternal neuroendocrine status in female Brandt's voles (Lasiopodomys brandtii)

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SUMMARYLimits to sustained energy intake (SusEI) are important because they constrain many aspects of animal performance. Individual variability in SusEI may be imposed by genetic factors that are inherited from parents to offspring. Here, we investigated heritability of reproductive performance in MF1 mice. Food intake, milk energy output (MEO) and litter mass were measured in mothers (F 0 ) and daughters (F 1 ) that were raising litters of 10 pups. Cross-fostering was designed so that half of each litter consisted of biological offspring and the rest came from one unrelated female (i.e. fostered pups). Food intake increased linearly during early lactation and reached a plateau during late lactation (day 9-13, called the asymptotic food intake, FI AS , equivalent to SusEI). Parent-offspring regression showed that FI AS , MEO and litter mass were all positively and significantly related between mothers and their biological daughters, but no significant relationships were found between the same traits for mothers and fostered daughters. FI AS at peak lactation was significantly correlated to adult food intake and body mass when the mice were 6months old and not lactating. In conclusion, a large part of the variation in FI AS could be explained by genetic variation or maternal effects in pregnancy whereas non-genetic maternal effects in lactation were negligible. As a consequence, biological daughters of mothers with high reproductive performance (i.e. high milk production and hence higher litter mass at weaning) had a better reproductive performance themselves, independent of the mother that raised them during lactation.

Section: Discussionmentioning

confidence: 98%

Limits to sustained energy intake. XIV. Heritability of reproductive performance in mice

Vaanholt

Sinclair

Speakman

2013

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“…However, in laboratory mice the contribution of fat to the overall energy budget is relatively trivial (Johnson et al, 2001b;Speakman, 2008) (but see Duah et al, 2013). One suggestion is that the reduction in the size of fat tissue may reduce the production of leptin and other adipokines, which then serves to stimulate food intake (Halaas et al, 1997;Abelenda et al, 2003;Speakman, 2008;Cui et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

Limits to sustained energy intake. XVIII. Energy intake and reproductive output during lactation in Swiss mice raising small litters

Zhao

Song

et al. 2013

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SUMMARYLimits to sustained energy intake (SusEI) during lactation in Swiss mice have been suggested to reflect the secretory capacity of the mammary glands. However, an alternative explanation is that milk production and food intake are regulated to match the limited growth capacity of the offspring. In the present study, female Swiss mice were experimentally manipulated in two wayslitter sizes were adjusted to be between 1 and 9 pups and mice were exposed to either warm (21°C) or cold (5°C) conditions from day 10 of lactation. Energy intake, number of pups and litter mass, milk energy output (MEO), thermogenesis, mass of the mammary glands and brown adipose tissue cytochrome c oxidase activity of the mothers were measured. At 21 and 5°C, pup mass at weaning was almost independent of litter size. Positive correlations were observed between the number of pups, litter mass, asymptotic food intake and MEO. These data were consistent with the suggestion that in small litters, pup requirements may be the major factor limiting milk production. Pups raised at 5°C had significantly lower body masses than those raised at 21°C. This was despite the fact that milk production and energy intake at the same litter sizes were both substantially higher in females raising pups at 5°C. This suggests that pup growth capacity is lower in the cold, perhaps due to pups allocating ingested energy to fuel thermogenesis. Differences in observed levels of milk production under different conditions may then reflect a complex interplay between factors limiting maternal performance (peripheral limitation and heat dissipation: generally better when it is cooler) and factors influencing maximum pup growth (litter size and temperature: generally better when it is hotter), and may together result in an optimal temperature favouring reproduction.

“…Alternatively, or additionally, the elevation in T b might be associated indirectly with the hormonal secretions that induce and maintain milk production such as prolactin (Svennersten-Sjaunja and Olsson, 2005) and other hormonal changes that are linked to lactation such as the reduced levels of circulating leptin (Cui et al, 2011;Król et al, 2011). In fact, prolactin appears to be strongly positively correlated with T b during exertional heat stress (Pitsiladis et al, 2002;Wright et al, 2012), although in this case it appears the causal relationship is that elevated temperature stimulates prolactin release (Low et al, 2005) and not the reverse.…”

Section: Physical Activity and Body Temperature In Lactating Micementioning

confidence: 98%

Limits to sustained energy intake XX: body temperatures and physical activity of female mice during lactation

Gamo

Troup

Mitchell

et al. 2013

SUMMARYLactating animals consume greater amounts of food than non-reproductive animals, but energy intake appears to be limited in late lactation. The heat dissipation limit theory suggests that the food intake of lactating mice is limited by the capacity of the mother to dissipate heat. Lactating mice should therefore have high body temperatures (T b ), and changes in energy intake during lactation should be reflected by variation in T b . To investigate these predictions, 26 mice (Mus musculus) were monitored daily throughout lactation for food intake, body mass, litter size and litter mass. After weaning, 21days postpartum, maternal food intake and body mass were monitored for another 10days. Maternal activity and T b were recorded every minute for 23h a day using implanted transmitters (vital view). Energy intake increased to a plateau in late lactation (days 13-17). Daily gain in pup mass declined during this same period, suggesting a limit on maternal energy intake. Litter size and litter mass were positively related to maternal energy intake and body mass. Activity levels were constantly low, and mice with the largest increase in energy intake at peak lactation had the lowest activity. T b rose sharply after parturition and the circadian rhythm became compressed within a small range. T b during the light period increased considerably (1.1°C higher than in baseline), and lactating mice faced chronic hyperthermia, despite their activity levels in lactation being approximately halved. Average T b increased in relation to energy intake as lactation progressed, but there was no relationship between litter size or litter mass and the mean T b at peak lactation. These data are consistent with the heat dissipation limit theory, which suggests performance in late lactation is constrained by the ability to dissipate body heat. Supplementary material available online at