Limits to sustained energy intake. XIX. A test of the heat dissipation limitation hypothesis in Mongolian gerbils (Meriones unguiculatus)
Limits to sustained energy intake. XIX. A test of the heat dissipation limitation hypothesis in Mongolian gerbils (Meriones unguiculatus)
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DOI：
10.1242/jeb.085233
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发表时间：
2013-09
影响因子：
2.8
通讯作者：
Dengbao Yang;Li Li-Li;Lulu Wang;Qing-sheng Chi;C. Hambly;Dehua Wang;J. Speakman
中科院分区：
文献类型：
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作者：
Dengbao Yang;Li Li-Li;Lulu Wang;Qing-sheng Chi;C. Hambly;Dehua Wang;J. Speakman
我们评估了三种温度（10、21和30°C）下限制哺乳蒙古沙鼠（长爪沙鼠）的因素。能量摄入和每日能量消耗（DEE）随着环境温度的降低而增加。在泌乳高峰期（泌乳期第14天），能量摄入量从30°C时的148.7±5.7 kJ/d − 1增加到21°C时的213.1±8.2 kJ/d − 1和10°C时的248.7±12.3 kJ/d − 1。在泌乳期第14-16天，DEE从30°C时的105.1±4.0 kJ/天增加到21°C时的134.7±5.6 kJ/天和10°C时的179.5±8.4 kJ/天。在平均窝仔数几乎相同的情况下，在30°C下泌乳的沙鼠在泌乳高峰期以乳汁形式输出的能量比分配到10或21°C的沙鼠少32.0 kJ/天，后两组之间没有差异。在哺乳期第14天，10和30°C下的窝重分别比21°C下的窝重低12.2和9.3 g。哺乳期沙鼠有较高的导热系数的皮毛和较低的UCP-1水平的棕色脂肪组织比非生殖沙鼠，独立于环境温度，这表明他们试图避免热应激。皮毛的热导率与循环催乳素水平呈正相关。我们植入非生殖沙鼠与微型渗透泵，提供催乳素或生理盐水。催乳素不影响皮毛的导热性，但确实减少了体力活动和棕色脂肪组织中的UCP-1水平。将哺乳期沙鼠从温暖条件转移到热条件导致产奶量减少，与散热极限理论一致，但将它们从温暖条件转移到冷条件并没有提高产奶量，与外周限制假说一致，并对幼鼠生长产生限制。
We evaluated factors limiting lactating Mongolian gerbils (Meriones unguiculatus) at three temperatures (10, 21 and 30°C). Energy intake and daily energy expenditure (DEE) increased with decreased ambient temperature. At peak lactation (day 14 of lactation), energy intake increased from 148.7±5.7 kJ day−1at 30°C to 213.1±8.2 kJ day−1at 21°C and 248.7±12.3 kJ day−1at 10°C. DEE increased from 105.1±4.0 kJ day−1at 30°C to 134.7±5.6 kJ day−1at 21°C and 179.5±8.4 kJ day−1at 10°C on days 14–16 of lactation. With nearly identical mean litter sizes, lactating gerbils at 30°C exported 32.0 kJ day−1less energy as milk at peak lactation than those allocated to 10 or 21°C, with no difference between the latter groups. On day 14 of lactation, the litter masses at 10 and 30°C were 12.2 and 9.3 g lower than those at 21°C, respectively. Lactating gerbils had higher thermal conductance of the fur and lower UCP-1 levels in brown adipose tissue than non-reproductive gerbils, independent of ambient temperature, suggesting that they were attempting to avoid heat stress. Thermal conductance of the fur was positively related to circulating prolactin levels. We implanted non-reproductive gerbils with mini-osmotic pumps that delivered either prolactin or saline. Prolactin did not influence thermal conductance of the fur, but did reduce physical activity and UCP-1 levels in brown adipose tissue. Transferring lactating gerbils from warm to hot conditions resulted in reduced milk production, consistent with the heat dissipation limit theory, but transferring them from warm to cold conditions did not elevate milk production, consistent with the peripheral limitation hypothesis, and placed constraints on pup growth.