Wilde C J, Knight C H, Racey P A
Hannah Research Institute, Ayr, United Kingdom.
J Exp Zool. 1999 Jun 15;284(1):35-41. doi: 10.1002/(sici)1097-010x(19990615)284:1<35::aid-jez6>3.0.co;2-z.
In the pipistrelle bat (Pipistrellus pipistrellus), the metabolic load of lactation is not met to any significant extent by increased food intake or mobilization of body reserves, and aerial foraging accounts for most of the animal's energy expenditure even during lactation. Energy conservation must, therefore, play a critical role in maintaining lactation. The principal mechanism for energy conservation appears to be the bat's ability to enter torpor, but this may itself interrupt milk synthesis and secretion unless the pipistrelle mammary gland is adapted to counteract its effect. The effect of torpor on mammary tissue function was studied in mammary tissue explant cultures prepared in weeks 1-3 of lactation, when milk water yield was 0.20, 0.88, and 0.30 mL/d respectively. Protein synthesis measured by incorporation of radiolabeled amino acids was 44% lower (P < 0.001) in bat tissue explants cultured at ambient temperature (22 degrees C) compared with 37 degrees C. The reduction was similar to that observed in mouse mammary tissue (57%) and was unaffected by stage of lactation. Analysis of explant protein after [35S]methionine labelling showed the majority of proteins synthesised in culture to be milk proteins; it also demonstrated that the decrease in protein synthesis at ambient temperature was a general phenomenon: synthesis of both secretory and intracellular mammary proteins was reduced at the lower culture temperature. The results suggest that bat mammary tissue has no mechanism to counteract the effect of reduced body temperature and that periods of lactational torpor are likely to cause a pronounced diurnal variation in the rate of milk secretion.
在伏翼蝠（ Pipistrellus pipistrellus ）中，泌乳的代谢负荷无法通过增加食物摄入量或动用身体储备来显著满足，即使在泌乳期间，空中觅食也占该动物能量消耗的大部分。因此，节能在维持泌乳过程中必定起着关键作用。节能的主要机制似乎是蝙蝠进入蛰伏状态的能力，但这本身可能会中断乳汁的合成和分泌，除非伏翼蝠的乳腺能够适应以抵消其影响。在泌乳第1 - 3周制备的乳腺组织外植体培养物中研究了蛰伏对乳腺组织功能的影响，此时乳汁产量分别为0.20、0.88和0.30 mL/天。与37℃培养相比，在环境温度（22℃）下培养的蝙蝠组织外植体中，通过放射性标记氨基酸掺入法测量的蛋白质合成降低了44%（P < 0.001）。这种降低与在小鼠乳腺组织中观察到的情况（57%）相似，并且不受泌乳阶段的影响。对[35S]甲硫氨酸标记后的外植体蛋白质分析表明，培养物中合成的大多数蛋白质是乳蛋白；这也表明在环境温度下蛋白质合成的降低是一个普遍现象：在较低的培养温度下，分泌性和细胞内乳腺蛋白的合成均减少。结果表明，蝙蝠乳腺组织没有机制来抵消体温降低的影响，并且泌乳期的蛰伏可能会导致乳汁分泌速率出现明显的昼夜变化。
