Park C S, Baik M G, Keller W L, Slanger W D
Department of Animal and Range Sciences, North Dakota State University, Fargo 58105.
J Anim Sci. 1994 Sep;72(9):2319-24. doi: 10.2527/1994.7292319x.
This research examined the extent to which dietary energy restriction modulates growth and mammary tissue composition during different developmental stages. Female rats were assigned to the following three dietary treatments: 1) ad libitum access to feed (AL), 2) 30% continuous energy restriction (CER), and 3) stair-step energy restriction (SSER). The SSER treatment consisted of an 8-wk, alternating schedule beginning with 60% energy restriction for 2 wk, followed by realimentation to feed offered for ad libitum intake for 2 wk. All treatments were initiated when rats were 5 wk of age. After the stair-step regimen, SSER rats were maintained on a 30% energy-restricted diet for the duration of the experimental period (25 wk of age). Rats reared on the energy restriction regimens weighed less and consumed less (P < .05) feed than controls, but they had feed efficiencies similar to those of controls. Energy restriction delayed the onset of puberty and retarded the growth of the offspring but had no effect on litter size. The overall values (averaged pregnancy through involution stages) of DNA, RNA, and RNA: DNA ratio (based on fat-free DM) and protein concentrations were similar in the mammary tissues of the energy restriction groups and those of the AL group. Lipid content in mammary tissue was generally decreased in the CER and SSER groups compared with the AL group. In summary, energy restriction delayed the onset of puberty and retarded the growth of the dam and progeny, but it did not affect mammary cellularity as it reduced fat deposition in the mammary gland.
本研究考察了不同发育阶段饮食能量限制对生长和乳腺组织组成的调节程度。将雌性大鼠分为以下三种饮食处理组：1）自由采食（AL），2）30%持续能量限制（CER），3）阶梯式能量限制（SSER）。SSER处理包括一个为期8周的交替方案，开始时进行60%能量限制，持续2周，随后恢复自由采食2周。所有处理在大鼠5周龄时开始。经过阶梯式方案后，SSER组大鼠在实验期（25周龄）内维持30%能量限制饮食。与对照组相比，接受能量限制方案饲养的大鼠体重较轻，采食量较少（P < 0.05），但它们的饲料效率与对照组相似。能量限制延迟了青春期的开始并阻碍了后代的生长，但对产仔数没有影响。能量限制组和AL组乳腺组织中DNA、RNA、RNA:DNA比值（基于无脂干物质）和蛋白质浓度的总体值（从妊娠到 involution 阶段的平均值）相似。与AL组相比，CER组和SSER组乳腺组织中的脂质含量普遍降低。总之，能量限制延迟了青春期的开始并阻碍了母鼠和后代的生长，但它并不影响乳腺细胞数量，因为它减少了乳腺中的脂肪沉积。
