Newberne P M, Young V R, Gravlee J F
Br J Exp Pathol. 1969 Apr;50(2):172-80.
In 3 separate trials a total of 48 purebred beagles were divided into 2 groups and fed a balanced diet supplying either 90-100 kcal./kg. body wt or 40-50 kcal./kg. body wt per day. The higher caloric intake resulted in an increase of 50-80 per cent of initial body wt after 5 or 6 weeks on the diet. The low-intake group lost about 10 per cent of initial body wt during the 6-week period. At the end of this period 12 dogs from each dietary group were exposed to distemper virus by intracerebral inoculation. In high-fed dogs the concentration of liver protein decreased significantly after inoculation. Of the free essential amino acids of the liver, threonine, valine and methionine decreased by day 3 post-inoculation as well as the ratio of the total essential to total non-essential (E/N) amino acids. Liver RNA was increased on day 3 and significantly lower on days 5 and 7. Cerebral RNA and DNA were lower on day 3, but showed no difference at day 5. In contrast to the results with high-fed dogs, the liver protein content of low-fed dogs increased as a result of infection. Infection also increased the levels of some of the essential amino acids by day 3 in this dietary group. Furthermore, the E/N ratio increased in the livers of this group after 3 days of infection. In general, changes in serum concentrations of the amino acids were not reflected by changes in liver concentrations. For infected dogs in this dietary group, liver RNA was lower on day 5 and higher on day 7 than in control animals. Cerebral DNA was lower on day 3 and higher on day 5 in infected dogs, whereas RNA was lower on both days. Cerebral protein content showed no change in either dietary group after infection. The physiological relationship between these chemical changes and the resistance of the host to infection is not completely understood. However, the present results suggest that the decreased resistance of high-fed dogs to infection is related in a complex way to changes in protein metabolism and hormone balance.
在3项独立试验中，总共48只纯种比格犬被分成2组，分别喂食提供90 - 100千卡/千克体重或40 - 50千卡/千克体重的均衡日粮，每日如此。较高的热量摄入导致在按该日粮喂养5或6周后，体重比初始体重增加了50% - 80%。低摄入组在6周期间体重减轻了约10%。在此期间结束时，每个饮食组的12只狗通过脑内接种感染犬瘟热病毒。在高喂食量的狗中，接种后肝脏蛋白质浓度显著下降。肝脏中的游离必需氨基酸，苏氨酸、缬氨酸和蛋氨酸在接种后第3天下降，同时必需氨基酸总量与非必需氨基酸总量的比值（E/N）也下降。肝脏RNA在第3天增加，在第5天和第7天显著降低。脑RNA和DNA在第3天较低，但在第5天没有差异。与高喂食量狗的结果相反，低喂食量狗的肝脏蛋白质含量因感染而增加。感染在该饮食组中也使一些必需氨基酸水平在第3天增加。此外，该组肝脏在感染3天后E/N比值增加。一般来说，血清氨基酸浓度的变化并未反映在肝脏浓度的变化中。对于该饮食组中受感染的狗，肝脏RNA在第5天低于对照组动物，在第7天高于对照组动物。受感染狗的脑DNA在第3天较低，在第5天较高，而RNA在这两天都较低。感染后，两个饮食组的脑蛋白质含量均未显示变化。这些化学变化与宿主抗感染能力之间的生理关系尚未完全明了。然而，目前的结果表明，高喂食量狗抗感染能力的下降与蛋白质代谢和激素平衡的变化以复杂的方式相关。
