van den Hemel-Grooten H N, te Pas M F, van den Bosch T J, Garssen G J, Schreurs V V, Verstegen M W
DLO-Institute for Animal Science and Health (ID-DLO), Department of Food Science, Lelystad, The Netherlands.
J Anim Sci. 1997 Apr;75(4):968-74. doi: 10.2527/1997.754968x.
This experiment was conducted to investigate the effects of feeding a protein-free diet on mRNA levels of the calpain system in skeletal muscle of growing pigs during a 15-d feeding trial. Twenty crossbred barrows were divided into two dietary treatments: control or protein-free diet (mean initial weight for both groups: 38.3 kg). Daily diets were provided at 2.5 times energy for maintenance (twice a day). On d 0, 3, and 14, biopsies were taken from longissimus muscle between the third and fourth ribs (d 0 and 3) and between the fourth and fifth rib (d 14). On d 15, animals were slaughtered and longissimus muscles were dissected and analyzed for calpastatin, and mu- and m-calpain activity. From biopsies, mRNA level of skeletal muscle calpain, mu- and m-calpain, and calpastatin were measured using reversed transcription PCR. Subsequently, PCR products were quantified using ELISA. Feeding the protein-free diet lowered growth rate to almost zero. Only total level of mRNA of mu-calpain on d 14 was influenced by dietary treatments, being lower for the protein-free group than for the control group (P < .05). However, proteolytic activities were not different between treatments. Total RNA concentration in longissimus muscle decreased during the experiment for both treatments, but on d 14 this was more pronounced for the protein-free than for the control group (P < .05). If mRNA levels were corrected for this change, specific mRNA level on d 14 of skeletal muscle calpain and mu-calpain were lower (P < .05) for the protein-free than for the control group. These data suggest that activity of the components of the calpain system are differentially regulated.
本试验旨在通过15天的饲养试验，研究饲喂无蛋白日粮对生长猪骨骼肌中钙蛋白酶系统mRNA水平的影响。将20头杂交公猪分为两种日粮处理组：对照组和无蛋白日粮组（两组的平均初始体重均为38.3千克）。每天提供维持能量2.5倍的日粮（每天两次）。在第0天、第3天和第14天，从第三和第四肋骨之间（第0天和第3天）以及第四和第五肋骨之间（第14天）的背最长肌采集活检样本。在第15天，屠宰动物，解剖背最长肌，分析钙蛋白酶抑制蛋白、μ-钙蛋白酶和m-钙蛋白酶的活性。从活检样本中，使用逆转录PCR测量骨骼肌钙蛋白酶、μ-钙蛋白酶和m-钙蛋白酶以及钙蛋白酶抑制蛋白的mRNA水平。随后，使用酶联免疫吸附测定法对PCR产物进行定量。饲喂无蛋白日粮使生长速度降至几乎为零。仅第14天μ-钙蛋白酶的mRNA总水平受日粮处理影响，无蛋白组低于对照组（P < 0.05）。然而，各处理之间的蛋白水解活性没有差异。在实验过程中，两种处理的背最长肌总RNA浓度均下降，但在第14天，无蛋白组比对照组下降更明显（P < 0.05）。如果对mRNA水平进行这种变化的校正，无蛋白组第14天骨骼肌钙蛋白酶和μ-钙蛋白酶的特定mRNA水平低于对照组（P < 0.05）。这些数据表明，钙蛋白酶系统各组分的活性受到不同的调节。
