Gursoy E, Cardounel A, Hu Y, Kalimi M
Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0551, USA.
Exp Biol Med (Maywood). 2001 Feb;226(2):97-102. doi: 10.1177/153537020122600206.
In the present study, we have established the biological effects during 8 weeks of (i) caloric restriction (Cal) and (ii) simultaneous administration of Cal plus 2 hr daily immobilization stress using male Sprague-Dawley rats. Animals were divided into three equal groups: (i) ad libitum fed, (ii) 30% restriction of food intake of the ad libitum diet, and (iii) 30% restriction of food intake plus 2 hr daily immobilization stress. Caloric-restricted animals gained only 30% of the total body weight of the unrestricted animals but received 70% of the food of those rats. Cal animals showed a significant loss in their relative liver and-thymus weight and a significant gain in their relative adrenal and testis weight as compared to the control animals. Cal animals had almost 2-fold higher levels of plasma corticosterone levels with a dramatic decrease in the total glucocorticoid receptor (GR) levels in the liver, thymus, heart, and testis as compared to ad libitum fed control animals. Interestingly, Cal animals showed higher levels of lipid peroxidation in both the liver and heart, indicating increased oxidative activities in these tissues when compared with the control animals. In addition, Cal animals had increased heat shock protein 70 (HSP 70) content in the testis. Surprisingly, hardly any significant differences were observed in either total body weight gain, organ weights, plasma corticosterone levels, or lipid peroxidation between Cal animals and Cal plus immobilization-stressed animals. The results obtained suggest that (i) several stress-related responses such as inhibition of total body weight gain, increased adrenal weight, decreased thymus weight, increased plasma corticosterone, and lipid peroxidation levels in the liver and heart are associated with Cal, but (ii) no additional effects were observed on the parameters that were measured when two stress regimens were given simultaneously, suggesting that animals subjected to two stress regimens can protect themselves by controlling their stress-related thresholds of response through adaptation.
在本研究中，我们利用雄性斯普拉格 - 道利大鼠确定了（i）热量限制（Cal）以及（ii）同时进行Cal并每日固定应激2小时，持续8周期间的生物学效应。动物被分为三组，每组数量相等：（i）自由采食组，（ii）自由采食组食物摄入量限制30%，（iii）食物摄入量限制30%并每日固定应激2小时。热量限制的动物体重增加量仅为非限制动物总体重的30%，但食物摄入量为那些大鼠的70%。与对照动物相比，Cal组动物肝脏和胸腺的相对重量显著降低，肾上腺和睾丸的相对重量显著增加。与自由采食的对照动物相比，Cal组动物血浆皮质酮水平几乎高出2倍，肝脏、胸腺、心脏和睾丸中的总糖皮质激素受体（GR）水平显著降低。有趣的是，Cal组动物肝脏和心脏中的脂质过氧化水平较高，表明与对照动物相比，这些组织中的氧化活性增加此外，Cal组动物睾丸中的热休克蛋白70（HSP 70）含量增加。令人惊讶的是，在Cal组动物和Cal加固定应激组动物之间，在总体重增加、器官重量、血浆皮质酮水平或脂质过氧化方面几乎未观察到任何显著差异。所得结果表明：（i）一些与应激相关的反应，如总体重增加受抑制、肾上腺重量增加、胸腺重量降低、血浆皮质酮增加以及肝脏和心脏中的脂质过氧化水平升高，与Cal有关，但（ii）同时给予两种应激方案时，在所测量的参数上未观察到额外影响，这表明遭受两种应激方案的动物可以通过适应来控制其与应激相关的反应阈值，从而实现自我保护。
