Gross L, Dreyfuss Y
Cancer Research Unit, Veterans Affairs Medical Center, Bronx, NY 10468.
Proc Natl Acad Sci U S A. 1990 Sep;87(17):6795-7. doi: 10.1073/pnas.87.17.6795.
In our previous studies carried out on inbred Sprague-Dawley rats, we reported a striking increase in the incidence of tumors following total-body gamma-irradiation [150 rads (1.5 Gy) five times at weekly intervals]. Subsequently, we observed that two or three irradiations, and to a lesser extent even a single irradiation, were sufficient to induce an impressive increase in the incidence of tumors, particularly in females. A significant reduction of the incidence of radiation-induced tumors resulted when the rats were placed on calorically restricted diet. In experiments reported here, we increased slightly the amount of food given to animals on restricted diet. In the new study, among 102 irradiated females on full diet, 91 (89%) developed tumors, as compared with 29 out of 128 female rats (23%) also irradiated but maintained on restricted diet and 43 out of 89 (48%) untreated control females. None of 77 nonirradiated females on restricted diet developed tumors. Among 65 irradiated male rats, 29 (45%) developed tumors, as compared with 5 out of 74 (7%) rats also irradiated but maintained on restricted diet. Of the 49 males in the nonirradiated groups, 2 (4%) developed tumors. There was a significant weight reduction in both females and males maintained on restricted diet; animals on restricted diet lived longer than those on full diet.
在我们之前对近交系斯普拉格-道利大鼠进行的研究中，我们报告了全身γ射线照射后（每周1次，每次150拉德（1.5戈瑞），共5次）肿瘤发生率显著增加。随后，我们观察到两三次照射，甚至在较小程度上单次照射，就足以使肿瘤发生率显著增加，尤其是在雌性大鼠中。当给大鼠喂食热量限制饮食时，辐射诱导肿瘤的发生率显著降低。在本文报告的实验中，我们略微增加了给予限制饮食动物的食物量。在新的研究中，102只接受全量饮食的辐照雌性大鼠中有91只（89%）发生了肿瘤，相比之下，128只同样接受辐照但维持限制饮食的雌性大鼠中有29只（23%）发生了肿瘤，89只未接受处理的对照雌性大鼠中有43只（48%）发生了肿瘤。77只接受限制饮食的未辐照雌性大鼠均未发生肿瘤。65只辐照雄性大鼠中有29只（45%）发生了肿瘤，相比之下，74只同样接受辐照但维持限制饮食的大鼠中有5只（7%）发生了肿瘤。在未辐照组的49只雄性大鼠中，有2只（4%）发生了肿瘤。维持限制饮食的雌性和雄性大鼠体重均显著减轻；限制饮食的动物比全量饮食的动物寿命更长。
