Mosier H D, Good C B, Jansons R A, Sondhaus C A, Dearden L C, Alpizar-S M, Zuniga O F
Growth. 1983 Spring;47(1):13-25.
The heads of 2 day old male and female rats were X-irradiated with 600 rad. Non-irradiated littermates served as controls. At 40 days of age groups of irradiated and non-irradiated rats were subjected to a 48 hour fast. Non-fasted groups of irradiated and non-irradiated rats were fed ad lib. and were used for comparative studies. Growth of body weight and tail length was recorded at intervals through 70 days of age. At sacrifice, pituitary weight, tibial length, and tibial epiphyseal width were also determined. The results confirm earlier findings that whole head irradiation produces reduced growth of body weight and of tail length which remains uncompensated by catch-up growth. After fasting and then refeeding normal catch-up growth acceleration occurred in both male and female irradiated and nonirradiated animals. The fasted non-irradiated animals caught up to the non-irradiated control rat size for both body weight and tail length. Similarly, the fasted irradiated rats caught up to the irradiated, non-fasted rat size, but did not catch up to the size of the non-irradiated controls. Pituitary weight and tibial length were significantly reduced in irradiated males and females. At sacrifice, no significant difference existed between the fasted and non-fasted subgroups. The tibial epiphyseal growth plate was not narrowed in irradiated rats; fasted rats had increased epiphyseal width during recovery in only one group. We conclude that the catch-up growth control is intact in the head-irradiated stunted rat. The findings suggest that the mechanism which recognizes normal body size (set-point for body size) and which determines the limit of catch-up growth acceleration is reset for a smaller body size by the head-irradiation.
对2日龄雄性和雌性大鼠的头部进行600拉德的X射线照射。未照射的同窝仔鼠作为对照。在40日龄时，将照射组和未照射组的大鼠禁食48小时。照射组和未照射组的非禁食大鼠随意进食，用于比较研究。在70日龄前定期记录体重和尾长的增长情况。处死时，还测定垂体重量、胫骨长度和胫骨骨骺宽度。结果证实了早期的研究结果，即全头部照射会导致体重和尾长生长减缓，且不会因追赶生长而得到补偿。禁食后再喂食，雄性和雌性照射组和未照射组的动物均出现正常的追赶生长加速。禁食的未照射动物在体重和尾长方面均赶上了未照射的对照大鼠的大小。同样，禁食的照射大鼠赶上了未禁食的照射大鼠的大小，但没有赶上未照射对照大鼠的大小。照射的雄性和雌性大鼠的垂体重量和胫骨长度显著降低。处死时，禁食和非禁食亚组之间没有显著差异。照射大鼠的胫骨骨骺生长板没有变窄；只有一组禁食大鼠在恢复期间骨骺宽度增加。我们得出结论，头部照射导致发育迟缓的大鼠的追赶生长控制是完整的。研究结果表明，识别正常体型（体型设定点）并确定追赶生长加速极限的机制因头部照射而针对较小体型进行了重置。
