Assessment of the Response of murine NR-S1 tumor following irradiation monitored by P-31 NMR Spectroscopy

本课题的目的是通过P-31核磁共振波谱监测评价X射线或中子照射对小鼠NR-S1肿瘤的反应，并从能量代谢、细胞内pH等方面阐明该肿瘤的放射敏感性。为了达到这一目标，设置了3个受试者，并进行了平行试验。1.肿瘤生长过程中，肿瘤的正常生长，出现代谢剥夺区域，其特征可能是低氧和由此导致的高能磷酸盐(包括ATP、磷酸肌酸(PCr)和pH)的减少。2.单次X或中子照射后，NR-S1肿瘤的反应在3-4小时内出现PI/PCR值的初步增加。PI/PCR值在照射后2~3d明显降低。这种现象可能是肿瘤细胞在复氧状态下代谢的改变。不同剂量(10GY、2OGY)的中子照射后，肿瘤细胞的能量代谢也有不同程度的变化。III.在均匀分割X射线照射下，NR-S1肿瘤的能量代谢变化不明显。照射后2~3d，照射后2~3d能量状态恢复率各组间基本相同。总而言之，P-31MRS在肿瘤能量代谢的非侵入性研究中是相当重要的，它影响了包括放射治疗在内的大多数治疗手段的结果。

The purpose of the present project is to assess the response of X-or Neutron irradiation to Murine NR-S1 tumor monitored by P-31 NMR Spectroscopy and to elucidate the radiosensitivity of this tumor from the point of energy metabolism, intracellular pH. Toward this goal, 3 subjects were set and have been carried out in parallel.I. Normal growth of NR-S1 tumor During tumor growth, areas of metabolic deprivation develop which may be characterized by hypoxia and resultant reduction in high energy phosphates, including ATP, phosphocreatine (PCr) and pH.II. Response of NR-S1 tumor following a single dose of X or Neutron irradiation After single dose of X-irradiation (25Gy, 5OGy), initial increase of Pi/PCr within 3-4 hours was occurred. The significant reduction of Pi/PCr was noted 2- 3 days after following irradiation. This phenomena may be a change in tumor cell metabolism with reoxygenation. In contrast, the same changes were noted after Neutron-irradiation in the doses (10GY, 2OGy) less than the dose of X- irradiation.III. Response of NR-S1 tumor following fractionated X-irradiation In the even fractionated X-irradiation, the changes of energy metabolism were not significant more than the changes of the single dose irradiation. With 2 fractions of 25 Gy at interval of 4 hours or 24 hours, the recover rates of energy status 2-3 days after irradiation were mostly the same within these groups. In contrast, in the group of the split interval of 24 hours, the recovery was noted mostly significant.In conclusion, P-31 MRS has been considerable for non-invasive investigation of tumor energy metabolism and which influence the outcome of most therapeutic modalities, including radiotherapy.