OXALIPLATIN PLUS DIFFERENT FRACTIONATED RADIOTHERAPY: ITS IMPACT ON RECENT BIOLOGICAL EFFECTS OF ADRENAL GLAND IN RATS
Objective To study the influence of oxaliplatin combined with different fractionated radiotherapy (DFR) on recent biological effects of adrenal gland in rats.Methods A total of 150 Wistar rats were randomized to five groups as:group A (control group),group B (simple oxaliplatin chemotherapy),group C (oxaliplatin +convention fraction radiotherapy,12 Gy,5 times a week),group D (oxaliplatin+hypo-fraction irradiation,12 Gy,2 times a week) and group E (oxaliplatin+high-dose fraction,12 Gy,once a week).The rats in groups C,D and E were given intra-peritoneal injection of oxaliplatin (15 mg/kg) first and followed by 6 MV X-ray irradiation,the total radiation dose was 12 Gy.Before and on days 3,7 14 and 30 after irradiation,six rats in each group were sacrificed at 8 o'clock under deep anesthesia.Serum cortical levels were determined,and adrenal histological changes observed.Results Third day after irradiation,cortisol secretion in rats of groups B,C,D and E increased,and dilated congestion in capillary network in the adrenal medulla could be seen;on day 7,the secretion of cortisol declined,compared with the previous,and the volume of adrenal cortex showed different degrees of reduction;on day 14,the blood cortisol decreased to basal level,and compensatory hyperplasia of adrenal cortical band ceils developed;on day 30,blood cortisol secretion mildly elevated,and adrenal morphology recovered.On third day after irradiation,there was a significant dose-effect relationship between blood cortisol levels and irradiation dose (F=25.340,P<0.01).Conclusion Concurrent chemo-radiotherapy may cause acute adrenal injury in rats,after different fractionated irradiation,periodic and adaptive changes occur in secretion volume of cortisol and adrenal morphology,which is associated with the dose of irradiation.