Short term systemic effects of head and neck irradiation

Background Various localized side effects which accompany head and neck irr adiation [IR] have been widely reported. However, systemic side effects/hav e been only sparsely reported in the short-term period post-IR in an animal model The potential modulatory role of zinc-desferrioxamine [Zn-DFO] on IR effects was examined because of its known ability to protect against the d amage induced by free radicals which are mediated by redox-active metal ion s. Materials and Methods. We used three groups of male Wistar rats: a] sham irradiated controls b] irradiated [15 Gy]; c] irradiated and treated with Zn-DFO [20 mg/k] one hour prior. to IR. During the first two weeks post-IR, body weight and food and water intake were monitored daily, while lymphocy tes, segmented neutrophil and white blood cells [WBC] were counted at 20 mi nutes 4 and 16 hours and 1,3,7 and 14 days. Serum TNF-a and IL-6 were obtai ned at 10 minutes and 7 days. Results. On day 7 post-IR, body weight and fo od and water intake were reduced by 84% 96% and 85% [p<0.01] respectively i n the above mentioned three groups Of rats. This resulted in the death of 2 2% of the animals and was followed by recovery towards the end of the secon d week. At all time points examined between 10 minutes and 14 days, WBC wer e reduced by 52-74%. On the 7th day, Zn-DFO demonstrated a 33% protective e ffect against the WBC reduction. At 10 mins post-IR, a 84.8-fold [p<0.01] i na ease of TNF-a, but not IL-6, was noted. However; on the 7th day post-IR, both TNF-a and IL-6 levels were increased by 48.5-fold and 102.5-fold [0.0 1] respectively. Conclusion. The data presented delineate the severe short- term systemic effects of head and neck IR in a Int model We suggest conside ring the severe cachectic and immunocompromised status of the animals when performing various short-term studies with this model. During this period n utritional and immunological support for the examined animals is recommende d Further evaluation of the underlying mechanisms of IR-induced leukopenia and cachexia in animals and the possible implications far humans is warrant ed.