Effect of whole body hyperthermia (39°C, 1 h) on radiation-induced apoptosis in Swiss mice

Abstract

Mild whole body hyperthermia (WBH) treatment when given prior to radiation exposure is known to protect mice against radiation-induced hemopoietic death. This radioprotective effect seems to be mediated through WBH-induced cytokines and growth factors. Exposure to total body irradiation (TBI) also induces cell death by apoptosis in animal cells. The present studies were therefore carried out to investigate whether WBH pretreatment could protect mice against radiation-induced apoptotic death. The extent of apoptosis in bone marrow cells derived from mice at different time intervals after WBH, TBI and whole body hyperthermia treatment given 20 h prior to total body irradiation (WBH+TBI) treatments was studied by three independent methods namely DNA ladder assay, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling assay and caspase-3 assay. The studies have revealed that the mild WBH treatment (39°C, 1 h) when given 20 h prior to TBI (8 Gy) results in reduction in TBI-induced apoptosis. The results imply that WBH-induced impairment of apoptosis may have some role in WBH-induced radioprotection in Swiss mice.