Indomethacin attenuation of radiation-induced hyperthermia does not modify radiation-induced motor hypoactivity.
Exposure of rats to 5-10 Gy of ionizing radiation produces hyperthermia and reduces motor activity. Previous studies suggested that radiation-induced hyperthermia results from a relatively direct action on the brain and is mediated by prostaglandins. To test the hypothesis that hypoactivity may be, in part, a thermoregulatory response to this elevation in body temperature, adult male rats were given indomethacin (0.0, 0.5, 1.0, and 3.0 mg/kg, intraperitoneally), a blocker of prostaglandin synthesis, and were either irradiated (LINAC 18.6 MeV (nominal) high-energy electrons, 10 Gy at 10 Gy/min, 2.8 microseconds pulses at 2 Hz) or sham-irradiated. The locomotor activity of all rats was then measured for 30 min in a photocell monitor for distance traveled and number of vertical movements. Rectal temperatures of irradiated rats administered vehicle only were elevated by 0.9 +/- 0.2 degree C at the beginning and the end of the activity session. Although indomethacin, at the two higher doses tested, attenuated the hyperthermia in irradiated rats by 52-75%, it did not attenuate radiation-induced reductions in motor activity. These results indicate that motor hypoactivity after exposure to 10 Gy of high-energy electrons is not due to elevated body temperature or to the increased synthesis of prostaglandins.
Ferguson
J L
JL
Armed Forces Radiobiology Research Institute, Bethesda, MD 20889-5603, USA.
Kandasamy
S B
SB
Harris
A H
AH
Davis
H D
HD
Landauer
M R
MR
D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects / Q000528:radiation effects; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D005334:Fever / Q000209:etiology* / Q000517:prevention & control*; D007213:Indomethacin / Q000494:pharmacology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects* / Q000528:radiation effects*; D011453:Prostaglandins / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley
D016861:Cyclooxygenase Inhibitors; D011453:Prostaglandins; D007213:Indomethacin