An increase in [3H]QNB binding by proton-beam irradiation in intact rat brain: an apparent positive cooperativity of binding.
After focal irradiation of rat brains with a beam of proton (dose, 30 Gy), [3H]quinuclidinyl benzilate (QNB) binding, both in vitro and in vivo, was measured, using either autoradiographic or tissue-dissection methods. No changes in in vitro [3H]QNB binding were seen in autoradiograms of brain slices from irradiated rat. The irradiated side of the brain showed a significant increase in [3H]QNB binding in vivo in the striatum and cerebral cortex 24 h after irradiation. This increase in binding was transient, and had almost disappeared 2 weeks after irradiation. These results indicate that early changes in receptor function as a results of radiation damage are only detected in in-vivo conditions. In the striatum of the intact rat brain, an apparent positive cooperativity of binding was observed, which was more pronounced on the irradiated side.
School of Allied Health Sciences, Osaka University Faculty of Medicine, Japan. inoue@shahs.med.osa-u.ac.jp
O
O
Inoue
K
K
Kobayashi
N
N
Takai
Y
Y
Furusawa
K
K
Ando
T
T
Nakano
T
T
Nishimura
D000818:Animals; D001921:Brain / Q000528:radiation effects*; D005720:Gamma Rays; D008297:Male; D011485:Protein Binding / Q000528:radiation effects; D011522:Protons; D011813:Quinuclidinyl Benzilate / Q000378:metabolism* / Q000528:radiation effects; D011849:Radioactive Tracers; D051381:Rats; D017208:Rats, Wistar; D014316:Tritium
D011522:Protons; D011849:Radioactive Tracers; D014316:Tritium; D011813:Quinuclidinyl Benzilate