Radiation-induced apoptosis of oligodendrocytes in the adult rat optic chiasm.
OBJECTIVE
The present study characterized glial cell injury provoked in adult rat chiasm within 24 hours after a single, high-dose irradiation of 20 Gy.


METHODS
All chiasmal glial cells in a section were counted, and the percentage of TUNEL-positive glial cells exhibiting apoptotic morphology was defined as the apoptotic rate.


RESULTS
Numbers of apoptotic cells increased significantly (p<0.0001) from 3 to 8 hours after exposure, but returned to baseline levels by 24 hours. Little evidence of apoptosis was observed in non-irradiated chiasms. Similar patterns of increase in apoptotic rate were observed in the genu of the corpus callosum, but the extent was significantly lower (p=0.047) in the optic chiasm, with a maximal rate of 1.9%. Immunohistochemically, apoptotic cells were positive for CNP, a marker for oligodendrocytes.


CONCLUSIONS
These data indicate that chiasmal irradiation induces limited, but significant apoptotic depletion of the oligodendroglial population, and may participate in the development of radiation-induced optic neuropathy.
Nagayama
Kazuki
K
Department of Neurosurgery, Kyorin University School of Medicine, 6-20-2, Shinkawa, Mitaka-city, Tokyo 181-8611, Japan. knagayama-nsu@umin.ac.jp
Kurita
Hiroki
H
Nakamura
Masanao
M
Kusuda
Junko
J
Tonari
Ayako
A
Takayama
Makoto
M
Fujioka
Yasunori
Y
Shiokawa
Yoshiaki
Y
D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D002452:Cell Count; D003337:Corpus Callosum / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D007150:Immunohistochemistry / Q000379:methods; D020287:In Situ Nick-End Labeling; D008297:Male; D043583:Nucleoside-Triphosphatase / Q000378:metabolism; D009836:Oligodendroglia / Q000166:cytology / Q000528:radiation effects*; D009897:Optic Chiasm / Q000166:cytology* / Q000528:radiation effects; D011827:Radiation; D011833:Radiation Injuries, Experimental / Q000378:metabolism / Q000473:pathology*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D043583:Nucleoside-Triphosphatase