The effects of continuous and single-dose radiation on choline uptake in organotypic tissue slice cultures of rabbit hippocampus.
The objective of the present study was to determine the time-dependent course of choline uptake in mature organotypic slice cultures of rabbit hippocampal formation and to assess the effects of continuous and single high-dose irradiation on choline uptake in cultivated slices in vitro. Transverse slices of hippocampus were dynamically incubated in a cerebrospinal fluid-like culture medium for 72 h. To study the changes in choline uptake longitudinally, the slice cultures were processed with 0.1 microM [3H]-choline, and tritium accumulation was counted. Two different gamma irradiation sources (125I seeds and a clinical 60Co source) were used as representative models of interstitial radiosurgery and other radiosurgical techniques. A total dose of approximately 6000 cGy was delivered to the brain slices in one session or in a continuous, relatively low-dose rate fashion, and their effects on high-affinity choline uptake were examined. In another set of experiments with 125I, 5 microM hemicholinium-3 was used in choline uptake procedures as a competitive high-affinity choline uptake inhibitor. The results can be summarized as follows: (1) in the control group of the hippocampal tissue culture, there was a significant increase in tritium accumulation values from 0 to 48 h and a decrease thereafter; (2) continuous 125I irradiation caused a highly significant depression of the accumulation of tritium compared to that observed in the control group throughout its application for 72 h; (3) there was no significant change in the accumulation of tritium in the slices after single high-dose rate irradiation with a 60Co source; and (4) 5 microM hemicholinium significantly depressed the accumulation of tritium in both the control and the 125I-irradiated groups, and there was no longer a difference between 125I-irradiated and control groups when both groups were treated with hemicholinium. These results demonstrate that the delivery of continuous but relatively low-dose rate gamma irradiation is more efficacious than single high-dose external irradiation on high-affinity choline uptake in hippocampal nervous tissue. The results also indicate that continuous irradiation specifically affected the high-affinity energy-dependent choline uptake mechanism, whereas nonspecific choline uptake did not seem to be disturbed.
Savas
A
A
Abteilung Stereotaktische Neurochirurgie, Neurochirurgische Klinik, Neurozentrum, Albert-Ludwigs-Universität Freiburg, Medizinische Fakultät, Germany. alisavas@anet.com.tr
Warnke
P C
PC
Ginap
T
T
Feuerstein
T J
TJ
Ostertag
C B
CB
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism / Q000528:radiation effects*; D002794:Choline / Q000378:metabolism*; D004307:Dose-Response Relationship, Radiation; D015536:Down-Regulation / Q000502:physiology / Q000528:radiation effects; D005260:Female; D005720:Gamma Rays / Q000009:adverse effects* / Q000627:therapeutic use; D006426:Hemicholinium 3 / Q000494:pharmacology; D006624:Hippocampus / Q000378:metabolism / Q000503:physiopathology / Q000528:radiation effects*; D008297:Male; D009474:Neurons / Q000378:metabolism / Q000528:radiation effects*; D014179:Neurotransmitter Uptake Inhibitors / Q000494:pharmacology; D009924:Organ Culture Techniques; D011817:Rabbits; D016634:Radiosurgery / Q000009:adverse effects*; D014316:Tritium / Q000378:metabolism
D002352:Carrier Proteins; D014179:Neurotransmitter Uptake Inhibitors; D014316:Tritium; D006426:Hemicholinium 3; D002794:Choline; D000109:Acetylcholine