The effects of continuous and single-dose radiation on choline uptake in organotypic tissue slice cultures of rabbit hippocampus

Abstract

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.

Organotypic Culture Model of Pancreatic Cancer Demonstrates that Stromal Cells Modulate E-Cadherin, β-Catenin, and Ezrin Expression in Tumor Cells

“…Organotypic models have been used extensively in skin, esophageal, brain, and breast cancers, where they have helped in determining the mechanisms of tumor invasion, 4,7,23 the effect of drugs, 24 the impact of radiotherapy, 25 as well as normal physiological functions. 16,26 However, in pancreatic research, the use of 3D models has been limited.…”

Effects of Irradiation on the [Methyl-3H]Choline Uptake in the Human Prostate Cancer Cell Lines LNCaP and PC3

“…Several in vitro studies have shown alterations in the uptake of tracers in surviving tumor cells after irradiation or treatment with cytostatic drugs [17,28,36,38,41].…”

“…This indicates that the choline transport system is not affected directly by ionizing radiation e.g., by peroxidation of cell membrane components [38], as increasing doses should result in increasing membrane damage. Thus, the observed changes in choline uptake might be due to indirect effects on cellular signaling pathways like the phosphatidylinositol 3 kinase (PI3K) pathway [35] which could result in altered translocation of choline transporters to the plasma membrane [14].…”

In Vitro Models of Spinal Cord Injury

“…Some scientists use the OTS for the study of radiation effect on cell damage. By determining the timedependent course of choline uptake in mature organotypic slice cultures of rabbit and assessing the effects of continuous and single high-dose irradiation on choline uptake, the 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 nervous tissues [28].…”