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KMID : 0377220000250020007
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Medical Journal of Chosun Univercity
2000 Volume.25 No. 2 p.7 ~ p.21
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Immunohistochemical Study on the Neyropeptide-Y Immunoreative Neurons in the Cerebral Cortex of the Brain-Irradiated Rat
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Lee Sang-Wook
Kim Jong-Joong
Chung Yoon-Young
Chung Jong-Dal
Oh Yoon-Kyeong
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Abstract
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Background and Objectives : Severe irradiation on the cerebral cortex of the human and animals may result in functional alterations of central nervous system. The purpose of this study, the irradiation effects on the cerebral cortex of the rats after brain irradiation was to investigate the change of distribution and morphology of neuropeptide-Y(NPY) neurons.
Materials and Methods : Radiation was produced by the linear accelerator 6MV X-ray, and the animals were categorized into control and experimental groups and we use 45 Sprague-Dawley rats weighing about 200~250gm. The head areas of the animals were positioned within the radiation field of 12㎝ × 20㎝ and with the radiation depth of 1.5㎝. Sodium chloral hydrate-anesthetized rats were exposed to the radiation with the dose rate of 240 cGy/min. The total dose was 1800 cGy. Animals were sacrificed on 2 hours, 5 hours, 1 day, 3 days, 7days after brain irradiation. Under anesthesia, animals were perfused with 4% paraformaldehyde-1% glutaraldehyde solution. On one or two hours after the perfusion, brain were taken out and refixed over night in the same fixative. Using ABC immunohistochemistry, morphology and distribution of neuropeptide-Y immunoractive(NPY-IR) neurons were studied on the cerebral cortex of the control and brain-irradiated rats. We used light, transmission electron and confocal laser scanning microscope.
Results : The following results were obtained : 1. On control group, NPY-IR neurons were found in all layers of the primary sensory and motor cerebral cortex, and the NPY-IR neurons were concentrated within the layer II, III, IV, V and VI. The typical NPY-IR perikarya was bipolar and multipolar shape. 2. On 2 hours, 5 hours, 1 day after X-irradiation, decreased number of NPY-IR neurons were detected in the primary sensory and motor cerebral cortex of the rats. Also shrunken and transformed NPY-IR neurons were detected in the primary sensory and motor cerebral cortex of the rats. 3. On 3 days and 7 days after X-irradiation, morphology and distribution of NPY-IR neurons in the primary sensory and motor cerebral cortex was generally restored. 4. In optical serial section analysis of NPY-IR neurons, high fluorescence intensity were observed in a part of the 8~11 sections of the control and all irradiated groups. In optical single section analysis of NPY-IR neurons, red color(high fluorescence intensity) was observed in a part of 6, 7 sections of the control and all irradiated groups. 5. By electron microscopy, NPY-IR neurons on 2 hours, 5 hours, 1 day after X-irradiation rats exhibited severe alterations of their organelles concerning intracellular material transport ; such as disappearance of microvilli and basal infoldings, reduction of invaginating pits on the basal and apical plasma membranes, reduction of transformed vesicles and shrunken Golgi complexes, etc.
Conclusion : From the above results, it was concluded that the release of neurotransmitters and transcapillary leakage of blood substance were occurred on 2 hours, 5 hours, 1 day after X-irradiation, but the condition was generally restored on 3 days and 7 days following X-irradiation.
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KEYWORD
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X-irradiation, primary sensory and motor cortex, neuropeptide-Y
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