A Confocal Laser Scanning Microscopic Study on the Distribution and Fluorescent Intensity of NPY-IR in the Cerebral Cortex of the Head Irradiated Rats

Kim, Jong Joong; Chung, Yoon Young; Jeong, Young Wook

Abstract

The purpose of this study, the 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. Radiation was produced by the linear accelerator 6MV X-ray. The animals were categorized into control and experimental groups and we use 45 Sprague-Dawley rats weighing about 200 ~250 gm. The head areas of the animals were positioned within the radiation field of 15 cmx20 cm and with the radiation depth of 2 cm. Sodium chloral hydrate-anesthetized rats were exposed to the radiation with the dose rate of 240 cGy/min. The total dose was 1,800 cGy(rad). Animals were sacrificed on 2 hours, 5 hours, 1 day, 2 days, 3 days, 1 week, weeks, 3 weeks after brain irradiation. Using ABC immunohistochemistry, morphology and distribution of neuropeptide-Y immunoreactive neurons (NPY-IR)were studied on the cerebral cortex of the control and brain-irradiated rats. We used light and confocal laser scanning microscopy (CLSM). The following results were obtained : 1. On control group, NPY-IR neurons were found in all layers of the primary motor and sensory 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 after X-irradiation, decreased number of NPY-IR neurons were detected in the primary motor and sensory cerebral cortex of the rats. Also shrunken and transformed NPY-IR neurons were detected in the primary motor and sensory cerebral cortex of the rats. 3. On 1 day, 2 days, 3 days after X-irradiation, morphology and distribution of NPY-IR neurons in the primary motor and sensory cerebral cortex was generally restored. 4. On 1 week, 2 weeks, 3 weeks after X-irradiation, morphology and distribution of NPY-IR neurons in the primary motor and sensory cerebral cortex was almost similar to control group. 5. In optical serial section analysis of NPY-IR neurons, high intensity of immunofluorescence 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) were observed in a part of 6, 7 sections of the control and all irradiated groups. 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.