Enhanced green fluorescent protein expression in brain tissues of green nude mice

Objective To analyze the expression levels of enhanced green fluorescent protein (EGFP) in brain tissues of EGFP transgenic mice for providing the basis of brain transplantation in green nude mice. Methods Foxn1nu.B6-CAG-EGFP/SU green nude mice were chosen; the EGFP mRNA expression level in various organ tissues/cells and different parts of the brain were analyzed by semi-quantitation real time-PCR or quantitative PCR (qPCR); fluorescence microscopy was used to detect the green fluorescence in main organ tissues and 12 brain coronal frozen tissues were directly observed to survey the patterns of EGFP expression. Furthermore, the EGFP protein expression and EGFP positive cells in different parts of brain were detected by fluorescence spectrophotometer assay and immunohistochemistry. Results The level of EGFP expression varied among main organs tissues/cells analyzed by semi-quantitation real time-PCR. The green fluorescence could be observed in 12 coronal frozen sections of brain with intensity differences under the fluorescence microscope, and the fluorescence intensity was higher in the cerebellar cortex, hippocampus and olfactory bulb tissue. As compared with those in the cerebral cortex tissue, the EGFP mRNA and protein expression levels in the cerebellum, hippocampus and olfactory bulb tissues were obviously higher showed by qPCR and fluorescence spectrophotometer assay. Meanwhile, the immunohistochemistry results showed that there were some cells which strongly expressed EGFP in the cerebellum, hippocampus and olfactory bulb tissues. Conclusions EGFP is positively expressed in the brain of green fluorescence nude mice, especially in the cerebellum, hippocampus and olfactory bulb tissues, which indicates that the brain may be useful for human cancer transplantation research. Key words: Green nude mouse; Enhanced green fluorescent protein; Brain tissue