Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
Board

Materials

Animals:
Four groups of male C57BL/6N mice having different ages (6, 10, 28 and 52 weeks after birth) were used. The mice had been purchased from Charles River Japan Inc. These groups were then housed in plastic and steel cages in Laboratory for Experimental Animals, Kanazawa University, fed a standard laboratory diet and had free access to drinking water during more then 1 week prior to administration. The five mice were used in each group.

Injected multitracer solution:
A no-carrier-added multitracer solution was obtained from an Ag (purity: more than 99.99%) target irradiated by heavy-ion beam in RIKEN Ring Cyclotron. The multitracer solution was prepared according to the method of Ambe et al (1,2) in Radioisotope Center, Kanazawa University. The solution contains 12 radioisotopes of 10 elements at 3 weeks after cyclotron bombardment. For mouse injection, the physiological saline solution (0.001N HCl, pH 2-3) containing the radioactive multitracer was finally prepared.

Method
An appropriate amount (0.2ml) of the multitracer solution was intraperitoneally injected into each mice. At 48 hr after i.p. injection, the mice were sacrificed under ether anesthesia and about 0.2ml blood was collected in a test tube. After this, brain were excised and separated into 7 regions(corpus striatum, cerebellum, cerebral cortex, hippocampus, midbrain, olfactory bulb, and pons and medulla)(Fig. 1). These separated regions were weighed immediately and freeze-dried. The dried samples were measured by gamma-ray spectrometry with pure Ge semi-conductor detectors against an appropriate standard to obtain "the percentage of injected dose per gram of the separated region" for different tracers, which was called as regional cerebral uptake rate (%dose/g of region). We took care of weighing the regional samples to avoid adhesive water without their upper estimation.

Fig.1. Sagittal and Coronal section of the mouse brain and the 7 separated regions in this experiment.

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