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Staining, Tracing, and Imaging Techniques

開催日 2014/9/12
時間 14:00 - 15:00
会場 Poster / Exhibition(Event Hall B)

短時間撮像シークエンスを用いたin vivoマンガン増強MRI法の方法確立
A new sequence method of manganese enhanced MRI in vivo

  • P2-390
  • 吉川 弥里 / Misato Yoshikawa:1 高島 明彦 / Akihiko Takashima:1 
  • 1:独立行政法人国立長寿医療研究センター 分子基盤研究部 / Dept Aging Neurobiol, National Center for Geriatrics and Gerontology, Aichi, Japan 

To study brain activity in vivo, manganese enhanced MRI (MEMRI) is one of the simple and easier technique for small animal such as mouse and rat. Mn ion, which is enhancer of MR image, enters into activated neurons through voltage-gated calcium channel. In the result, activated brain regions are visualized by T1-weighted MR images. Although manganese is known as cofactor of enzymes, high dose application of manganese reduces an activity in behavioral task.
Here we determined Mn concentration and MRI sequence under 4.7T MRI scanner for obtaining neural activity by MEMRI. C57BL/6N mice (5-8 months old) are used for all experiments. To determine appropriate dose of MnCl2 for intraperitoneal injection, we measured spontaneous locomotor activity at 30 min after intraperitoneal injection of different concentrations of MnCl2 (0, 20, 40, 80 mg/kg). Until 20 mg/kg MnCl2 injection, locomoter activity showed no significant difference compared with vehicle injected group, but more MnCl2 injection than 20 mg/kg reduced locomoter activity. These results suggest that 20 mg/kg MnCl2 injection is the maximum concentration, which does not affect to locomoter activity. Under this condition, we attempted to use Fast Imaging with Steady State Precession (FISP) sequence, shorten total scanning time compare with the others for MEMRI. MR images were taken 4h after injection of MnCl2, in which most manganese incorporate into cells from blood. FISP could obtain Mn signals as T1-weighted MR images. Then, we compared brain images in new environment (open-field) and in home cage. Mn signals of mice in new environment enhanced in brain regions of accumbens, motor cortex and hippocampus, and signal intensity of motor cortex significantly correlate with locomoter activity, suggesting that this protocol for MEMRI is able to determine a quantitative analysis of neuronal activity during behavioral task.

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