| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
In intact mice, significant reductions were detected in the number of neurons of mesencephalic nucleus (Me5) and trigeminal ganglion (TG), and primary afferent terminals in the trigeminal sensory nuclear complex (TSNC) after 360th postnatal day, as compared with those in 30-day-old mice. In tooth-extracted mice, we observed severe degeneration of the inferior alveolar nerve (IAN) on day 40, and significant decrease in the number of Me5 and TG neurons from 60th to 360th postnatal day on the tooth-extracted side. Primary afferent terminals diminished severely in the TSNC were also observed on the tooth-extracted side.
In various areas of the central nervous system (CNS) acidic FGF (aFGF) was found to exist by the 10th postnatal day in astrocytes, and its level was gradually increased, while steady state levels of basic FGF, which appeared in neurons, were observed throughout experiments. While, any distinct changes in their levels, associated, with the reduction in the masticatory sensory neurons in aged mice, could not be detected. So, it was next hypothesized that the peripheral disability may result in the neuronal reduction, because severe degeneration of the ipsilateral IAN in the tooth-extracted mouse was certainly detected prior to a decrease in the number of Me5 and TG neurons in tooth-extracted mice. Expectedly, single injection of aFGF into the tooth-extracted socket restored the Me5, TG neurons and the primary afferent terminals of the TSNC affected by the tooth-extraction.
We additionally found a specific but more widespread distribution of proliferating cells in the adult mouse CNS. Although we can not explain the differentiation of all proliferating cells, thus neuro- and glio- genesis might be associated with a specific but hitherto role of plasticity and regeneration in the CNS.
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