| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1994: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1993: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
(1) Postsynaptic depolarization in induction of hippocampal long-term potentiation
Hippocampal long-term potentiation (LTP) was investigated using acute slice preparation. LTP induced with 1 Hz stimuli in Mg2+-free medium (1 Hz LTP) was shown to have a threshold for LTP around 2-3 stimuli ; and it occluded with tetanus-induced LTP,suggesting that it has a common mechanism with tetanus-induced LTP.One Hz LTP was blocked by application of GABA or GABAA receptor-specific agonist muscimol, suggesting that postsynaptic depolarization is essential in addition to unblock Mg2+ from NMDA receptor channels in induction of LTP.
(2) In vitro reconstruction of cortico-spinal tract in organotyic slice culture s stem.
When slices of the cerebral sensorimotor cortex and the spinal cord were cocultured for 14-21 days, massive connections were formed, which were visualized with biocytin, Dil (anterogradely) or HRP (retrogradely). Synaptic connections between cortical and spinal neurons were confirmed by el
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ectrophysiological studies, both extra- and intracellularly. Quantitative field potential study suggests that there was no topographical preference in synapse formation between forelimb (hindlimb) area and cervical (lumbar) cord but that cortico-spinal projection fiber preferred the dorsal to the ventral side in entering spinal gray matter.
(3) Nigrostriatal slice coculture preparation and toxicity of I-Benzyl-TIQ
1-Bn-TQ is one of the promising endogenous candidate toxin for causing Parkinson's disease. We applied I-Bn-TIQ) to the cocultured slice preparation of midbrain and striatum. This substance caused marked reduction of dopamine in the striatum. it also increased LDH concentration in culture medium, which suggests cell death, but it did not change LDH level in slice culture of the cerebral cortex, the cerebellum or the hippocampus, suggesting that its toxicity is specific to nigrostriatal system. It also caused degenerative morphological changes in tyrosine hydroxylase-positive cells in the midbrain. Less
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