Normalization of tyrosine hydroxylase activity in vivo in the striatum of transgenic mice carrying human tyrosine hydroxylase gene: a microdialysis study.

Using a microdialysis method, we observed a similar steady-state L-3,4-dihydroxyphenylalanine accumulation in the striatum of transgenic mice carrying the human tyrosine hydroxylase (TH) gene after NSD-1015 perfusion (10(-4) M) as compared to nontransgenic mice. Basal extracellular levels of 3,4-dihydroxyphenylacetic acid before the perfusion of NSD-1015 were also comparable in both transgenic and non-transgenic striata. The results suggest that the in vivo activity of TH in the striatum of transgenic mice was retained to the normal level by some regulatory mechanism(s) in spite of the increased expression of the enzyme protein.