The effect of a heterocyclic amine, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), on tyrosine hydroxylase mRNA in PC12h cells.

The effects of a naturally occurring heterocyclic amine, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indol (Trp-P-1), on tyrosine hydroxylase (TH) mRNA levels were examined in PC12h cells using Northern blot analysis. Dose-dependency of Trp-P-1 for 24 h incubation gave biphasic results; 0.1 microM Trp-P-1 enhanced and 10 microM Trp-P-1 reduced TH mRNA levels. These effects were faded out in 48 h. One hundred microM Trp-P-1 caused the almost complete abolishment of TH mRNA expression as well as cell death. These results suggest the possibility that lower dose of Trp-P-1 might function as a trophic factor in contrast to neurotoxic effect in higher doses.