Effect of interferon-γ and LPS on tetrahydrobiopterin in rat PC 12 and human KNA cells

The first human phaeochromocytoma cell line KNA was tested with regard to stimulation of dopamine biosynthesis by nicotinamide adenine dinucleotide (NADH). Differently from rat phaeochromocytoma cells - clone PC12, where NADH increased dopamine biosynthesis significantly, no stimulation in KNA cells was found. NADH is effective on speeding up the formation of the active cofactor tetrahydrobiopterin by a recycling pathway via the dihydropteridinreductase system. Another way of formation of tetrahydrobiopterin is the induction of de novo synthesis by cytokines such as interferon-gamma or by lipopolysaccharide via activation of GTP cyclohydrolase I, as shown in macrophages. Neither rat PC12 nor human KNA cells showed in vitro a stimulation of tetrahydrobiopterin de novo synthesis by interferon-gamma and/or lipopolysaccharide.