Table 1. Serotonin and Dopamine Synthesis Rate in Homozygous 1473G and 1473C Mice.

	DOPA	5-HTP
Forebrain
1473C/C	1.30±0.26	0.79±0.04
1473G/G	1.26±0.25	0.48±0.02***
Midbrain/brain stem
1473C/C	0.78±0.16	1.45±0.07
1473G/G	0.94±0.17	1.27±0.09
Total
1473C/C	1.18±0.24	0.94±0.04
1473G/G	1.19±0.23	0.64±0.03***

^***p<0.001.

Brain tissue concentrations of 5-hydroxytryptophan (5-HTP; serotonin precursor) and dihydroxyphenylalanin (DOPA; dopamine precursor) were determined in experimentally naive male 1473G/G (n=5) and 1473C/C mice (n=5) that had been treated with the L-aromatic amino acid decarboxylase inhibitor NSD 1015 30 min before analysis. Concentrations of accumulated DOPA, representing dopamine synthesis, were undistinguishable between homozygous mice of both Tph2 alleles. Accumulated 5-HTP concentrations representing 5-HT synthesis were significantly lower by 40% in the forebrain (p<0.001) and insignificantly lower by 15% in the midbrain/brain stem of 1473G/G mice. The total 5-HTP brain content was significantly reduced by 30% (p<0.001). All data are presented as mean values±SEM. All stars represent p-values of significances between genotypes from unpaired t-tests.