Effect of pyridoxal phosphate deficiency on aromatic L-amino acid decarboxylase activity with L-DOPA and L-5-hydroxytryptophan as substrates in rats.
This paper describes the distribution of aromatic L-amino acid decarboxylase (AADC) activities in fourteen tissues (eight peripheral tissues and six brain regions) of semicarbazide (SC)-treated rats, using both L-DOPA and L-5-hydroxytryptophan (L-5-HTP) as substrates. The distribution of pyridoxal phosphate (PLP) was also measured in control and SC-treated rats. SC-treatment decreased the PLP concentration in all tissues (about 50-60% of control). AADC activities towards L-DOPA and L-5-HTP as substrates were also decreased significantly in almost all tissues of SC-treated rats. After the addition of exogenous PLP in vitro, AADC activities were recovered only partially in most tissues, but the recovery patterns were not parallel between L-DOPA and L-5-HTP as substrates. L-DOPA decarboxylase activity was more sensitive to PLP-deficiency than L-5-HTP decarboxylase activity in the same tissues. Serum AADC activities were decreased drastically using both L-DOPA and L-5-HTP as substrates. No serum AADC activity was detected in SC-treated rats using L-DOPA as substrate, but low activity was detected in the same sample using L-5-HTP as the substrate; both activities recovered completely after in vitro addition of 10 microM PLP in the incubation mixtures.
D006916:5-Hydroxytryptophan / Q000378:metabolism*; D000818:Animals; D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004296:Dopa Decarboxylase / Q000378:metabolism; D007980:Levodopa / Q000378:metabolism*; D008297:Male; D011732:Pyridoxal Phosphate / Q000172:deficiency / Q000378:metabolism*; D051381:Rats; D012663:Semicarbazides / Q000494:pharmacology; D014018:Tissue Distribution
D012663:Semicarbazides; D007980:Levodopa; D011732:Pyridoxal Phosphate; D006916:5-Hydroxytryptophan; D004296:Dopa Decarboxylase; D001142:Aromatic-L-Amino-Acid Decarboxylases