Gene Expression of Aromatic L-Amino Acid Decarboxylase mRNA in the Kidney of Normotensive and Hypertensive Rats

Peripheral dopamine (DA) synthesis and release increase during hypertensive stage of spontaneously hypertensive rats (SHR). DA is generated from 3, 4-dihydroxyphenylalanine by L-amino acid decarboxylase (AADC). We have studies urinary DA and DA metabolites and the gene expression of neuron and non-neuron specific AADC mRNA in the kidney of SHR. Compared to Wister-Kyoto rats (WKY), there was an increased urinary free DA and DOPAC excretions in 8 and 12 week-old SHR. At the age of 16 weeks, the difference in free DA excretion between SHR and WKY rats disappeared, although the urinary DOPAC excretion remained significantly higher in SHR, but urinary HVA excretion did not differ from WKY rats. The expression of the neuron specific AADC mRNA in the kidney of SHR and WKY rats was not detected, but the non-neuron specific AADC mRNA in the kidney of SHR and WKY rats was detected. The gene expression of the non-neuron specific AADC mRNA tended to decrease with age in SHR. The results suggest that a decrease in renal DA production with age may be caused by diminished expression of non-neuron specific AADC mRNA in kidney. (Hypertens Res 1995; 18 Suppl. I: S179-S181)