Neurotransmitter — Shifts in Cerebro — Organic Processes

There is an enormous reduction in homovanillinic acid (HVA) and 5-hydroxyindol-acetic acid (5-HIAA) in the spinal fluid (CSF) of Parkinson patients. L-dopa and HVA are, however, present in large quantities in the CSF of treated patients, especially when the medication contains L-dopa. This correlates well with the high yield of HVA. There is no trace of L-dopa in the CSF, when it is not administered. In the discontinuance of treatment there is no increase of CSF — HVA even during the administration of probenecid, while the 5-HIAA concentration increases continuously. If the treatment is pursued in its original form, the probenecid test shows an enormous increase of HVA and 5-HIAA with predominance of HVA particularly in those patients receiving L-dopa. The ratio HVA/5-HIAA of healthy persons (1, 5) is however not attained even after 2 4 hours. It follows that treatment with L-dopa produces an increase and discontinuance a decrease of the HVA/5-HIAA quotients.