Abstract
The D stereoisomer of dihydroxyphenyl alanine (D-DOPA) and its α-keto acid metabolite 3,4-dihydroxyphenylpyruvic acid (DHPPA), when infused into the striatum, significantly increased in vivo extracellular dopamine levels. Following D-DOPA administration, the cumulative increase in dopamine levels was 30% of the increase following L-DOPA; following DHPPA it was 11% that of L-DOPA. Rats with unilateral 6-hydroxydopamine-induced lesions of the substantia nigra demonstrated brisk contralateral turning following each compound. The turning, however, was delayed by 10-20 min and total turning was 40% less following D-DOPA and 57% less following DHPPA than it was following L-DOPA. These data indicate that exogenously administered D-DOPA can be metabolized in vivo within the brain to dopamine and suggest this may occur via a transamination pathway in which DHPPA is an intermediary metabolite. The possible relevance of these findings to the treatment of Parkinson's disease is discussed.
Original language | English |
---|---|
Pages (from-to) | 165-168 |
Number of pages | 4 |
Journal | Brain Research |
Volume | 718 |
Issue number | 1-2 |
DOIs | |
State | Published - Apr 29 1996 |
Keywords
- Catecholamine metabolism
- Cerebral microdialysis
- D-DOPA
- Dihydroxyphenylpyruvic acid
- L-DOPA
- Parkinson's disease