Characterization of L-DOPA transport in cultured rat and mouse astrocytes

✍ Scribed by M.J. Tsai; E.H.Y. Lee

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 583 KB
• Volume: 43
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/(sici)1097-4547(19960215)43:4<490::aid-jnr10>3.0.co;2-6

✦ Synopsis

The present work studied the transport of L-DOPA in cultured rat and mouse astrocytes. Results indicated that the uptake of L-[14C]DOPA in both rat and mouse astrocytes was Na+ independent and temperature sensitive. It was mediated by a carrier-mediated mechanism with K, values of 36 and 60.3 pM, and V,,, values of 2.4 and 1.9 nmollminlmg protein for rat and mouse cells, respectively. L-DOPA uptake was potently inhibited by aromatic or branched-chain amino acids. Interestingly, the release of intracellular L-[ 14C]DOPA was also trans stimulated by competitors that affect L-DOPA uptake. The 14C recovered in the 2-min uptake process was identified as L-[14C]DOPA. However, [14C]dopamine (DA) was also detected in both rat and mouse astrocytes after 30 min L-DOPA incubation, indicating the existence of aromatic L-amino acid decarboxylase (AADC). Taken together, L-DOPA was uphill transported into rat and mouse astrocytes by a Na + -independent exchanger with preference for aromatic and branchedchain amino acids. Rat astrocytes possessed higher affinity for L-DOPA uptake than mouse astrocytes. Both cells synthesized DA from exogenous L-DOPA. Thus, astrocytes serve not only as a temporary storage site for L-DOPA but also as a DA-producing machinery. These results may be of particular importance to parkinsonian patients under L-DOPA medication.