Mitochondrial toxin inhibition of [3H]dopamine uptake into rat striatal synaptosomes

William F. Maragos, Jun Zhu, M. Dathan Chesnut, Linda P. Dwoskin

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Administration of the mitochondrial inhibitors malonate and 3-nitropropionic acid (3-NP) to rats provides useful models of Huntington's disease. Exposure to these inhibitors has been shown to result in increased extracellular concentrations of striatal dopamine (DA), which is neurotoxic at high concentrations. The cause of this increase is unknown. The purpose of this study was to determine whether mitochondrial inhibition alters dopamine transporter (DAT) function. Striatal synaptosomes were incubated in the presence of several structurally unrelated inhibitors of mitochondrial Complexes I, II, and IV, and [3H]DA uptake was measured. Although all of the toxins inhibited [3H]DA uptake, there was a large variation in their inhibitory potencies, the rank order being rotenone≫cyanide>azide>3-NP≫malonate. Examination of the kinetic parameters of [3H]DA uptake revealed that inhibition was due to a reduction in maximum velocity (Vmax), with no change in affinity (Km). The addition of either ATP or of ADP plus Pi to synaptosomes treated with 3-NP, or of the reactive oxygen species spin trap α-phenyl-N-tert-butyl nitrone to synaptosomes exposed to either malonate or cyanide failed to prevent mitochondrial toxin-induced inhibition of DAT function. The lack of effect of high energy substrates or of a free radical scavenger suggests that the mechanism by which extracellular DA is increased by several mitochondrial toxins involves factors other than mitochondrial ATP production or oxidative stress. Taken together, the results suggest that one mechanism whereby mitochondrial toxins increase extracellular concentrations of DA is via interaction with the DAT at a site other than the substrate site, i.e. noncompetitive inhibition of the DAT.

Original languageEnglish
Pages (from-to)1499-1505
Number of pages7
JournalBiochemical Pharmacology
Volume63
Issue number8
DOIs
StatePublished - Apr 15 2002

Bibliographical note

Funding Information:
This work was supported by NIH Grants NS01941 (W.F.M.), DA00399 (L.P.D.), and DA13519 (L.P.D.).

Keywords

  • 3-Nitropropionic acid
  • Dopamine transporter
  • Huntington's disease
  • Malonate
  • Rotenone
  • Striatum

ASJC Scopus subject areas

  • Biochemistry
  • Pharmacology

Fingerprint

Dive into the research topics of 'Mitochondrial toxin inhibition of [3H]dopamine uptake into rat striatal synaptosomes'. Together they form a unique fingerprint.

Cite this