Marini AM, Lipsky RH, Schwartz JP, Kopin IJ. Accumulation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in cultured cerebellar astrocytes.
J Neurochem 1992;
58:1250-8. [PMID:
1548462 DOI:
10.1111/j.1471-4159.1992.tb11336.x]
[Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cultured cerebellar astrocytes rapidly accumulate 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) from the incubation medium, reaching a plateau within 10 min, whereas within that time negligible amounts of 1-methyl-4-phenylpyridinium (MPP+) have entered the astrocytes. MPTP accumulation is essentially independent of temperature and is proportional to extracellular concentration at steady state: The steady-state concentration achieved within these cells is about 50-fold higher at relatively low extracellular concentrations. MPTP appears to accumulate intracellularly within lysosomes, because lysosomotropic agents such as ammonium chloride and chloroquine markedly diminish the accumulation. Moreover, a proton gradient is required, because MPTP accumulation is abolished by the hydrogen ion antiporter monensin. Over an interval of several days, MPTP is converted to MPP+ intracellularly, with a concomitant decrease in medium MPTP and increase in medium MPP+. A constant, small but significant amount of MPP+ is retained intracellularly over a 72-h interval. Increasing the medium MPTP concentrations results in increased conversion of MPTP and enhanced intracellular retention of MPTP and MPP+. Neither MPTP nor MPP+ is neurotoxic to cultured cerebellar astrocytes as determined by cell counts and rate of conversion of MPTP to MPP+.
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