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Investigation of Dopamine Content, Synthesis, and Release in the Rabbit Retina In Vitro: I. Effects of Dopamine Precursors, Reserpine, Amphetamine, and l‐DOPA Decarboxylase and Monoamine Oxidase Inhibitors
Author(s) -
Ofori Senyo,
Bretton Christine,
Hof Patrick,
Schorderet Michel
Publication year - 1986
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1986.tb00740.x
Subject(s) - reserpine , dopamine , amphetamine , monoamine oxidase , chemistry , monoamine neurotransmitter , pharmacology , in vitro , endocrinology , medicine , biochemistry , enzyme , serotonin , receptor
The basal catecholamine content of rabbit retina was determined by liquid chromatography with electrochemical detection (LC‐EC) and 3,4‐dihydroxyphenyl‐ethylamine (dopamine, DA) found to be the major catecholamine. The immediate DA precursor, 3,4‐dihydrophenylalanine (l‐DOPA), and the metabolite, 3,4‐dihydroxyphenylacetic acid (DOPAC), were also detected at about 2.8% and 17% of DA levels, respectively. When added exogenously, l‐tyrosine did not increase the rate of DA synthesis over the basal level. In contrast, exogenous l‐DOPA led to a 3.5‐fold increase in DA, and to a 20‐fold increase in DOPAC content. The monoamine oxidase inhibitors par‐gyline and (‐)‐deprenyl differentially affected the degradation of DA, since 100 μ M pargyline was apparently more effective than 100 μ M (‐)‐deprenyl. Reserpine and (±)‐amphetamine each induced a Ca 2+ ‐independent decrease of DA stores. The separate actions of reserpine and (±)‐amphetamine in lowering tissue DA levels were additive, suggesting two separate pools of DA available for release from presynaptic stores. The present study demonstrates that the LC‐EC technique may be used to investigate the modulation of the synthesis and release of retinal DA in vitro, without the prior uptake of radiolabelled transmitter.