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Transmitter‐Like Release of Endogenous 3,4‐Dihydroxyphenylalanine from Rat Striatal Slices
Author(s) -
Goshima Y.,
Kubo T.,
Misu Y.
Publication year - 1988
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.1471-4159.1988.tb02470.x
Subject(s) - tetrodotoxin , stimulation , dihydroxyphenylalanine , dopamine , chemistry , endogeny , tyrosine , endocrinology , medicine , biophysics , biology , biochemistry
Biphasic electrical field stimulation (0.5–5 Hz, 2 ms, 25 V, 3 min) and high K + (10–30 mM , 5 min) released endogenous 3,4‐dihydroxyphenylalanine (DOPA) from superfused rat striatal slices. Characteristics of the DOPA release were compared with those of 3,4‐dihydroxyphenylethylamine (dopamine, DA). Electrical stimulation at 2 Hz evoked DOPA and DA over similar time courses, α‐Methyl‐ p ‐tyrosine (0.2 m M ) markedly reduced release of DOPA but not of DA. Maximal release (0.3 pmol) of DOPA was obtained at 2 Hz and at 15 m M K + . The impulse‐evoked release of DOPA and DA was completely tetrodotoxin (0.3 μM) sensitive and Ca 2+ dependent and the 15 m M K + ‐evoked release was also Ca 2+ dependent. On l‐[3,5‐ 3 H]tyrosine (1 μ M ) superfusion, high K + (15 and 60 m M ) released DOPA and DA together with concentration‐dependent decreases in tyrosine 3‐monooxygenase (EC 1.14.16.2) activity as indicated by [ 3 H]H 2 O formation, followed by concentration‐dependent increases after DOPA and DA release ended. These findings suggest that striatal DOPA is released by a Ca 2+ ‐dependent excitation‐secretion coupling process similar to that involved in transmitter release.