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Transmitter release by non‐receptor activation of the α‐subunit of guanine nucleotide regulatory protein in rat striatal slices
Author(s) -
Zelles T.,
Chernaeva L.,
Baranyi M.,
Déri Z.,
AdamVizi V.,
Vizi E. S.
Publication year - 1995
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490420212
Subject(s) - protein subunit , guanine , microbiology and biotechnology , guanine nucleotide exchange factor , nucleotide , g protein , chemistry , neuroscience , biology , genetics , gtpase , signal transduction , gene
The effects of 5 mM NaF + 10 μM AIC1 3 , a direct activator of guanine nucleotide‐binding proteins (G proteins), on the release of [ 3 H]dopamine ([ 3 H]DA), [ 3 H]gamma‐aminobutyric acid ([ 3 H]GABA), and [ 3 H]acethylcholine ([ 3 H]ACh) were investigated in slices of rat striatum. When the tissue was exposed to NaF + AIC1 3 the release of [ 3 H]DA, [ 3 H]GABA, and [ 3 H]ACh was enhanced significantly. In a calcium free solution the release of [ 3 H]GABA and [ 3 H]DA was increased by NaF + A1C1 3 much more than in the presence of [Ca 2+ ]. In slice preparations taken from reserpinized animals, in which the vesicular storage of [ 3 H]DA was therefore prevented, NaF + AIC1 3 had no effect on [ 3 H]DA release. HPLC analysis of the radioactivity of the perfusate showed that, in the presence of NaF + AICI 3 , the content of dihydroxyphenylacetic acid (DOPAC) in perfusate samples increased significantly, while in pargyliue‐treated animals only the DA content was increased. Inhibition of DA carriers by nomifensine or low temperature prevented the effect of NaF + AIC1 3 . N‐ethylmaleimide (NEM) preincubation did not modify the effect of NaF + AICl 3 on [ 3 H]DA release. Neomycin (0.1 mM), a phospholipase C (PLC) inhibitor, significantly decreased the effect of NaF + AlC1 3 on [ 3 H]DA and [ 3 H]GABA release. The internal concentration of Ca 2+ in synaptosomes was enhanced by NaF + AIC1 3 in normal solution. However, [Ca 2+ ] i was not influenced by NaF + AIC13 in Ca 2+ ‐free medium. It is concluded that a non‐receptor‐mediated activation, by NaF + AICl 3 , of the a‐subunit of a G protein, results in a [Ca 2+ ] o ,‐independent release of DA and GABA, but not that of ACh. © 1995 Wiley‐Liss, Inc.