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Studies on a Possible Functional Coupling Between Presynaptic Acetylcholinesterase and High‐Affinity Choline Uptake in the Rat Brain
Author(s) -
Raiteri Maurizio,
Marchi Mario,
Caviglia Anna Maria
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.tb13076.x
Subject(s) - acetylcholine , choline , acetylcholinesterase , chemistry , synaptosome , cholinergic , biophysics , moiety , hydrolysis , stereochemistry , biochemistry , endocrinology , membrane , enzyme , biology
The relationships between presynaptic acetylcho‐linesterase (AChE) and high‐affinity choline uptake (HACU) were investigated using a monolayer of rat cortex synaptosomes in superfusion conditions. The following sets of experiments were performed: (a) determination of [ 3 H]choline ([ 3 H]Ch) uptake during superfusion with [ 3 H]Ch; (b) determination of [ 3 H]Ch uptake during superfusion with acetylcholine (ACh) tritiated in the Ch moiety; (c) evaluation of ACh hydrolysis during superfusion with ACh labelled in the acetate moiety; and (d) comparison of the uptake of [ 3 H]Ch generated by hydrolysis of [ 3 H]ACh with that occurring during superfusion with [ 3 H]Ch. Intact ACh was not taken up by superfused synaptosomes. The uptake of [ 3 H]Ch during superfusion with 1 or 0.1 μM [N‐methyl‐ 3 H] ACh was two‐thirds of that occurring during superfusion with the same concentrations of [ 3 H]Ch. The amount of [ 3 H]Ch produced by hydrolysis during 16 min of superfusion was of the amount passing through the synapto‐somal monolayer during 16 min of superfusion with [ 3 H]Ch. The results indicate that presynaptic AChE and HACU are located in close proximity to each other on the cholinergic terminal membrane, an observation suggesting the possibility of a functional coupling between the two mechanisms.