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Phospholipid‐derived choline intermediates and acetylcholine synthesis in mouse brain synaptosomes
Author(s) -
Yavin E.,
Tanaka Y.,
Ando S.
Publication year - 1989
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.490240215
Subject(s) - choline , acetylcholine , phosphatidylcholine , phosphorylcholine , chemistry , synaptosome , lysophospholipase , phospholipid , biochemistry , endogeny , phospholipase , medicine , endocrinology , biology , in vitro , membrane , enzyme
Endogenous free choline levels and acetylcholine (ACh) synthesis in nerve terminals were investigated using cerebral cortical synaptosomes of C57BL/6 mice. Endogenous choline was produced at a rate tenfold faster than ACh to provide levels adequate for the formation of the latter. The combined pool size of the water‐soluble intermediates derived from phosphatidylcholine (PhC), such as glycerophosphorylcholine (GpCh) and phosphorylcholine (PCh), increased significantly during the first 10–15 min of incubation and was always higher than that of free choline. These results most likely indicate an effective degradation of PhC by the combined action of phospholipase A 2 /lysophospholipase, as well as by phospholipase C in synaptosomes. ACh synthesis proceeded at a constant rate in the presence or absence of exogenous free choline (0–10 μM) and was almost entirely abolished in the presence of 10 −6 M hemicholinium‐3. These results suggest that ACh is effectively synthesized by free choline generated in synaptosomes by a coupling mechanism involving the high‐affinity choline uptake system. No changes in the production rates of choline and ACh were observed between adult and aged mice.