Premium
β‐Hydroxybutyrate as a Precursor to the Acetyl Moiety of Acetylcholine
Author(s) -
Sterling Gerald H.,
McCafferty Mary R.,
O'Neill John J.
Publication year - 1981
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.1471-4159.1981.tb04675.x
Subject(s) - chemistry , metabolism , moiety , acetylcholine , biochemistry , citric acid cycle , enzyme , ketone bodies , medicine , endocrinology , stereochemistry , biology
— Rat brain cortex slices were incubated with 10 m m ‐glucose and trace amounts of [6‐ 3 H]glucose and [3‐ 14 C] β ‐hydroxybutyrate. The effects of (‐)‐hydroxycitrate, an inhibitor of ATP‐citrate lyase; methylmalonate, an inhibitor of β ‐hydroxybutyrate dehydrogenase; and increasing concentrations of unlabeled acetoacetate were examined. The incorporation of label into lactate, citrate, malate, and acetylcholine (ACh) was measured and 3 H: 14 C ratios calculated. Incorporation of [ 14 C] β ‐hydroxybutyrate into lactate was limited because of the low activity of gluconeogenic enzymes in brain, whereas incorporation of 14 C label into Krebs cycle intermediates and ACh was higher than in previous experiments with [ 3 H‐, 14 C]‐glucose. (–)‐Hydroxycitrate (5.0 m M ) reduced incorporation of [ 3 H]glucose and [ 14 C] β ‐hydroxybutyrate into ACh. In contrast, slices incubated with methylmalonate (1 m m ) showed a decrease in 14 C incorporation without appreciably affecting glucose metabolism. The effects of high concentrations of methylmalonate were nonselective and yielded a generalized decrease in metabolism. Acetoacetate (1 m m ) also produced a decreased 14 C incorporation into ACh and its precursors. At 10 m m , acetoacetate reduced 3 H and 14 C incorporation into ACh without substantially affecting total ACh content. From the results, it is suggested that in adult rats β ‐hydroxybutyrate can contribute to the acetyl moiety of ACh, possibly via the citrate cleavage pathway, though it is quantitatively less important than glucose and pyruvate. This contribution of ketone bodies could become significant should their concentration become abnormally high or glucose metabolism be reduced.