The subcellular distribution of acetylcholine, choline acetyltransferase and acetyl cholinesterase in nerve tissue

Pharmacological properties of rat brain fatty acid amidohydrolase in different subcellular fractions using palmitoylethanolamide as substrate

In the present study, the pharmacological properties of fatty acid amide hydrolase (FAAH) in subcellular fractions of rat brain were investigated using palmitoylethanolamide (PEA) and arachidonyl ethanolamide (anandamide, AEA) as substrates. FAAH hydrolysed [(3)H]PEA in crude homogenates with median K(m) and V(max) values of 2.9 microM and 2.14 nmol.(mg protein)(-1).min(-1), respectively. [(3)H]PEA hydrolysis was inhibited both by non-radioactive AEA (with a K(i) value very similar to the K(m) value for [(3)H]AEA as substrate using the same assay) and by R(-)ibuprofen (mixed-type inhibition K(i) and K'(i) values 88 and 720 microM, respectively). FAAH activity towards both [(3)H]PEA and [(3) myelin = cytosol, but there were no differences between the relative activities towards the two substrates in any of the fractions. [(3)H]PEA hydrolysis in mitochondrial, myelin, microsomal, and synaptosomal fractions was inhibited by oleyl trifluoromethylketone, phenylmethylsulphonyl fluoride, and the R(-)- and S(+)-enantiomers of the nonsteroidal anti-inflammatory drug ibuprofen, with mean IC(50) values in the ranges 0.028-0.041, 0.37-0.52, 67-110, and 130-260 microM, respectively. It is concluded that the pharmacological properties of FAAH in the different subcellular fractions are very similar.

Studies on synaptic vesicles in mammalian brain characterization of highly purified synaptic vesicles from bovine cerebral cortex

Synaptic vesicles have been isolated from bovine cerebral cortex by sequential differential and density gradient centrifugations followed by chromatography on a Sepharose 6B column. We have studied the morphology, enzymatic markers, neurotransmitter and ATP contents and protein composition of the vesicles. The specific contents of acetylcholine, gamma-aminobutyric acid, aspartate, glutamate and catecholamines were 4--8-fold higher in the vesicle fraction compared to the crude synaptosomal pellet. Electron micrographs of the vesicle preparation showed enrichment of vesicular material with an average diameter of 50 nm. The purity of the preparation was assessed by the very low activities of enzymatic markers of cellular membranes and cytosol components. Some Ca--Mg-activated ATPase activity was detected in the vesicle preparations, but its content relative to the neurotransmitters fell on chromatography, suggesting that this activity may be partially contributed by non-synaptic vesicle components, such as small microsomes. The isolated synaptic vesicles were solubilized with 1% sodium dodecyl sulfate and subjected to polyacrylamide gel electrophoresis. The major Coomassie blue stained bands observed with apparent molecular weights of 160,000 and 55,000 were enriched in parallel to the increase in purity of the preparation.

Acetylcholinesterase isozymes in developing mouse tissues

Several isozymes of acetylcholinesterase are separated by 10% acrylamide gel electrophoresis of mouse blood, brain, heart, muscle and tongue tissues. Two isozymes migrating near the origin are described which show changes in relative activity during development. The faster of the two bands is proportionately higher in concentration in embryonic tissues and is highly specific for the acetylthiocholine iodide substrate. This isozyme corresponds to the erythrocyte membrane AChE in electrophortic mobility and substrate specificity. The slower of the two bands is predominant in adult tissues and exhibits considerable cross reaction with the butyrylthiocholine iodide substrate. During embryonic and postnatal developmental stages there is a gradual shift from the faster migrating isozyme toward a predominance of the slower migrating isozyme.