-N-acetyl D-galactosaminidase in bulk separated neurons and neuropil from rat cerebral cortex

Acid hydrolase activity of cultured bovine oligodendrocytes

We measured the activity of several acid hydrolases of cultured oligodendrocytes prepared from adult bovine brain white matter to clarify the biochemical basis of bovine oligodendrocytes in vitro. Lysosomal enzyme activities were assayed by using 4-methylumbelliferyl glycosides as substrates. Lysosomal enzyme activities became higher at 8-11 days in vitro (DIV) than 4 DIV. The enrichment in acid hydrolase specific activities in oligodendrocytes may be associated with lysosomal origin of myelin-like membranes.

Lysosomal acid hydrolases in developing human brain regions

beta-D-Glucosidase, beta-D-glucosaminidase, acid phosphatase, and beta-D-galactosidase were monitored in the human foetal brain at different gestational periods. Glucosidase specific activity in all brain regions exhibits two peaks, at 8 g and 32 g foetal weights. Acid phosphatase exhibits very high specific activity in all brain regions at 5 g, but the cerebellar activity forms a peak at 220 g foetal weight, the midbrain at 135 g, and the spinal activity at 760 g. beta-D-Glucosaminidase has a peak at 220 g and 660 g in the midbrain, and beta-D-galactosidase specific activity is highest in the cortex and cerebellum in late gestation (neuronal differentiation phase). The midbrain medulla and the spinal cord show peak activity at 8 g and 220 g foetal weight. The results suggest an inter- and intraregional heterogeneity of acquisition for these enzymes in human brain ontogeny.

Cellular compartmentation of brain metabolism and its functional significance

This paper reviews work from our laboratory on the metabolism and interrelations of isolated neuronal and neuropil fractions. The cell preparations are evaluated according to criteria of yield, purity, and integrity. Differences in the levels of activity of six groups of enzymes, of glucose metabolism, amino-acid metabolism, transmitter metabolism, acid hydrolysis, alkaline hydrolysis, and carbonic anhydrase have been followed, and neuronal and glial marker enzymes are proposed. Lysosomes and their enzymes are concentrated in neuronal perikarya. Metabolically, although no major differences in glucose oxidation have been found, there is considerable evidence of compartmentation of amino acids and their metabolism. At short times after injection of 3H-lysine as precursor in vivo, neuronal incorporation is high as compared with neuropil; at longer times the ratio is reversed, and we interpret this as evidence for the presence of a rapidly labeling protein fraction present in the neuromal perikarya but subsequently transported out. Neuronal protein incorporation is suppressed in the visual but not the motor cortex of dark-reared rats and is switched on following exposure to light; there is evidence that the suppressed fraction of neuronal protein synthesis includes the rapidly labeling component. A model for neuronal-glial metabolic interaction and its state-dependence in response to changes in the organism's environment and behavior is sketched out.