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Enkephalin Metabolism by Microglia Aminopeptidase N (CD13)
Author(s) -
Lucius Ralph,
Sievers Jobst,
Mentlein Rolf
Publication year - 1995
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 - 10.1046/j.1471-4159.1995.64041841.x
Subject(s) - aminopeptidase , enkephalin , microglia , metabolism , chemistry , biochemistry , medicine , leucine , amino acid , inflammation , receptor , opioid
Rat microglia in culture showed a high capacity to degrade neuropeptides compared with other glial cells. Leu‐enkephalin was readily hydrolyzed to free tyrosine and Gly‐Gly‐Phe‐Leu. Inhibition experiments and immunostaining revealed that aminopeptidase N (CD13) on the surface of microglia was responsible for enkephalin cleavage. Endopeptidase‐24.11 (“enkephalinase”), angiotensin‐converting enzyme, or carboxypeptidases could not be detected on microglia. Aminopeptidase N activity in microglia was considerably higher than in rat peripheral monocytes and macrophages, which both also exhibited low endopeptidase 24.11 activities. Activity of aminopeptidase N was upregulated by culture of microglia on astrocytes and downregulated by exposure of microglia to lipopolysaccharide. The occurrence of aminopeptidase N on microglia is in line with the view that they originate from the monocytic lineage.