Membrane-bound proteases of the gerbil subfornical organ and choroid plexus: an enzyme histochemical study.
Using enzyme-histochemical methods, the membrane-bound peptidases, gamma-glutamyl transpeptidase (gamma-GTP), microsomal alanyl aminopeptidase (mAAP), glutamyl aminopeptidase (EAP), and dipeptidyl peptidase IV (DPP IV), were studied in microvessels of the gerbil subfornical organ (SFO), choroid plexus adjacent to the SFO, and the ependyma of brain ventricle walls in the vicinity of the SFO. Vessels and microvessels of gerbil SFO and choroid plexus were positive for gamma-GTP, mAAP, and EAP, but negative for DPP IV. Blood-brain barrier (BBB) microvessels in the surrounding brain tissue also showed positive reactions for gamma-GTP, mAAP, and EAP but a negative reaction for DPP IV. Both epithelial cells of the choroid plexus and ependymal cells of the ventricle walls were negative for all four studied enzymes. It is suggested that blood-borne peptide hormones which can be substrates for these membrane-bound proteases can be modulated by gamma-GTP, mAAP, and EAP, but not by DPP IV, when they come in contact with the plasma membrane of the endothelial cells of the vessels in gerbil SFO, choroid plexus, and surrounding brain tissue.
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Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City 73190.
De Bault
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D000626:Aminopeptidases / Q000378:metabolism; D000818:Animals; D001808:Blood Vessels / Q000201:enzymology; D001921:Brain / Q000098:blood supply / Q000201:enzymology; D018826:CD13 Antigens; D002831:Choroid Plexus / Q000098:blood supply* / Q000201:enzymology; D018819:Dipeptidyl Peptidase 4; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology; D005629:Frozen Sections; D005849:Gerbillinae; D043384:Glutamyl Aminopeptidase; D006651:Histocytochemistry; D010447:Peptide Hydrolases / Q000378:metabolism*; D013356:Subfornical Organ / Q000098:blood supply* / Q000201:enzymology; D005723:gamma-Glutamyltransferase / Q000378:metabolism
D005723:gamma-Glutamyltransferase; D010447:Peptide Hydrolases; D000626:Aminopeptidases; D018826:CD13 Antigens; D043384:Glutamyl Aminopeptidase; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D018819:Dipeptidyl Peptidase 4