Endogenous proteolytic activity in a rat model of spontaneous cerebral stroke.
We evaluated the expression of two extra-cellular protease systems in a model of spontaneous cerebrovascular pathology: spontaneously hypertensive stroke-prone rats (SHRSP). The appearance of brain damage in individual animals was imaged and followed by means of magnetic resonance imaging (MRI). In situ zymography of brain slices obtained 3 days after the appearance of brain damage showed an increase in plasminogen activator (PA)/plasmin activity that co-localised with the cerebral damage detected by MRI; there was also concomitant accumulation/activation of inflammatory cells in the damaged area. Proteolytic activity was inhibited by the urokinase-specific inhibitor amiloride but not by an antibody against tissue-type plasminogen activator (t-PA). SDS-PAGE zymography of brain extracts revealed the presence of 58 kDa plasminogen-dependent lysis areas in the ischemic and non-ischemic tissues, and a 33 kDa lysis area in ischemic tissue only. An antibody against t-PA inhibited the former, whereas the latter was inhibited by amiloride. The specific induction of urokinase-type plasminogen activator (u-PA) in the damaged tissue was further confirmed by the fact that both u-PA protein mass and mRNA were markedly increased in the damaged cerebral areas. Concomitant metalloproteinase-2 (MMP-2) activation was only observed in the damaged area. These data suggest that u-PA is expressed and selectively catalyses proteolysis in the injured area of spontaneous brain damage in SHRSP.
Department of Pharmacological Sciences, University of Milan, Via Balzaretti 9, Italy.
Luigi
L
Sironi
Anna
A
Maria Calvio
Stefano
S
Bellosta
Barbara
B
Lodetti
Uliano
U
Guerrini
Mara
M
Monetti
Elena
E
Tremoli
Luciana
L
Mussoni
D000818:Animals; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000032:analysis / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D011918:Rats, Inbred SHR; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020521:Stroke / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D010959:Tissue Plasminogen Activator / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism
D010450:Endopeptidases; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator; D020778:Matrix Metalloproteinase 2