5-lipoxygenase expression and activity in aorta from streptozotocin-induced diabetic rats.
We previously reported an activation of the 5-lipoxygenase pathway in aorta from streptozotocin-induced diabetic rats. The aim of this study was to investigate whether this activation was associated with an increased expression of 5-lipoxygenase, an increased cysteinyl leukotriene (CysLT) production in response to arachidonic acid or calcium ionophore A23187 and/or a hypersensitivity of the aorta to CysLTs in streptozotocin-induced diabetic rats. In aorta from diabetic and control rats, reverse transcriptase-PCR and western blot analysis with a specific 5-lipoxygenase antibody provided evidence for the presence of 5-lipoxygenase in aorta. However, the expression of 5-lipoxygenase was not significantly different between diabetic and control rats. Challenge by A23187 (10 microM) and arachidonic acid (10 microM and 0.1 mM) with or without A23187 (10 micromol/l) induced a significant increase of CysLT release (measured by enzyme immunoassay) that was in the same range in aorta from control and diabetic rats. In contrast, aortas from diabetic rats showed a greater sensitivity to LTC4 and LTD4 contractile effects. These data suggested that the activation of the 5-lipoxygenase pathway previously reported in streptozotocin-induced diabetic rats could be explained by an augmented sensitivity to CysLTs of the diabetic aorta.
Hardy
G
G
Laboratory of Pharmacology, Laboratory HP2, University of Medicine, F-38706 La Tronche, France.
Vergnaud
S
S
Lunardi
J
J
Peoc'h
M
M
Bessard
G
G
Stanke-Labesque
F
F
D000818:Animals; D001013:Aorta, Thoracic / Q000201:enzymology* / Q000503:physiopathology; D001094:Arachidonate 5-Lipoxygenase / Q000235:genetics* / Q000378:metabolism; D016718:Arachidonic Acid / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D017931:DNA Primers; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic; D066298:In Vitro Techniques; D007537:Isometric Contraction; D015289:Leukotrienes / Q000494:pharmacology*; D008297:Male; D009129:Muscle Tonus / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000201:enzymology / Q000503:physiopathology; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D015289:Leukotrienes; D016718:Arachidonic Acid; D000001:Calcimycin; D001094:Arachidonate 5-Lipoxygenase