Enhancement of endothelial nitric oxide synthase production reverses vascular dysfunction and inflammation in the hindlimbs of a rat model of diabetes.
OBJECTIVE
Reduced bioavailability of nitric oxide (NO) is a hallmark of diabetes mellitus-induced vascular complications. In the present study we investigated whether a pharmacological increase of endothelial NO synthase (eNOS) production can restore the impaired hindlimb flow in a rat model of severe diabetes.


METHODS
A model of diabetes mellitus was induced in male Sprague-Dawley rats by a single injection of streptozotozin. Rats were treated chronically with the eNOS transcription enhancer AVE3085 (10 mg [kg body weight](-1) day(-1); p.o.) or vehicle for 48 days and compared with controls. Endothelial function and arterial BP were investigated in vivo using an autoperfused hindlimb model and TIP-catheter measurement, respectively. Protein production of eNOS, total and phosphorylated vasodilator-stimulated phosphoprotein (VASP) were assessed in their quadriceps muscle tissue, whereas cyclic GMP (cGMP) concentrations were assessed in blood plasma. RNA levels of intracellular and vascular cell adhesion molecules (ICAM-1 and VCAM-1) were measured by real-time PCR.


RESULTS
Untreated diabetic rats showed significantly reduced quadriceps muscle contents of eNOS (-64%) and phosphorylated VASP (-26%) protein associated with impaired vascular function (maximum vasodilatation: -30%, p < 0.05) and enhanced production of ICAM-1 (+121%) and VCAM-1 (+156%). Chronic treatment with AVE3085 did not alter arterial BP or severe hyperglycaemia, but did lead to significantly increased production of eNOS (+95%), cGMP (+128%) and VASP phosphorylation (+65%) as well as to improved vascular function (+36%) associated with reduced production of ICAM-1 (-36%) and VCAM-1 (-58%).


CONCLUSIONS
In a rat model of severe diabetes, pharmacological enhancement of impaired eNOS production and NO-cGMP signalling by AVE3085 restores altered hindlimb blood flow and prevents vascular inflammation.
Riad
A
A
Department of Cardiology and Pneumology, Charité Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12206, Berlin, Germany.
Westermann
D
D
Van Linthout
S
S
Mohr
Z
Z
Uyulmaz
S
S
Becher
P M
PM
Rütten
H
H
Wohlfart
P
P
Peters
H
H
Schultheiss
H-P
HP
Tschöpe
C
C
D000818:Animals; D015815:Cell Adhesion Molecules / Q000378:metabolism; D006152:Cyclic GMP / Q000097:blood; D048909:Diabetes Complications / Q000097:blood / Q000201:enzymology* / Q000235:genetics; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000139:chemically induced / Q000201:enzymology* / Q000235:genetics; D005786:Gene Expression Regulation; D006614:Hindlimb / Q000098:blood supply / Q000201:enzymology*; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000150:complications / Q000201:enzymology / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D015227:Lipid Peroxidation; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013311:Streptozocin / Q000494:pharmacology; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism; D014652:Vascular Diseases / Q000097:blood / Q000150:complications / Q000201:enzymology* / Q000235:genetics; D000098662:Vasodilator-Stimulated Phosphoprotein
D015815:Cell Adhesion Molecules; D047908:Intracellular Signaling Peptides and Proteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; D019010:Vascular Cell Adhesion Molecule-1; D000098662:Vasodilator-Stimulated Phosphoprotein; D013311:Streptozocin; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D006152:Cyclic GMP