Download An Endothelin Type A Receptor Antagonist Reverses Upregulated

An Endothelin Type A Receptor
Antagonist Reverses Upregulated VEGF
and ICAM-1 Levels in StreptozotocinInduced Diabetic Rat Retina
Koichi Masuzawa, Katsutoshi Goto, Subrina Jesmin, Seiji Maeda,
Takashi Miyauchi, Yuichi Kaji, Tetsuro Oshika, Sadao Hori
Current Eye Research, 31:79–89, 2006
Prof. Kim, Y.S. /R3 Moon, Soo-youn
Introduction
• Diabetic retinopathy (DR)
– Cause of blindness
– Upregulation of vascular endothelial growth factor (VEGF),
leukostasis and endothelin (ET) -1
• VEGF
– Pivotal role in the pathogenesis of proliferative DR
– Capillary nonperfusion, vascular permeability accentuation,
and vascular proliferation
• Leukostasis (leukocyte adhesion)
– Important contributing factor to the pathogenesis of DR
– Capillary obstruction
– Intercellular adhesion molecule-1 (ICAM-1)
• Takagi et al.
– Upregulation of ET-1 in the streptozotocin (STZ)-induced
diabetic rat retina - one of the factors to decrease the
retinal blood flow in early DR
• Objectives
– Effect of ETA receptor antagonist (TA-0201; 1 mg/kg/day)
on the expressions of VEGF and ICAM-1 in rat diabetic
retina
Materials and Methods
• Animals and drug treatment
– Male, 10-week-old, Sprague-Dawley rats
– Single 70mg/kg IP injection of streptozotocin
– Diabetic animals
• ETA receptor selective antagonist (TA-0201; Tanabe Seiyaku
Co., Ltd., Saitama, Japan) at a dose of 1 mg/kg/day for a
total of 4 weeks (DM+TA-0201)
• Vehicle group was treated with physiological saline only
(DM+vehicle)
– Non-DM control
• Enzyme-linked immunosorbent assay for VEGF and
ICAM-1 protein levels
•
•
•
•
Immunohistochemistry – VEGF and ET-1
VEGF gene expression by rt-PCR
First-strand cDNA synthesis
Real-time PCR analysis
– cDNA
– VEGF/β-actin
• Retinal leukostasis quantification
– Fluorescein-isothiocyanate (FITC)-labeled concanavalin A
lectin (ConA) (Vector Laboratories, Burlingame,CA,USA)
• Histopathology examination
• FITC-dextran angiography
• Statistical analysis
Results
Characteristics of nondiabetic & diabetic rats
Non-DM
control
DM+vehicle
DM+TA-0201
Body weight (g)
496.4±51.2
345.1±35.1∗
352.9±36.3∗
Blood glucose
(mg/dl)
117.3±10.7
539.2±31.9†
528.7±39.0†
Plasma insulin
(ng/ml)
7.94±2.44
0.32±0.30
0.24±0.17
Values are means ± SD. Significantly different from non-DM control:
∗p<0.01 and †p<0.01.
Expression of VEGF
Gene expression
and protein levels
Immunohistochemical findings
Expression of ET-1
Immunohistochemical findings
Expression of ICAM-1 in retina and retinal leukostasis
ICAM-1 protein levels
Leukocyte adhesion in the
retinal arterioles
Fluorescence microscopic
images
Morphological and angiographic changes
H&E stain & FITC-dextran angiography
Conclusion
• ETA receptor antagonist – useful in preventing the
progression of diabetic retinopathy
– suppressing the increase in VEGF and ICAM-1 levels as
well as leukostasis in morphologically intact diabetic retina