OBJECTIVEIncreased vascular endothelial growth factor (VEGF) and VEGF receptor expression is the important biological response under shear stress, ischemia and hypoxia conditions. Mechanical vibration induced cochlea shear stress and trauma obviously upregulate VEGF and VEGF receptor 2 (VEGFR2) expression in the cochlea. To evaluate the possibility of VEGF varying the transport in blood-labyrinth barrier and blood-perilymphatic barrier.

METHODSEleven guinea pigs, male and female, weighing from 300 g to 900 g were kept under general anaesthesia with xylazine (16 mg/kg) and ketamine (60 mg/kg) for both drug delivery and MRI measurement. VEGF (6 ears) and phosphate-buffered saline (PBS, 5 ears) were delivered to the inner ear via the round window membrane (soaked in gelfoam). The T1 contrast agent gadodiamide (Gd-DTPA-BMA) chelated bound paramagnetic gadolinium was used as the inner ear barrier transportation tracer. A Bruker Biospec Avance 47/40 experimental MRI system with a magnetic field strength of 4. 7 Tesla and a 40 cm bore was used for the 2-dimensional cochlea MRI evaluation. The Paravision software was used for image intensity measurement and the Adobe Photoshop 6.0 software was used for image presentation.

RESULTSVEGF induced significant Gd uptake in the scala tympani and scala vestibuli, but had little effect on the uptake of Gd in the scala media.

CONCLUSIONSVEGF significantly increased the transportation of blood-perilymphatic barrier and adapted the inner ear for compensation and repair.

Animals ; Blood-Brain Barrier ; drug effects ; Blood-Retinal Barrier ; drug effects ; Ear, Inner ; drug effects ; metabolism ; Female ; Guinea Pigs ; Magnetic Resonance Imaging ; Male ; Vascular Endothelial Growth Factor A ; pharmacology

PURPOSE: Cancer-associated retinopathy is a paraneoplastic retinal degeneration which may primarily result from auto-immune mediated apoptosis. It has been hypothesized that high titer of auto-antibodies are able to cross the blood-retinal barrier (BRB) and to enter retinal cells to activate apoptotic pathway which has been already well-established. However, it still remains to be elucidated whether auto-antibodies could cross BRB in the retina. Herein, we demonstrated that intravenously administrated anti-recoverin antibodies could not pass through BRB and not lead to retinal cell death. METHODS: Anti-recoverin antibody was intravenously injected to C57BL/6 mice, which were sacrificed 1 and 7 days to obtain eye. Vascular endothelial growth factor was intravitreally injected to induce BRB breakdown, which was confirmed by fluorescein angiography and western blotting for zonula occludens (ZO)-1, ZO-2 and occludin. To investigate the location of anti-recoverin antibody in the retina, immunofluorescein was performed. The retinal toxicity of intravenous anti-recoverin antibody was evaluated by histological examination and transferase-mediated dUTP nick-end labeling. Immunofluorescein staining for glial fibrillary acidic protein was done to address glial activation as well. RESULTS: Intravenously administrated anti-recoverin antibodies were exclusively distributed on retinal vessels which were co-localized with CD31, and led to neither increase of glial fibrillary acidic protein expression, as an indicator of retinal stress, nor apoptotic retinal cell death. Moreover, even in the condition of vascular endothelial growth factor-induced BRB breakdown, anti-recoverin antibodies could not migrate across BRB and still remained on retinal vessels without retinal cytotoxicity. CONCLUSIONS: Our results suggest that high titer of intravascular anti-recoverin antibodies could not penetrate into the retina by themselves, and BRB breakdown mediated by dysregulation of tight junction might not be sufficient to allow anti-recoverin antibodies to pass through BRB.
Animals ; Antibodies/*administration & dosage/*metabolism ; Blood-Retinal Barrier/*metabolism ; Cell Death/drug effects ; Cells, Cultured ; Female ; Injections, Intravenous ; Mice ; Mice, Inbred C57BL ; Recoverin/*immunology ; Retina/cytology/drug effects ; Retinal Vessels/metabolism

To evaluate the effect of chlorogenic acid (CGA), a polyphenol abundant in coffee, on retinal vascular leakage in the rat model of diabetic retinopathy, Sprague-Dawley rats were divided into four groups: controls, streptozotocin-induced diabetic rats, and diabetic rats treated with 10 and 20 mg/kg chlorogenic acid intraperitoneally daily for 14 days, respectively. Blood-retinal barrier (BRB) breakdown was evaluated using FITC-dextran. Vascular endothelial growth factor (VEGF) distribution and expression level was evaluated with immunohistochemistry and Western blot analysis. Expression of tight junction proteins, occludin and claudin-5, and zonula occludens protein, ZO-1 was also evaluated with immunohistochemistry and Western blot analysis. BRB breakdown and increased vascular leakage was found in diabetic rats, with increased VEGF expression and down-regulation of occludin, claudin-5, and ZO-1. CGA treatment effectively preserved the expression of occludin, and decreased VEGF levels, leading to less BRB breakdown and less vascular leakage. CGA may have a preventive role in BRB breakdown in diabetic retinopathy by preserving tight junction protein levels and low VEGF levels.
Animals ; Blood-Retinal Barrier/*drug effects ; Chlorogenic Acid/metabolism/*pharmacology ; Claudin-5/metabolism ; Dextrans/chemistry ; Diabetes Mellitus, Experimental/complications/metabolism/*pathology ; Diabetic Retinopathy/etiology/prevention & control ; Down-Regulation ; Fluorescein-5-isothiocyanate/chemistry ; Male ; Occludin/metabolism ; Rats ; Rats, Sprague-Dawley ; Retina/*metabolism ; Tight Junction Proteins/metabolism ; Vascular Endothelial Growth Factor A/metabolism ; Zonula Occludens-1 Protein/metabolism