Inhibition of Nad(p)h Oxidase Reduces Fibronectin Expression in Stroke‐prone Renovascular Hypertensive Rat Brain

Abstract

1. The aim of the present study was to test the hypothesis that in vivo chronic inhibition of NAD(P)H oxidase reduces cerebrovascular fibronectin expression in stroke-prone renovascular hypertensive rats (RHRSP). 2. The RHRSP model was induced by two clips and NAD(P)H oxidase was inhibited with apocynin. The mRNA and protein expression of NAD(P)H oxidase subunit p22(phox) in brains of RHRSP and Sprague-Dawley (control) rats was determined using real-time reverse transcription-polymerase chain reaction, western blot and immunohistochemistry. The expression of fibronectin protein was localized immunohistochemically in cerebral vessels and then quantified by western blot. 3. Cerebrovascular fibronectin levels in RHRSP (n = 6) were significantly higher than control (n = 5) levels 8 weeks after operation (1.29 +/- 0.04 vs 1.15 +/- 0.02, respectively; P = 0.007). The p22(phox) immunopositive reactivity was localized in the cerebral vasculature of control rats and RHRSP. Furthermore, chronic treatment of RHRSP with apocynin, a selective NAD(P)H oxidase inhibitor, in the drinking water for 4 weeks (1.5 mmol/L, 5 weeks after operation) resulted in a significant decrease in the expression of p22(phox) protein (0.85 +/- 0.01 vs 0.93 +/- 0.01 in non-treated RHRSP; n = 5; P = 0.002), with a concomitant reduction of fibronectin levels in the cerebral vasculature (1.31 +/- 0.03 vs 1.56 +/- 0.05 in non-treated RHRSP; n = 5; P = 0.002). No significant differences were detected in the expression of p22(phox) mRNA and protein between RHRSP (4 and 8 weeks after renal artery constriction) and the control group. 4. These findings suggest that the chronic inhibition of NAD(P)H oxidase in vivo by apocynin reduces cerebrovascular fibronectin levels, which may lessen hypertensive cerebrovascular fibrosis.

Protective effects of apocynin on cisplatin‐induced ototoxicity in an auditory cell line and in zebrafish

“…It was reported that apocynin reduced the overproduction of O 2 •− by the left ventricle and the rise in advanced oxidation protein products induced by angiotensin II (Rugale et al ., ). This result strongly suggests that apocynin can inhibit not only NADPH oxidase activity but also the expression of this enzyme (Pech et al ., ; Cui et al ., ) and that the inhibition of NADPH oxidase in vivo by apocynin prevents some dysfunctions in more than a few pathological entities (Chirino et al ., ).…”

“…It is well known that these results are very important for the assembly of the functional NADPH oxidase complex and apocynin has been used to investigate the role of this NADPH oxidase in several studies (Pech et al, 2006;Rugale et al, 2005;Cui et al, 2007, Chirino et al, 2008. It was reported that apocynin reduced the overproduction of O 2 • À by the left ventricle and the rise in advanced oxidation protein products induced by angiotensin II (Rugale et al, 2005).…”

“…Many agents have been studied to evaluate their protective effects against cisplatin-induced ototoxicity, including L-methionine, L-N-acetylcysteine, fosfomycin, sodium salicylate, D-methionine, diethyldithiocarbamate, lipoic acid, glutathione ester and epicatechin (Schweitzer et al, 1986;Rybak et al, 1995Rybak et al, , 1999Campbell et al, 1996Campbell et al, , 2003aFeghali et al, 2001;Li et al, 2001Li et al, , 2002Kim et al, 2008). Apocynin, a specific NADPH oxidase inhibitor (Muijsers et al, 2000;Erdos et al, 2006;Chan et al, 2007;Gracia-Sancho et al, 2007;Chirino et al, 2008), has been shown to protect tissue damage in several experimental models (Rugale et al, 2005;Pech et al, 2006;Cui et al, 2007;Chirino et al, 2008). Zebrafish have hair cells on the surface of their body in a sensory system referred to as the lateral line.…”

Scutellarin Attenuates Hypertension-Induced Expression of Brain Toll-Like Receptor 4/Nuclear Factor Kappa B

“…Renal arteries in sham-operated rats also underwent surgery but without placement of clips. Systolic blood pressure (SBP) was measured by an indirect tail-cuff sphygmomanometer (MRB-IIIA, Shanghai Institute of Hypertension, Shanghai, China) in conscious rats heated (heat lamp at 37°C, for 5 min) before and after renal artery constriction (at weekly intervals) for 10 weeks [23]. …”

Targeting NOX enzymes in the central nervous system: therapeutic opportunities

“…Even if beneficial, this treatment can be performed in patients only 3-4 h after the occurrence of stroke, because of the associated severe risk of inducing a hemorrhage [99]. Since it is difficult to rescue the infarcted area, possible therapies are designed to reduce further development of tissue damage and cognitive Pharmacological targeting of NOX in the CNS 2393 improved neurological outcome, attenuated superoxide production in alcohol-fed rats [171] Ischemic brain injury associated with hypertension Two renal arteries were constricted bilaterally with two ring-shaped silver clips Stroke-prone renovascular hypertensive rats 1.5 mmol/L Per os in the drinking water for 28 days beginning on the 5th week after the operation Decrease in the expression of p22 phox protein and fibronectin levels in the cerebral vasculature [32] Ischemic brain injury associated with excess salt consumption 8% sodium diet from 11 weeks of age during 1, 2, or 4 weeks Stroke-prone spontaneously hypertensive rats 0.6 mmol/kg per day Per os in the drinking water for 4 weeks Reduced oxidative stress, cell death and stroke incidence [166] Pharmacological targeting of NOX in the CNS 2395 Amelioration of spatial learning deficits, decreased oxidative stress and apoptosis [60] impairment associated with the ischemic insult. Another approach is to prevent the occurrence of stroke in subjects at risk [134].…”