Focal Ischemic Injury with Complex Middle Cerebral Artery in Stroke-Prone Spontaneously Hypertensive Rats with Loss-Of-Function in NADPH Oxidases.

Hiroshi Yao,Hasan Md Zahid,Mohammed Zubaerul Ferdaus,Tatsuo Nakahara,Hiroki Ohara,Toru Nabika,Kazunori Toyoda

doi:10.1371/journal.pone.0138551

Hiroshi Yao, Hasan Md Zahid + Show 5 more

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https://doi.org/10.1371/journal.pone.0138551

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Journal: PloS one	Publication Date: Sep 21, 2015
Citations: 4	License type: CC BY 4.0

Affiliation: Hizen Psychiatric Center, Shimane University

Abstract

By means of introgressing a loss-of-function mutation in the p22phox gene from the Matsumoto Eosinophilia Shinshu (MES) rat to stroke-prone spontaneously hypertensive rats (SHRSP), we constructed the SHRSP-based congenic strain lacking the P22PHOX expression (i.e., lacking NADPH oxidases [NOX] activities) (SHRSP.MES-Cyba mes/Izm; hereafter referred to as SP.MES). To examine the effects of Nox activities on the focal ischemic injury or stroke, we performed middle cerebral artery (MCA) occlusion in this new congenic strain; the distal MCA was occluded by 561-nm laser-driven photothrombosis. Resting mean arterial blood pressure was significantly lower in SP.MES when compared with the control PM0/SHRSP (150±11 mmHg vs. 166±11 mmHg). Cerebral blood flow decreased to 37±13% in SP.MES and 35±17% in PM0/SHRSP at 10 min after MCA occlusion (not significant). Infarct volume determined at 24 h after MCA occlusion in SP.MES was 89±39 mm3, which was not significantly different from 83±35 mm3 in PM0/SHRSP. The distal MCA pattern was more complex in SP.MES (median 3, IQR 3–5) than PM0/SHRSP (median 2, IQR 1–3) (p = 0.001). Because more complex distal MCA is known to produce larger infarction after distal MCA occlusion in SHR, we adjusted for the branching pattern in an ANCOVA. The adjusted mean of infarct volume was significantly smaller in SP.MES compared with that in PM0/SHRSP (67 [95% CI 46 to 87] mm3 vs. 100 [95% CI 82 to 118] mm3, p = 0.032). Elimination of the P22PHOX expression induced complex distal MCA, which would suggest the presence of ‘loss of complexity’ induced by enhanced oxidative stress in SHRSP; infarct size in SP.MES—when adjusted for distal MCA complexity—was significantly attenuated compared with that in PM0/SHRSP. Therefore, the present results suggest that Nox is harmful for ischemic brain tissue.

Highlights

The nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (Nox)—only enzymes in terms of its primary function of generating superoxide—are the predominant source of reactive oxygen species [1]
After middle cerebral artery (MCA) occlusion, blood pressure increased in both groups, but the intra-ischemic MABP levels were still lower in SP.Matsumoto Eosinophilia Shinshu (MES) than in PM0/SHRSP (Fig 3A, 2-way analysis of variance (ANOVA), p
cerebral blood flow (CBF) decreased to 37±13% in SP.MES and 35±17% in PM0/SHRSP at 10 min after MCA occlusion (Fig 3B, 2-way ANOVA, not significant)

Summary

Introduction

The nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (Nox)—only enzymes in terms of its primary function of generating superoxide—are the predominant source of reactive oxygen species [1]. The Nox family is known to be composed of 7 catalytic subunits termed Nox 1 to 5 and Duox 1 and 2. Their physiological function is extremely diverse including host defense and inflammation, cellular signaling, gene expression, cellular death, cellular senescence, cell growth, oxygen sensing, angiogenesis, and so forth [2]. Basal and stimulated generation of superoxide from NADPH oxidases is 1 to 2 orders of magnitude higher in intracranial cerebral arteries than in systemic arteries, and activation of Nox in cerebral arteries can cause vasodilation under normal conditions [4]. Nox-knockout mice generally showed protection against focal ischemia or experimental stroke (i.e., the evidence for detrimental effects of Nox on stroke outcome) [1,6]

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