Carbonyl histochemistry in rat reperfusion nerve injury

Abstract

Free radical mediated, site-specific lipid and protein oxidation has been implicated in the pathophysiology of an ischaemic/reperfusion injury. The aim of the present study was to determine whether carbonyl formation could be detected histochemically in reperfused rat sciatic nerves. We also examined the effects of preischaemic α-tocopherol supplementation on carbonyl formation in reperfused nerves. Seven hours of near-complete ischaemia was induced in rat right hindlimb by occlusion of major arteries using microvascular clips. Histochemical detection of carbonyl compounds, applying naphthoic acid hydrazide (NAH) and Fast Blue B (FBB), was undertaken at thigh, knee and calf levels of sciatic, tibial and peroneal nerves. NAH–FBB reactivity was confined to vessels in reperfused nerves. Positively stained epi-, peri- and endoneurial vessels were invariably observed after 2 h of reperfusion at all levels examined. After 24 and 48 h and 7 days of reperfusion, NAH–FBB-positive vessels were more frequently found at knee and calf levels than at the thigh level. Following preischaemic α-tocopherol supplementation, no vessels were stained positively with NAH–FBB, except for some epineurial vessels at knee and calf levels after 2 h of reperfusion. Morphometry in endoneurial vessels at the knee level revealed that endothelial cell area in α-tocopherol-treated reperfused nerves was significantly less when compared with those in reperfused nerves without α-tocopherol. In conclusion, we have demonstrated histochemical evidence of carbonyl formation in vessels, but not with nerve fibres, in ischaemic/reperfused rat sciatic nerves. These abnormalities were prevented with preischaemic supplementation of α-tocopherol.