Ischemic preconditioning reduces peripheral oxidative damage associated with brain ischemia in rats

Neuroprotective Effect of Platinum Nanoparticles Is Not Associated with Their Accumulation in the Brain of Rats

Platinum nanoparticles (nPts) have neuroprotective/antioxidant properties, but the mechanisms of their action in cerebrovascular disease remain unclear. We investigated the brain bioavailability of nPts and their effects on brain damage, cerebral blood flow (CBF), and development of brain and systemic oxidative stress (OS) in a model of cerebral ischemia (hemorrhage + temporary bilateral common carotid artery occlusion, tBCAO) in rats. The nPts (0.04 g/L, 3 ± 1 nm diameter) were administered to rats (N = 19) intraperitoneally at the start of blood reperfusion. Measurement of CBF via laser Doppler flowmetry revealed that the nPts caused a rapid attenuation of postischemic hypoperfusion. The nPts attenuated the apoptosis of hippocampal neurons, the decrease in reduced aminothiols level in plasma, and the glutathione redox status in the brain, which were induced by tBCAO. The content of Pt in the brain was extremely low (≤1 ng/g). Thus, nPts, despite the extremely low brain bioavailability, can attenuate the development of brain OS, CBF dysregulation, and neuronal apoptosis. This may indicate that the neuroprotective effects of nPts are due to indirect mechanisms rather than direct activity in the brain tissue. Research on such mechanisms may offer a promising trend in the treatment of acute disorders of CBF.

Disturbance of thiol/disulfide aminothiols homeostasis in patients with acute ischemic stroke stroke: Preliminary findings

OBJECTIVES

To determine the disruption of low-molecular-weight aminothiols (LMWTs: cysteine, cysteinylglycine, homocysteine, and glutathione) homeostasis in blood plasma during the acute and early subacute stages after ischemic stroke.

PATIENTS AND METHODS

We admitted 41 patients with primary large-artery atherosclerosis and cardioembolic stroke in the carotid arteries within the first 6-24 h from the moment of neurologic symptoms development. We included 31 patients with chronic cerebral ischemia in the control group. Total LMWT levels and their reduced forms were measured in blood plasma on the 1st, 3rd, 7th, and 15th days after stroke.

RESULTS

Our study demonstrated a decrease of cysteine and cysteinylglycine reduced forms and an increase of total glutathione and cysteine levels. There were no differences in LMWT levels among stroke subtypes (large-artery atherosclerosis and cardioembolic stroke). The decrease (or increase) in GSH and Hcy redox status on the 3^rd day after stroke was associated with severe neurological deficit. Total Hcy (1^st day), Cys (3^rd day) and CG(7^th day) levels were associated with the size of cerebral infarction area. Logistic regression analysis indicated that reduced homocysteine, total cysteinylglycine levels, and cysteine redox status at admission were predictive factors for ischemic stroke occurrence with a probability of 86.2% (p < 0.001).

CONCLUSIONS

LMWTs may indicate the severity of neurological deficit and the size of the cerebral infarct, and their complex determination can be of diagnostic importance both at an early stage of ischemic stroke development and during its monitoring.

Plasma low-molecular-weight thiol/disulphide homeostasis as an early indicator of global and focal cerebral ischaemia

OBJECTIVE

Recent studies have shown that cerebral ischaemia causes not only local, but also systemic oxidative stress. This leads to oxidation of thiol-containing compounds, including low-molecular-weight thiols (cysteine, glutathione, homocysteine and others). Therefore, the aim of this work was to verify the hypothesis that the thiol/disulphide homeostasis of low-molecular-weight thiols is disturbed in the early stages of cerebral ischaemia.

METHODS

Two experimental rat models of ischaemia were used: a global model of vascular ischaemia (clamping the common carotid arteries + haemorrhage) and focal ischaemia (middle cerebral artery occlusion). The total levels of thiols and their reduced forms were measured before surgery and after 40 minutes of reperfusion (global) or 3 hours (focal) ischaemia.

RESULTS

The global ischaemia model caused a marked (2.5-4 times, P < 0.01) decrease in the plasma thiol/disulphide redox state, and focal ischaemia caused an even larger decrease (30-80 times, P < 0.001).

DISCUSSION

These results suggest that plasma low-molecular-weight thiols are actively involved in oxidation reactions at early stages of cerebral ischaemia; therefore, their reduced forms or redox state may serve as a sensitive indicator of acute cerebrovascular insufficiency.

Time course of peripheral oxidative stress as consequence of global ischaemic brain injury in rats

Free radicals play an important role in the pathogenesis of brain injury. This study evaluates the potential relationship between ischaemia/reperfusion (I/R)-induced brain injury, peripheral oxidative stress (lymphocyte DNA damage), plasma antioxidant potential and uric acid levels. We observed that 15 min of ischaemia were sufficient to significantly increase lymphocyte DNA damage that remained elevated at the end of early (3 h) reperfusion and at later (72 h) reperfusion time; this parameter was not significantly increased, when compared to preoperated levels. In parallel, antioxidant potential was elevated after 15 min of ischaemia, remained high at early (3 h) reperfusion and decreased again with longer (72 h) reperfusion. A close association between the plasma antioxidant status and the uric acid content has been confirmed by findings that changes in TRAP values positively correlate with uric acid concentration in rat plasma after ischaemic injury. Moreover, results of in vitro experiments with extra uric acid addition to control plasma have shown that uric acid contributes to a greater part of TRAP values. These results indicate a similar time course of brain I/R-associated oxidative stress and peripheral antioxidant defence status and/or oxidative stress in animal experiments.