Blood-brain Barrier Integrity In Rats Research Articles

N-acetylcysteine Amide Ameliorates Blast-Induced Changes in Blood-Brain Barrier Integrity in Rats.

Traumatic brain injury resulting from exposure to blast overpressure (BOP) is associated with neuropathology including impairment of the blood-brain barrier (BBB). This study examined the effects of repeated exposure to primary BOP and post-blast treatment with an antioxidant, N-acetylcysteine amide (NACA) on the integrity of BBB. Anesthetized rats were exposed to three 110 kPa BOPs separated by 0.5 h. BBB integrity was examined in vivo via a cranial window allowing imaging of pial microcirculation by intravital microscopy. Tetramethylrhodamine isothiocyanate Dextran (TRITC-Dextran, mw = 40 kDa or 150 kDa) was injected intravenously 2.5 h after the first BOP exposure and the leakage of TRITC-Dextran from pial microvessels into the brain parenchyma was assessed. The animals were randomized into 6 groups (n = 5/group): four groups received 40 kDa TRITC-Dextran (BOP-40, sham-40, BOP-40 NACA, and sham-40 NACA), and two groups received 150 kDa TRITC-Dextran (BOP-150 and sham-150). NACA treated groups were administered NACA 2 h after the first BOP exposure. The rate of TRITC-Dextran leakage was significantly higher in BOP-40 than in sham-40 group. NACA treatment significantly reduced TRITC-Dextran leakage in BOP-40 NACA group and sham-40 NACA group presented the least amount of leakage. The rate of leakage in BOP-150 and sham-150 groups was comparable to sham-40 NACA and thus these groups were not assessed for the effects of NACA. Collectively, these data suggest that BBB integrity is compromised following BOP exposure and that NACA treatment at a single dose may significantly protect against blast-induced BBB breakdown.

Therapeutic Potential of Novel Twin Compounds Containing Tetramethylpyrazine and Carnitine Substructures in Experimental Ischemic Stroke.

Although studies have seen dramatic advances in the understanding of the pathogenesis of stroke such as oxidative stress, inflammation, excitotoxicity, calcium overload and apoptosis, the delivery of stroke therapies is still a great challenge. In this study, we designed and synthesized a series of novel twin compounds containing tetramethylpyrazine and carnitine substructures and explored their therapeutic potential and mechanism in stroke-related neuronal injury. We first screened the neuroprotective effects of candidate compounds and found that among the tested compounds, LR134 and LR143 exhibited significant neuroprotection as evidenced by reducing cerebral infarct and edema, improving neurological function as well as blood-brain barrier integrity in rats after cerebral ischemia/reperfusion injury. We further demonstrated that the neuroprotective effects of compounds LR134 and LR143 were associated with the reduced inflammatory responses and NADPH oxidase- (NOX2-) mediated oxidative stress and the protection of mitochondria accompanied by the improvement of energy supply. In summary, this study provides direct evidence showing that the novel twin compounds containing tetramethylpyrazine and carnitine substructures have neuroprotective effects with multiple therapeutic targets, suggesting that modulation of these chemical structures may be an innovative therapeutic strategy for treating patients with stroke.

Cordycepin attenuates traumatic brain injury-induced impairments of blood-brain barrier integrity in rats.

Loss of blood-brain barrier (BBB) integrity is a downstream event caused by traumatic brain injury (TBI). BBB integrity is affected by certain physiological conditions, including inflammation and oxidative stress. Cordycepin is a susbtance with anti-inflammatory and anti-oxidative effects. Therefore, it is necessary to investigate whether cordycepin affects TBI-induced impairments of BBB integrity. Using TBI rats as the in vivo model and applying multiple techniques, including stroke severity evaluation, Evans blue assessment, quantitative real-time PCR, Western blotting and ELISA, we investigated the dose-dependent protective effects of cordycepin on the TBI-induced impairments of BBB integrity. Cordycepin treatment attenuated the TBI-induced impairments in a dose-dependent manner, and played a role in protecting BBB integrity. Cordycepin was able to alleviate TBI-induced loss of tight junction proteins zonula occludens protein-1 (ZO-1) and occludin, which are important for BBB integrity. Moreover, cordycepin suppressed pro-inflammatory factors, including IL-1β, iNOS, MPO and MMP-9, and promoted anti-inflammation-associated factors arginase 1 and IL-10. Furthermore, cordycepin inhibited NADPH oxidase (NOX) expression and activity following TBI, probably through NOX1, but not NOX2 and NOX4. Cordycepin has protective effects against brain damages induced by TBI. The protection of cordycepin on BBB integrity was probably achieved through recovery of tight junction proteins, inhibition of local inflammation, and prevention of NOX activity.

Nafamostat mesilate protects against acute cerebral ischemia via blood–brain barrier protection

Serine proteases, such as thrombin, are contributors to the disruption of the blood–brain barrier (BBB) and exacerbate brain damage during ischemic stroke, for which the current clinical therapy remains unsatisfactory. However, the effect of nafamostat mesilate (NM), a synthetic serine protease inhibitor, on BBB disruption following cerebral ischemia is unknown. Here, we investigated the in vivo effect of NM on BBB integrity in rats subjected to transient middle cerebral artery occlusion (MCAO) and explored the possible mechanism in an in vitro BBB model comprising rat brain microvascular endothelial cells and astrocytes after oxygen and glucose deprivation (OGD) in the presence of thrombin. The results showed that NM treatment remarkably attenuated transient MCAO-induced brain infarcts, brain oedema and motor dysfunction in addition to BBB disruption, which might be related to changes in tight junction protein expression and localization. Meanwhile, NM preserved BBB integrity and alleviated the changes in tight junction protein expression and localization and cytoskeleton rearrangement in rat brain microvascular endothelial cells via thrombin inhibition. Our findings suggest that NM treatment can preserve BBB integrity through the inhibition of thrombin, which might be correlated with the regulation of PKCα/RhoA/MLC2 pathway components.

Platonin preserves blood–brain barrier integrity in septic rats

ObjectivesPlatonin possesses potent anti-inflammatory and antioxidative capacities. Because systemic inflammation and oxidative stress are crucial in mediating sepsis-induced blood–brain barrier (BBB) integrity loss, this study elucidated the effects of platonin on preserving BBB integrity in septic rats. MethodsA total of 72 adult male rats (200–250 g) were randomized to receive cecal ligation and puncture (CLP), CLP plus platonin, sham operation, or sham operation plus platonin (n = 18 in each group). Systemic inflammation and oxidation levels and BBB integrity in the surviving rats were determined after 24-hour monitoring. ResultsPlasma levels of interleukin-6 (IL-6) and malondialdehyde (MDA)—markers of systemic inflammation and oxidation—and the grading of Evans blue staining of the brains, BBB permeability to Evans blue dye, and brain edema levels—markers of BBB integrity—in rats that received CLP were significantly higher than rats that received sham operation (all p < 0.001). By contrast, the plasma levels of IL-6 (p < 0.001) and MDA (p < 0.001), and the grading of Evans blue staining (p = 0.015), BBB permeability to Evans blue dye (p = 0.043), and brain edema levels (p = 0.034) in rats that received CLP plus platonin were significantly lower than rats that received CLP. Experimental data further revealed that the concentration of tight junction protein claudin-5, a major structural component of BBB, in rats that received CLP was significantly lower than rats that received CLP plus platonin (p = 0.023). ConclusionPlatonin could attenuate sepsis-induced BBB integrity loss in rats.

3-[2-[4-(3-chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole dihydrochloride 3.5 hydrate (DY-9760e), a novel calmodulin antagonist, reduces brain edema through the inhibition of enhanced blood-brain barrier permeability after transient focal ischemia.

An alteration of the blood-brain barrier (BBB) permeability contributes to the development of brain edema after stroke. In this study, we evaluated the effects of 3-[2-[4-(3-chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole dihydrochloride 3.5 hydrate (DY-9760e), a novel calmodulin antagonist, on brain edema formation and BBB integrity in rats subjected to transient focal ischemia. DY-9760e (1 mg/kg/h) was intravenously infused for 6 h, starting immediately after reperfusion of a 1-h middle cerebral artery occlusion. Treatment with DY-9760e significantly suppressed the increase in water content and the extravasation of Evans blue dye after transient focal ischemia. Analysis of a magnetic resonance imaging method revealed that DY-9760e significantly prevented the development of brain edema in the cortical region of the ipsilateral hemisphere. Trifluoperazine, a calmodulin antagonist that is structurally different from DY-9760e, also attenuated brain edema elicited by transient focal ischemia. Furthermore, DY-9760e and trifluoperazine reduced tumor necrosis factor-alpha-induced hyperpermeability of inulin through a cultured brain microvascular endothelial cell monolayer, suggesting an involvement of calmodulin in the regulation of brain microvascular barrier function. The present results demonstrate that DY-9760e ameliorates brain edema formation and suggest that this effect may be mediated in part by the inhibition of enhanced BBB permeability after ischemic insults. Thus, DY-9760e is expected to be a therapeutic drug for treatment of acute stroke patients.