Acute treatment with docosahexaenoic acid complexed to albumin reduces injury after a permanent focal cerebral ischemia in rats

Docosahexaenoic acid complexed to albumin (DHA-Alb) is highly neuroprotective after temporary middle cerebral artery occlusion (MCAo), but whether a similar effect occurs in permanent MCAo is unknown. Male Sprague-Dawley rats (270-330 g) underwent permanent MCAo. Neurological function was evaluated on days 1, 2 and 3 after MCAo. We studied six groups: DHA (5 mg/kg), Alb (0.63 or 1.25 g/kg), DHA-Alb (5 mg/kg+0.63 g/kg or 5 mg/kg+1.25 g/kg) or saline. Treatment was administered i.v. at 3 h after onset of stroke (n = 7-10 per group). Ex vivo imaging of brains and histopathology were conducted on day 3. Saline- and Alb-treated rats developed severe neurological deficits but were not significantly different from one another. In contrast, rats treated with low and moderate doses of DHA-Alb showed improved neurological score compared to corresponding Alb groups on days 2 and 3. Total, cortical and subcortical lesion volumes computed from T2 weighted images were reduced following a moderate dose of DHA-Alb (1.25 g/kg) by 25%, 22%, 34%, respectively, compared to the Alb group. The total corrected, cortical and subcortical infarct volumes were reduced by low (by 36-40%) and moderate doses (by 34-42%) of DHA-Alb treatment compared to the Alb groups. In conclusion, DHA-Alb therapy is highly neuroprotective in permanent MCAo in rats. This treatment can provide the basis for future therapeutics for patients suffering from ischemic stroke.

Docosahexaenoic acid complexed to albumin provides neuroprotection after experimental stroke in aged rats

Recently we have shown that docosahexaenoic acid complexed to albumin (DHA-Alb) is neuroprotective after experimental stroke in young rats. The purpose of this study was to determine whether treatment with DHA-Alb would be protective in aged rats after focal cerebral ischemia. Isoflurane/nitrous oxide-anesthetized normothermic (brain temperature 36-36.5°C) Sprague-Dawley aged rats (18-months old) received 2h middle cerebral artery occlusion (MCAo) by poly-l-lysine-coated intraluminal suture. The neurological status was evaluated during occlusion (60min) and on days 1, 2, 3 and 7 after MCAo; a grading scale of 0-12 was employed. DHA (5mg/kg), Alb (0.63g/kg), DHA-Alb (5mg/kg+0.63g/kg) or saline was administered i.v. 3h after onset of stroke (n=8-10 per group). Ex vivo T2-weighted imaging (T2WI) of the brains was conducted on an 11.7T MRI on day 7 and 3D reconstructions were generated. Infarct volumes and number of GFAP (reactive astrocytes), ED-1 (activated microglia/microphages), NeuN (neurons)-positive cells and SMI-71 (positive vessels) were counted in the cortex and striatum at the level of the central lesion. Physiological variables were entirely comparable between groups. Animals treated with DHA-Alb showed significantly improved neurological scores compared to vehicle rats; 33% improvement on day 1; 39% on day 2; 41% on day 3; and 45% on day 7. Total and cortical lesion volumes computed from T2WI were significantly reduced by DHA-Alb treatment (62 and 69%, respectively). In addition, treatment with DHA-Alb reduced cortical and total brain infarction while promoting cell survival. We conclude that DHA-Alb therapy is highly neuroprotective in aged rats following focal cerebral ischemia and has potential for the effective treatment of ischemic stroke in aged individuals.

Abstract WP274: Novel Platelet-Activating Factor Receptor Antagonists are Highly Neuroprotective in Focal Cerebral Ischemia

INTRODUCTION: Platelet-activating factor (PAF) is a bioactive phospholipid that regulates synaptic activity and when overproduced is a potent mediator of leukocyte functions, including platelet aggregation and inflammation. PAF concentration increases during ischemia-reperfusion and is a mediator of neurotoxicity. The inhibition of this process plays a critical role in neuronal survival. We synthesized various analogues and identified them as PAF receptor antagonists, which were then selected for in vivo experiments to evaluate anti-ischemic activity.

METHODS: Physiologically controlled Sprague-Dawley rats received 2 h MCAo by poly-L-lysine-coated intraluminal suture. LAU compounds (LAU-0901, LAU-09015, LAU-09018, LAU-09019, LAU-09020 or LAU-09023; 30 mg/kg) or vehicle (45% cyclodextran) was administered IP at 2 h from onset of MCAo. Neurological status was evaluated during occlusion (at 60 min) and on day 1, 2, 3 and 7. Histopathology was carried out on day 7.

RESULTS: Physiological variables were stable and showed no significant differences between groups. All LAU compounds significantly reduced the neurobehavioral deficit compared to the vehicle group, beginning from day 1 and persisting through the 7 day survival period. Histologically, the vehicle group showed large hemispheric infarcts with pan-necrosis. By contrast, LAU-treated rats showed preserved hemispheric structure and small subcortical infarcts. Treatment with LAU (LAU-0901, LAU-09015, LAU-09018, LAU-09019, or LAU-09023) significantly reduced total infarct volume compared to the vehicle group by 68%, 52%, 40%, 51% and 54%, respectively.

CONCLUSION: Our results clearly indicate that novel LAU PAF receptor antagonists are highly neuroprotective on behavior and reduction of brain infarction in experimental stroke. These compounds may provide the basis for future therapeutics in patients suffering ischemic stroke.

This study was supported by NIH, NINDS grant R01 NS046741 (NGB).

Docosahexaenoic acid signaling modulates cell survival in experimental ischemic stroke penumbra and initiates long-term repair in young and aged rats

Background

Docosahexaenoic acid, a major omega-3 essential fatty acid family member, improves behavioral deficit and reduces infarct volume and edema after experimental focal cerebral ischemia. We hypothesize that DHA elicits neuroprotection by inducing AKT/p70S6K phosphorylation, which in turn leads to cell survival and protects against ischemic stroke in young and aged rats.

Methods and Results

Rats underwent 2 h of middle cerebral artery occlusion (MCAo). DHA, neuroprotectin D1 (NPD1) or vehicle (saline) was administered 3 h after onset of stroke. Neurological function was evaluated on days 1, 2, 3, and 7. DHA treatment improved functional recovery and reduced cortical, subcortical and total infarct volumes 7 days after stroke. DHA also reduced microglia infiltration and increased the number of astrocytes and neurons when compared to vehicle on days 1 and 7. Increases in p473 AKT and p308 AKT phosphorylation/activation were observed in animals treated with DHA 4 h after MCAo. Activation of other members of the AKT signaling pathway were also observed in DHA treated animals including increases in pS6 at 4 h and pGSK at 24 h. DHA or NPD1 remarkably reduced total and cortical infarct in aged rats. Moreover, we show that in young and aged rats DHA treatment after MCAo potentiates NPD1 biosynthesis. The phosphorylation of p308 AKT or pGSK was not different between groups in aged rats. However, pS6 expression was increased with DHA or NPD1 treatment when compared to vehicle.

Conclusions

We suggest that DHA induces cell survival, modulates the neuroinflammatory response and triggers long term restoration of synaptic circuits. Both DHA and NPD1 elicited remarkable protection in aged animals. Accordingly, activation of DHA signaling might provide benefits in the management of ischemic stroke both acutely as well as long term to limit ensuing disabilities.

Docosahexaenoic acid complexed to human albumin in experimental stroke: neuroprotective efficacy with a wide therapeutic window

BACKGROUND

Docosahexaenoic acid (DHA) complexed to human serum albumin (Alb) is neuroprotective after experimental stroke. Here we tested using lower concentrations of albumin as part of the complex to achieve neuroprotection. We found that lower Alb concentrations extend the therapeutic window of protection beyond 5 h after stroke onset.

METHODS

Sprague-Dawley rats were received 2 h middle cerebral artery occlusion (MCAo). The behavior was evaluated on day 1, 2, 3 and 7 after MCAo. In the dose-response study, animals were given either DHA (5mg/kg), Alb (0.63g/kg), DHA-Alb (5mg/kg + 0.32, 0.63 or 1.25 g/kg) or saline, i.v. 3 h after onset of stroke (n=6-8 per group). In the therapeutic window study, DHA-Alb (5mg/kg + 1.25g/kg) was administered i.v. at either 3, 4, 5, 6 or 7 h after onset of stroke (n=7-9 per group). Alb (1.25g/kg) was given at 3 h or 5 h and saline at 3h after onset of reperfusion. Seven days after MCAo, infarct volumes and number of GFAP, ED-1, NeuN, SMI-71 positive cells and vessels were counted.

RESULTS

Moderate DHA-Alb doses (0.63 and 1.25 g/kg) improved neurological scores compared to albumin-treated rats on days 1, 2, 3 and 7. All DHA-Alb doses (0.32, 0.63 and 1.25 g/kg) markedly reduced cortical (by 65-70%), striatal (by 52-63%) and total infarct volumes (by 60-64%) compared to native Alb group. In the therapeutic window study DHA-Alb led to improved neurological score and significant reductions of infarct volumes (especially in the cortical or penumbral region), even when treatment was initiated as late as 7 hours after onset of MCAo.

CONCLUSIONS

The DHA-Alb complex affords high-grade neurobehavioral neuroprotection in focal cerebral ischemia, equaling or exceeding that afforded by native Alb or DHA, at considerably moderate doses. It has a broad therapeutic window extending to 7 h after stroke onset. Taken together, these finding support the potential clinical feasibility of administering DHA-Alb therapy to patients with acute ischemic stroke.

Novel aspirin-triggered neuroprotectin D1 attenuates cerebral ischemic injury after experimental stroke

Acute ischemic stroke triggers complex neurovascular, neuroinflammatory and synaptic alterations. Aspirin and docosahexaenoic acid (DHA), an omega-3 essential fatty acid family member, have beneficial effects on cerebrovascular diseases. DHA is the precursor of neuroprotectin D1 (NPD1), which downregulates apoptosis and, in turn, promotes cell survival. Here we have tested the effect of aspirin plus DHA administration and discovered the synthesis of aspirin-triggered NPD1 (AT-NPD1) in the brain. Then we performed the total chemical synthesis of this molecule and tested in the setting of 2h middle cerebral artery occlusion (MCAo) in Sprague-Dawley rats. Neurological status was evaluated at 24h, 48 h, 72 h, and 7 days. At 3h post-stroke onset, an intravenous administration of 333 μg/kg of AT-NPD1 sodium salt (AT-NPD1-SS) or methyl-ester (AT-NPD1-ME) or vehicle (saline) as treatment was given. On day 7, ex vivo magnetic resonance imaging (MRI) of the brains was conducted on 11.7 T MRI. T2WI, 3D volumes, and apparent diffusion coefficient (ADC) maps were generated. In addition, infarct volumes and number of GFAP (reactive astrocytes), ED-1 (activated microglia/macrophages) and SMI-71-positive vessels were counted in the cortex and striatum at the level of the central lesion. All animals showed similar values for rectal and cranial temperatures, arterial blood gases, and plasma glucose during and after MCAo. Treatment with both AT-NPD1-SS and AT-NPD1-ME significantly improved neurological scores compared to saline treatment at 24h, 48 h, 72 h and 7 days. Total lesion volumes computed from T2WI images were significantly reduced by both AT-NPD1-SS and AT-NPD1-ME treatment in the cortex (by 44% and 81%), striatum (by 61% and 77%) and total infarct (by 48% and 78%, respectively). Brain edema, computed from T2WI in the cortex (penumbra) and striatum (core), was elevated in the saline group. In contrast, both AT-NPD1 decreased water content in the striatum on day 7. 3D volumes, computed from T2WI, were dramatically reduced with both AT-NPD1 and the lesion was mostly localized in the subcortical areas. Treatment with both AT-NPD1-SS and AT-NPD1-ME significantly reduced cortical (by 76% and 96%), subcortical (by 61% and 70%) and total (69% and 84%, respectively) infarct volumes as defined by histopathology. In conclusion, a novel biosynthetic pathway that leads to the formation of AT-NPD1 mediator in the brain was discovered. In addition, administration of synthetic AT-NPD1, in either its sodium salt or as the methyl ester, was able to attenuate cerebral ischemic injury which leads to a novel approach for pharmaceutical intervention and clinical translation.

Abstract 3098: Docosahexaenoic Acid Protects The Brain After Experimental Stroke By Modulating Protein Phosphorylation In The Penumbra

Background and purpose: Docosahexaenoic acid (DHA), a member of the omega-3 essential fatty acid family, improves behavioral deficit and reduces infarct volume and brain edema after focal cerebral ischemia in rats. We hypothesize that DHA elicits neuroprotection by inducing protective cellular cascades, which in turn lead to cell survival. We used behavioral tests in conjunction with immunohistopathology and western blots to expand our understanding of the early mechanisms responsible for DHA-induced neuroprotection.

Methods: Physiologically-controlled male Sprague-Dawley rats (304-370g) received 2h middle cerebral artery occlusion (MCAo) by intraluminal suture. Animals were treated with DHA (5mg/kg, iv) or saline (5ml/kg) at 3h after the onset of stroke. Behavioral function was evaluated at 1h after occlusion onset and at 24h on a grading scale of 0-12 (0=normal and 12=maximal deficit). GFAP (reactive astrocytes), ED-1 (activated microglia/microphages), and NeuN (neurons) were analyzed in the ischemic core and the penumbra regions (A, B and C) at 4 and 24h. Western blot/immunohistochemical analysis of pAKT, pGSK, and pS6 (proteins of the AKT signaling pathway) was conducted in the core and penumbra at 4 and 24h.

Results: Physiological variables were stable and showed no significant differences between groups. Behavioral deficit was significantly improved by treatment with DHA compared to vehicle at 24h (7.3±0.5 vs. 10±0; p<0.001, respectively). DHA treatment significantly reduced the number of microglia cells in penumbra regions A and C (by 86% and 76%) and increased GFAP-positive cells in penumbra regions B and C (by 53% and 51%) at 24h after stroke. There were no significant differences in expression of cell markers between groups at 4h and in the ischemic core. DHA upregulated activation of AKT compared to vehicle at 4h (36% increase in p473 AKT and 79% increase in p308 AKT) and at 24h (114% increase in p473 AKT; 98% increase in p308 AKT). DHA also increased pS6 at 4h by 160% and pGSK at 24h by 61% as compared to vehicle-treated animals. DHA-treated animals had significantly higher p308 AKT cell counts in the penumbra at 4h (region A by182%, region B by 160% and region C by 103% increase).

Conclusions: DHA treatment confers behavioral improvement, reduces microglial infiltration, increases astrocytosis at 24h, activates pro-survival AKT cascades as early as 4h, and has potential for the treatment of ischemic stroke.

Abstract 115: Aspirin-triggered Neuroprotectin D1 Protects The Penumbra In Focal Cerebral Ischemia In Rats

Background and Purpose: Acute ischemic stroke triggers complex neurovascular, neuroinflammatory and synaptic alterations. Aspirin and the omega-3 essential fatty acid, docosahexaenoic acid (DHA), have beneficial effects on cerebrovascular diseases. Unlike most anti-inflammatory agents, aspirin jumpstarts resolution mainly due to acetylation of cyclooxygenase enzymes. Both neuroprotectin D1 (NPD1) and its precursor, DHA, participate in neuroprotection. Here we have tested the effect of aspirin plus DHA administration and discovered the synthesis of aspirin-triggered NPD1 (AT-NPD1) in the penumbra. Then we performed the total chemical synthesis of this molecule and, upon systemic administration 1h after 2h of middle cerebral artery occlusion (MCAo), uncovered remarkable protection.

Methods: Sprague-Dawley rats were anesthetized with isoflurane and received 2h MCAo. Neurological status was evaluated at 24h, 48h, 72h, and 7 days. Treatment with 333µg/kg of AT-NPD1 sodium salt (AT-NPD1-SS) or AT-NPD1 methyl-ester (AT-NPD1-ME) or vehicle (saline) (n=7-8 per group) was administered i.v. at 3h after stroke. On day 7, ex vivo magnetic resonance imaging (MRI) of the brains was conducted on 11.7T MRI. T2WI, 3D volumes, and apparent diffusion coefficient (ADC) maps were generated. In addition, infarct volumes and number of GFAP (reactive astrocytes), ED-1 (activated microglia/microphages) and NeuN (neurons)-positive cells were counted in the cortex and striatum at the level of the central lesion.

Results: All animals showed similar values for rectal and cranial temperatures, arterial blood gases, and plasma glucose during and after MCAo. Treatment with both AT-NPD1-SS and AT-NPD1-ME significantly improved neurological scores compared to saline treatment at 24h, 48h, 72h and 7 days. Total lesion volumes computed from T2WI images were significantly reduced by both AT-NPD1-SS and AT-NPD1-ME treatment in the cortex (by 44% and 81%, respectively), striatum (by 61% and 77%) and total infarct (by 48% and 78%, respectively). Brain edema, computed from T2WI in the cortex (penumbra) and striatum (core), was elevated in the saline group. In contrast, both AT-NPD1-SS and AT-NPD1-ME decreased water content in the striatum on day 7. 3D volumes, computed from T2WI, were dramatically reduced with AT-NPD1-SS and AT-NPD1-ME, and the lesion was mostly localized in the subcortical areas. Treatment with both AT-NPD1-SS and AT-NPD1-ME significantly reduced cortical (by 76% and 96%), subcortical (by 61% and 70%) and total (69% and 84%) infarct volumes as defined by histopathology.

Conclusions: Ex vivo MRI, histopathology, and behavioral testing shows neuroprotective efficacy of novel AT-NPD1 therapy in focal cerebral ischemia and uncover a novel approach for pharmaceutical intervention and clinical translation.

Abstract 2964: A Novel Therapeutic Strategy For Experimental Stroke Using Docosahexaenoic Acid Complexed To Human Albumin

Background and Purpose: Recently we have shown that docosahexaenoic acid (DHA; 22:6, n-3) and human albumin (Alb) is neuroprotective after experimental stroke. However, administration of high-dose Alb by expanding intravascular volume may lead to pulmonary edema and congestive heart failure. We suspected that if Alb were complexed with DHA, it might be possible to achieve neuroprotection at lower Alb doses.

Methods: Male Sprague-Dawley rats were anesthetized with isoflurane/nitrous oxide and mechanically ventilated; rectal and cranial temperatures were regulated at 36-37.5 ° C. Rats received 2 h MCAo by retrograde insertion of an intraluminal suture. Animals received either DHA (5mg/kg), Alb (0.63g/kg), DHA-Alb (0.32, 0.63, 1.25g/kg) or an equivalent volume of vehicle (saline), which was administered at 3 h after onset of stroke into the femoral vein over 3 min using an infusion pump (n=8-10 per group). The neurological status was evaluated during occlusion (60 min), and on days 1, 2, 3 and 7 after MCAo; a grading scale of 0-12 was employed. Seven days after MCAo, brains were perfusion-fixed, and infarct areas and volumes were determined. Number of GFAP (reactive astrocytes), ED-1 (activated microglia/microphages) and NeuN (neurons)-positive cells were counted in the cortex and striatum at the level of the central lesion.

Results: The physiological variables were entirely comparable among all groups. Animals treated with moderate doses of DHA-Alb (0.63 and 1.25g/kg) significantly improved the neurological score compared to Alb-treated rats by 21 and 26% on day 1; by 28 and 29% on day 2; by 36 and 40% on day 3; and by 42 and 35% on day 7 (respectively). The lowest dose of DHA-Alb (0.32g/kg) was not significantly different from the Alb-treated group. In addition, DHA treatment improved behavioral score compared to the Alb-treated rats, but only on day 2 (by 19%) and day 3 (by 26%). All doses of DHA-Alb (0.32, 0.63 and 1.25g/kg) significantly reduced total (cortical and subcortical) corrected infarct volume in all treated groups compared to Alb-treated rats (by 64, 60 and 61%, respectively). Cortical and striatal infarct volumes were also significantly reduced by all doses of DHA-Alb. DHA treatment alone significantly reduced only striatal infarct volume compared to the Alb-treated group (22±4 vs. 52±9, respectively).

Conclusions: The DHA-Alb complex affords high-grade neurobehavioral neuroprotection in focal cerebral ischemia, equaling or exceeding that afforded by native Alb, at considerably moderate doses. It might provide the basis for future therapeutics in patients suffering ischemic stroke.