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.

Superior Neuroprotective Efficacy of LAU-0901, a Novel Platelet-Activating Factor Antagonist, in Experimental Stroke.

Platelet-activating factor (PAF) accumulates during cerebral ischemia, and inhibition of this process plays a critical role in neuronal survival. Recently, we demonstrated that LAU-0901, a novel PAF receptor antagonist, is neuroprotective in experimental stroke. We used magnetic resonance imaging in conjunction with behavior and immunohistopathology to expand our understanding of this novel therapeutic approach. Sprague-Dawley rats received 2 h middle cerebral artery occlusion (MCAo) and were treated with LAU-0901 (60 mg/kg) or vehicle 2 h from MCAo onset. Behavioral function, T2-weighted imaging (T2WI), and apparent diffusion coefficients were performed on days 1, 3, and 7 after MCAo. Infarct volume and number of GFAP, ED-1, and NeuN-positive cells were conducted on day 7. Behavioral deficit was significantly improved by LAU-0901 treatment compared to vehicle on days 1, 3, and 7. Total lesion volumes computed from T2WI were significantly reduced by LAU-0901 on days 1, 3, and 7 (by 83%, 90%, and 96%, respectively), which was consistent with decreased edema formation. Histopathology revealed that LAU-0901 treatment resulted in significant reduction of cortical and subcortical infarct volumes, attenuated microglial infiltration, and promoted astrocytic and neuronal survival. These findings suggest LAU-0901 is a promising neuroprotectant and provide the basis for future therapeutics in patients suffering ischemic stroke.

Behavioral sensitization and cross-sensitization between methylphenidate amphetamine, and 3,4-methylenedioxymethamphetamine (MDMA) in female SD rats.

The psychostimulants amphetamine and methylphenidate (MPD/Ritalin) are the drugs most often used to treat attention deficit hyperactivity disorder (ADHD). In addition, students of all ages take these drugs to improve academic performance but also abuse them for pleasurable enhancement. In addition, other psychostimulants such as 3,4-methylenedioxymethamphetamine (MDMA/ecstasy) are used/abused for similar objectives. One of the experimental markers for the potential of a drug to produce dependence is its ability to induce behavioral sensitization and cross sensitization with other drugs of abuse. The objective of this study is to use identical experimental protocols and behavioral assays to compare in female rats the effects of amphetamine, MPD and MDMA on locomotor activity and to determine if they induce behavioral sensitization and/or cross sensitization with each other. The main findings of this study are as follows: (1) acute amphetamine, MPD and MDMA all elicited increases in locomotor activity; (2) chronic administration of an intermediate dose of amphetamine or MPD elicited behavioral sensitization; (3) chronic administration of MDMA elicited behavioral sensitization in some animals and behavioral tolerance in others; (4) cross sensitization between MPD and amphetamine was observed; and (5) MDMA did not show either cross sensitization or cross tolerance with amphetamine. In conclusion, these results suggest that MDMA acts by different mechanisms compared to MPD and amphetamine.

Docosahexaenoic Acid therapy of experimental ischemic stroke.

We examined the neuroprotective efficacy of docosahexaenoic acid (DHA), an omega-3 essential fatty acid family member, in acute ischemic stroke; studied the therapeutic window; and investigated whether DHA administration after an ischemic stroke is able to salvage the penumbra. In each series described below, SD rats underwent 2 h of middle cerebral artery occlusion (MCAo). In series 1, DHA or saline was administered i.v. at 3, 4, 5, or 6 h after stroke. In series 2, MRI was conducted on days 1, 3 and 7. In series 3, DHA or saline was administered at 3 h, and lipidomic analysis was conducted on day 3. Treatment with DHA significantly improved behavior and reduced total infarct volume by a mean of 40% when administered at 3 h, by 66% at 4 h, and by 59% at 5 h. Total lesion volumes computed from T2-weighted images were reduced in the DHA group at all time points. Lipidomic analysis showed that DHA treatment potentiates neuroprotectin D1 (NPD1) synthesis in the penumbra 3 days after MCAo. DHA administration provides neurobehavioral recovery, reduces brain infarction and edema, and activates NPD1 synthesis in the penumbra when administered up to 5 h after focal cerebral ischemia in rats.

Robust docosahexaenoic acid-mediated neuroprotection in a rat model of transient, focal cerebral ischemia.

BACKGROUND AND PURPOSE: Docosahexaenoic acid (DHA; 22:6n-3), an omega-3 essential fatty acid family member, is the precursor of neuroprotectin D1, which downregulates apoptosis and, in turn, promotes cell survival. This study was conducted to assess whether DHA would show neuroprotective efficacy when systemically administered in different doses after middle cerebral artery occlusion (MCAo) in rats. METHODS: Sprague-Dawley rats were anesthetized with isoflurane and subjected to 2 hour of MCAo. Animals were treated with either DHA (low doses=3.5 or 7 mg/kg; medium doses=16 or 35 mg/kg; and high dose=70 mg/kg) or an equivalent volume of saline intravenously 3 hours after MCAo onset. Neurologic status was evaluated during occlusion (60 minutes) and on days 1, 2, 3, and 7 after MCAo. Seven days after MCAo, brains were perfusion-fixed, and infarct areas and volumes were determined. RESULTS: Only the low and medium doses of DHA significantly improved the neurologic score compared with vehicle-treated rats at 24 hours, 48 hours, 72 hours, and 7 days. DHA markedly reduced total corrected infarct volume in all treated groups compared with vehicle-treated rats (3.5 mg/kg, 26+/-9 mm(3); 7 mg/kg, 46+/-12 mm(3); 16 mg/kg, 37+/-5 mm(3); and 35 mg/kg, 34+/-15 mm(3) vs vehicle, 94+/-12 mm(3)). Cortical and striatal infarct volumes were also significantly reduced by treatment with DHA. No neuroprotective effects were observed with 70 mg/kg DHA. CONCLUSIONS: We conclude that DHA experimental therapy at low and medium doses improves neurologic and histologic outcomes after focal cerebral ischemia and might provide benefits in patients after ischemic stroke.