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

Abstract

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.

Figure 1. Total neurological score (normal score = 0, maximal score = 12) during MCAo (60 min) and on days 1, 2 and 3 after treatment.

Treatment with DHA-Alb significantly improved neurological scores at 48 and 72 h. Values shown are means ± SEM. ^# P<0.05 versus saline group; *P<0.05 versus Alb (0.63 or 1.25 g/kg) groups (two-way repeated-measures ANOVA).

Figure 2. Representative ex vivo T2WI from all groups on day 3 after MCAo.

Panel A: T2WI were pseudocolored to identify regions of abnormality (green to red) compared to normal brain tissues (black to blue). T2 hyperintensities were observed in the cortex and striatum of saline- and Alb-treated rats, consistent with edema formation. In contrast, DHA-Alb- (1.25 g/kg) treated animals had smaller lesion size, with mostly subcortical involvement. Panel B: Total lesion volumes were computed from T2WI. Lesion volume was reduced in DHA-Alb (1.25 g/kg) and DHA groups compared to the saline group. Treatment with DHA-Alb (1.25 g/kg) significantly reduced total lesion volumes compared to the corresponding Alb-treated group. Values shown are means ± SEM. ^# P<0.05 versus saline group; *P<0.05 versus Alb (1.25 g/kg) group (two-way repeated-measures ANOVA).

Figure 3. Computer-generated MosaiX-processed images of Nissl stained paraffin-embedded brain sections from rats treated with saline, DHA, Alb (0.63 and 1.25 g/kg) and DHA-Alb (0.63 and 1.25 g/kg) on day 3 after stroke.

Saline- and both Alb-treated animals show large cortical and subcortical infarction. DHA-Alb- (0.63 g/kg) and DHA-treated rats showed moderate infarct involving cortical and subcortical regions. In contrast, rats treated with DHA-Alb (1.25 g/kg) showed less extensive damage, mostly in the subcortical area.

Figure 4. Histopathology on day 3 of survival.

Cortical, subcortical and total integrated infarct areas and volumes in rats after permanent MCAo. Treatment with both doses of DHA-Alb reduced cortical, subcortical and total infarct volumes when treatment was administered at 3 h after onset of MCAo. Data are mean ± SEM. ^# P<0.05 versus saline group; *P<0.05 versus Alb (0.63 or 1.25 g/kg) groups (repeated-measures ANOVA followed by Bonferroni tests).