Portulaca oleracea L. prevents lipopolysaccharide-induced passive avoidance learning and memory and TNF-α impairments in hippocampus of rat.

There is a growing body of evidence that neuroinflammation can impair memory. It has been indicated that Portulaca oleracea Linn. (POL), possess anti-inflammatory activity and might improve memory disruption caused by inflammation. In this study the effect of pre-treatment with the hydro-alcoholic extract of POL on memory retrieval investigated in lipopolysaccharide (LPS) treated rats. Male Wistar rats (200-220g) received either a control diet or a diet containing of POL (400mg/kg, p.o.) for 14days. Then, they received injections of either saline or LPS (1mg/kg, i.p.). In all the experimental groups, 4h following the last injection, passive avoidance learning (PAL) and memory test was performed. The retention test was done 24h after the training and then the animals were sacrificed. Hippocampal TNF-α levels measured using ELISA as one criteria of LPS-induced neuroinflammation. The results indicated that LPS significantly impaired PAL and memory and increased TNF-α levels in hippocampus tissue. Pre-treatment with POL improved memory in control rats and prevented memory and TNF-α deterioration in LPS treated rats. Taken together, the results of this study suggest that the hydro-alcoholic extract of POL may improve memory deficits in LPS treated rats, possibly via inhibition of TNF-α and anti-inflammatory activity.

Omega-3 fatty acids prevent LPS-induced passive avoidance learning and memory and CaMKII-α gene expression impairments in hippocampus of rat.

BACKGROUND: Neuroinflammation is considered to be a major factor in several neurodegenerative diseases. Recently, the polyunsaturated fatty acid omega-3 has been shown to have anti-inflammatory effects and might play an effective role in improving memory impairment due to inflammation. In order to test this, we stimulated neuroinflammation in an animal model and induced memory dysfunction as measured by reduced retention of passive avoidance learning (PAL) and altered expression of CaMKII-α, a gene known to be crucial for memory formation. We then investigated whether treatment with dietary omega-3 prevents inflammation-induced memory dysfunction in this model. METHODS: Male wistar rats (200-220 g) were fed either a control diet or a diet containing omega-3 (400mg/kg, po) for 1 month prior. Rats then received injection of either saline or LPS (500 µg/kg, ip) and were subjected to the PAL acquisition task. The retention test was performed 24h later, and animals were sacrificed immediately. Hippocampi were dissected and stored at -80°C. Finally, TNF-α levels and CaMKII-α gene expression were measured by ELISA and qRT-PCR, respectively. RESULTS: We found that LPS treatment significantly impaired PAL and memory, increased TNF-α levels and impaired CaMKII-α gene expression. In control and LPS-injected animals, pre-treatment with omega-3 improved performance on the PAL task and increased CAMKII-α gene expression. CONCLUSION: Taken together, these data suggest that dietary omega-3 may improve cognitive function and provide a potential therapy for memory impairment due to neuroinflammation.