Individual and synergistic effects of walnut oil and blueberry treatments on reducing neuroinflammation in rat microglial cells in vitro

Authors: Fisher, Derek; CAHOON, DANIELLE - Tufts University; Shukitt-Hale, Barbara

Submitted to: Society for Neuroscience Abstracts and Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/20/2019
Publication Date: 10/20/2019
Citation: Fisher, D.R., Cahoon, D.S., Shukitt Hale, B. 2020. Individual and synergistic effects of walnut oil and blueberry treatments on reducing neuroinflammation in rat microglial cells in vitro [abstract]. Society for Neuroscience Abstracts and Proceedings. 2019 Society for Neuroscience Annual Meeting Program # 208.13.

Interpretive Summary:

Technical Abstract: With age, increased generation of free radicals and decreased endogenous defense enzymes result in oxidative stress and pro-inflammatory signals that ultimately disrupt or destroy cells. Age-related neurodegeneration and behavioral declines have been associated with increases in neuroinflammation and oxidative stress in the brain. Therefore, plant polyphenols high in antioxidant and anti-inflammatory activity, such as those in berries and nuts, may prevent or reduce the neurochemical and behavioral declines that occur in aging. Previous in vitro and animal studies from our laboratory have shown that blueberries and walnuts are able to attenuate markers of neuroinflammation as well as age-related behavioral deficits. While blueberries and walnuts each provide neuroprotective dietary components, they also may act synergistically to enhance the effects seen with individual supplementation due to their unique compounds. Therefore, relative to individual treatments, combined walnut oil/blueberry (WO/BB) treatments may: 1) have increased beneficial effects due to synergistic mechanisms; 2) have the same effects due to overlapping additive properties; or 3) have a reduced beneficial effect, as the individual doses are lower, or due to another unknown mechanism. This study investigated the in vitro protective effects of blueberry, walnut oil, and combined blueberry/walnut oil treatments on LPS-induced neuroinflammation in rat microglial cells at various concentrations and treatment durations. HAPI rat microglial cells were treated with freeze-dried blueberry extract, walnut oil, or WO/BB at 0.05, 0.1, 0.2, 0.5 and 1.0 mg/mL for 48 hours, 1 week, 2 weeks and 4 weeks. At the end of each treatment time point, cells were stressed with LPS at 100 ng/mL overnight and expression of nitric oxide, TNF-alpha, COX-2 and iNOS were measured as inflammatory indices. Results showed that blueberry and walnut oil treatments reduced LPS-induced neuroinflammation in a concentration- and time-dependent manner. However, treatment with blueberry had a stronger effect on reducing neuroinflammation than WO/BB, and both blueberry and WO/BB were more effective than walnut oil. This suggests that the blueberry in the combined treatment is primarily responsible for the beneficial effects of WO/BB, and blueberry and walnut oil do not act synergistically to reduce neuroinflammation.