Dietary cis-9, trans-11-conjugated linoleic acid reduces amyloid ß-protein accumulation and upregulates anti-inflammatory cytokines in an Alzheimer's disease mouse model.

Conjugated linoleic acid (CLA) is an isomer of linoleic acid (LA). The predominant dietary CLA is cis-9, trans-11-CLA (c-9, t-11-CLA), which constitutes up to ~ 90% of total CLA and is thought to be responsible for the positive health benefits associated with CLA. However, the effects of c-9, t-11-CLA on Alzheimer's disease (AD) remain to be elucidated. In this study, we investigated the effect of dietary intake of c-9, t-11-CLA on the pathogenesis of an AD mouse model. We found that c-9, t-11-CLA diet-fed AD model mice significantly exhibited (1) a decrease in amyloid-ß protein (Aß) levels in the hippocampus, (2) an increase in the number of microglia, and (3) an increase in the number of astrocytes expressing the anti-inflammatory cytokines, interleukin-10 and 19 (IL-10, IL-19), with no change in the total number of astrocytes. In addition, liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatographic analysis revealed that the levels of lysophosphatidylcholine (LPC) containing c-9, t-11-CLA (CLA-LPC) and free c-9, t-11-CLA were significantly increased in the brain of c-9, t-11-CLA diet-fed mice. Thus, dietary c-9, t-11-CLA entered the brain and appeared to exhibit beneficial effects on AD, including a decrease in Aß levels and suppression of inflammation.

Interaction between Angiotensin Receptor and ß-Adrenergic Receptor Regulates the Production of Amyloid ß-Protein.

Alzheimer's disease (AD) is characterized by the formation of extracellular amyloid plaques containing the amyloid ß-protein (Aß) within the parenchyma of the brain. Aß is considered to be the key pathogenic factor of AD. Recently, we showed that Angiotensin II type 1 receptor (AT1R), which regulates blood pressure, is involved in Aß production, and that telmisartan (Telm), which is an angiotensin II receptor blocker (ARB), increased Aß production via AT1R. However, the precise mechanism underlying how AT1R is involved in Aß production is unknown. Interestingly, AT1R, a G protein-coupled receptor, was strongly suggested to be involved in signal transduction by heterodimerization with ß2-adrenergic receptor (ß2-AR), which is also shown to be involved in Aß generation. Therefore, in this study, we aimed to clarify whether the interaction between AT1R and ß2-AR is involved in the regulation of Aß production. To address this, we analyzed whether the increase in Aß production by Telm treatment is affected by ß-AR antagonist using fibroblasts overexpressing amyloid precursor protein (APP). We found that the increase in Aß production by Telm treatment was decreased by the treatment of ß2-AR selective antagonist ICI-118551 more strongly than the treatment of ß1-AR selective antagonists. Furthermore, deficiency of AT1R abolished the effect of ß2-AR antagonist on the stimulation of Aß production caused by Telm. Taken together, the interaction between AT1R and ß2-AR is likely to be involved in Aß production.