Cinnamon counteracts the negative effects of a high fat/high fructose diet on behavior, brain insulin signaling and Alzheimer-associated changes

Authors: Anderson, Richard; QIN, BOLIN - Integrity Neutraceuticals; CANINI, FREDERIC - Joseph Fourier University; POULET, LAURENT - Joseph Fourier University; ROUSSEL, ANNE - Joseph Fourier University

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2013
Publication Date: 12/13/2013
Citation: Anderson, R.A., Qin, B., Canini, F., Poulet, L., Roussel, A.M. 2013. Cinnamon counteracts the negative effects of a high fat/high fructose diet on behavior, brain insulin signaling and Alzheimer-associated changes. PLoS One. 8(12):e83243.

Interpretive Summary: Close to two thirds of the adult population in the US has varying degrees of insulin resistance which may lead to memory impairment. Cinnamon improves whole body insulin resistance but its effects in the brain are not known. In this study, we demonstrated that feeding rats a diet high in fat and fructose led to not only insulin resistance but also impaired mental acuity that was prevented in animals eating the same diet with added cinnamon. The cinnamon fed rats were more active and curious in a Y maze test than rats fed the control and high fat/high fructose diet. The high fat/high fructose fed rats showed greater anxiety in an elevated plus maze test that was lessened by feeding cinnamon. The high fat/high fructose diet also led to a down regulation of the genes coding for the transport of glucose that was reversed by cinnamon in the hippocampus and cortex. The high fat/high fructose diet also induced increases in genes associated with Alzheimer’s disease that were also alleviated by cinnamon. In summary, the negative effects of a high fat/high fructose diet on behavior, brain insulin signaling and Alzheimer-associated changes were alleviated by cinnamon suggesting neuroprotective effects of cinnamon associated with improved insulin sensitivity.

Technical Abstract: Insulin resistance leads to memory impairment. Cinnamon (CN) improves whole body insulin resistance but its effects in the brain are not known. Changes in behavior, insulin signaling, and Alzheimer-associated gene expression in the brain were measured in male Wistar rats fed a high fat/high fructose (HF/HFr) diet to induce insulin resistance, with or without CN, for 12 weeks. There was a decrease in insulin sensitivity associated with the HF/HFr diet that was reversed by CN. The CN fed rats were more active and curious in a Y maze test than rats fed the control and HF/HFr diets. The HF/HFr diet fed rats showed greater anxiety in an elevated plus maze test that was lessened by feeding CN. The HF/HFr diet also led to a down regulation of the genes coding for GLU1 and GLUT3 that was reversed by CN in the hippocampus and cortex. There were increases in Ir, Irs1, and Irs2 genes in the hippocampus and cortex due to the HF/HFr diet that were not reversed by CN. Increased insulin sensitivity was also associated with increased glycogen synthase in both hippocampus and cortex in the control and HF/HFr diet animals fed CN. The HF/HFr diet induced increases in genes associated with Alzheimers including Pten, Tau, and amyloid precursor protein were also alleviated by CN. In summary, the negative effects of a HF/HFr diet on behavior, brain insulin signaling and Alzheimer-associated changes were alleviated by CN suggesting neuroprotective effects of CN associated with improved insulin sensitivity.