title: Restoration of stressor-induced calcium dysregulation and autophagy inhibition by polyphenol-rich açaí (Euterpe spp.) fruit pulp extracts in rodent brain cells in vitro.
abstract: OBJECTIVE
  Oxidative damage to lipids, proteins, and nucleic acids in the brain often causes progressive neuronal degeneration and death that are the focal traits of chronic and acute pathologies, including those involving cognitive decline. The aim of this study was to investigate the specific effects of both Euterpe oleracea and Euterpe precatoria açaí fruit pulp on restoring stressor-induced calcium dysregulation, stunted growth of basal dendrites, and autophagy inhibition using embryonic hippocampal and HT22 hippocampal neurons.
  
  
  METHODS
  Water-soluble whole fruit pulp extracts from two açaí species were applied to rat primary neurons and HT22 hippocampal neurons with varied time and concentrations. Recovery of neurons from dopamine-induced Ca(2+) dysregulation was measured by live cell imaging using fluorescent microscopy. The effect of açaí fruit pulp extracts on neurons following chemically-induced autophagy inhibition was measured using both immunofluorescence and immunohistochemical techniques.
  
  
  RESULTS
  It has been postulated that at least part of the loss of cognitive function in aging may depend on a dysregulation in calcium ion (Ca(2+)) homeostasis and a loss of autophagy function in the brain, which affects numerous signaling pathways and alters protein homeostasis. In the present study, polyphenol-rich fruit pulp extracts from two species of açaí, Euterpe precatoria and Euterpe oleracea, when applied to rat hippocampal primary neuronal cells (E18), caused a significant (P < 0.05) recovery of depolarized brain cells from dopamine-induced Ca(2+) influx. Autophagy, a protein homeostasis mechanism in brain, when blocked by known inhibitors such as bafilomycin A1 or wortmannin, caused a significant reduction in the growth of primary basal dendrites in rodent primary hippocampal neurons and significant accumulation of polyubiquitinated proteins in mouse HT22 hippocampal neurons in culture. However, pretreatment with açaí extracts up to 1 mg/mL significantly increased the length of basal dendrites and attenuated the inhibitor-induced autophagy dysfunction. Açaí extracts activated the phosphorylation of mammalian target of rapamycin, increased the turnover of autophagosomes and MAP1 B LC3-II, and decreased accumulation of LC3-ubiquitin binding P62/SQSTM1.
  
  
  CONCLUSIONS
  Although the polyphenol profile of Euterpe precatoria showed substantially higher concentrations of major flavonoids han Euterpe oleracea, the relative effects were essentially similar for both species. The study adds to growing evidence that supports the putative health effects of açaí fruit species on brain cells.
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts, USA.
authors.forename: Shibu M
authors.initials: SM
authors.lastname: Poulose
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts, USA.
authors.forename: Derek R
authors.initials: DR
authors.lastname: Fisher
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts, USA.
authors.forename: Donna F
authors.initials: DF
authors.lastname: Bielinski
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts, USA.
authors.forename: Stacey M
authors.initials: SM
authors.lastname: Gomes
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, National Center for Natural Products Research, University of Mississippi, USA.
authors.forename: Agnes M
authors.initials: AM
authors.lastname: Rimando
authors.affiliation: Natural and Medicinal Products Research, AIBMR Life Sciences, Puyallup, Washington, USA.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Schauss
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts, USA. Electronic address: Barbara.Shukitthale@ars.usda.gov.
authors.forename: Barbara
authors.initials: B
authors.lastname: Shukitt-Hale
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology / Q000627:therapeutic use; D001343:Autophagy / Q000187:drug effects*; D001921:Brain / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D003072:Cognition Disorders / Q000188:drug therapy / Q000378:metabolism*; D003712:Dendrites / Q000187:drug effects; D004298:Dopamine; D065748:Euterpe / Q000737:chemistry*; D005419:Flavonoids / Q000032:analysis / Q000494:pharmacology / Q000627:therapeutic use; D005638:Fruit / Q000737:chemistry; D006706:Homeostasis; D051379:Mice; D018384:Oxidative Stress / Q000502:physiology*; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D059808:Polyphenols / Q000494:pharmacology* / Q000627:therapeutic use; D011506:Proteins / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013045:Species Specificity
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D010936:Plant Extracts; D059808:Polyphenols; D011506:Proteins; D002118:Calcium; D004298:Dopamine
keywords: Autophagy; Açaí; Brain health; Inflammation; Neurons; Oxidative stress; Polyphenols