title: The Antidepressant Effect of L-Tyrosine-Loaded Nanoparticles: Behavioral Aspects.
abstract: BACKGROUND
  Depression has been linked to disruption in the cerebral levels of specific neurotransmitters. L-tyrosine is a precursor of more than one of the neurotransmitters affected by depression. Even though setbacks of monoamines precursors include high doses and low efficiency, many studies have suggested using L-tyrosine as antidepressant.
  
  
  OBJECTIVE
  The purpose of this study was to explore the possible antidepressant effect of L-tyrosine loaded in a nanoparticle-designed formula, using behavioral tests in acute and chronic mild stress (CMS) models of depression in rats.
  
  
  METHODS
  Animals from both models received L-tyrosine-loaded nanoparticles (5 or 10 mg/kg), L-tyrosine solution (10 mg/kg), fluoxetine (10 mg/kg) or placebo daily for 21 days. Rats from the acute stress model of depression were subjected to open field and forced swim tests (FSTs). For the CMS model, sucrose preference test was carried out. Additionally, 3 profiles of the nanoparticles formula were tested in vitro. High dissolution rate and entrapment efficiency were obtained from the in vitro tests. Moreover, L-tyrosine-loaded nanoparticles 10 mg/kg and fluoxetine 10 mg/kg significantly decreased the immobility time in the FST, concomitant with restoration of the basal levels of locomotor activity, distance travelled and rearing counts. Also, an increase of the sucrose consumption was recorded in the sucrose preference test after treatment with L-tyrosine-loaded nanoparticles 10 mg/kg and fluoxetine 10 mg/kg.
  
  
  RESULTS
  The positive results after treatment with L-tyrosine-loaded nanoparticles, through behavioral tests, are probably attributed to restorating the basal levels of the cerebral noradrenaline.
  
  
  CONCLUSIONS
  The effects of L-tyrosine administration on the cerebral levels of tyrosine hydroxylase and corticotropin-releasing factor should be further investigated.
authors.affiliation: Faculty of Science, University of Alexandria - University of Bordeaux II, Aarhus C, Denmark.
authors.forename: Abdelrahman
authors.initials: A
authors.lastname: Alabsi
authors.affiliation: Faculty of Science, University of Alexandria - University of Bordeaux II, Aarhus C, Denmark.
authors.forename: Adel Charbel
authors.initials: AC
authors.lastname: Khoudary
authors.affiliation: Department of Pharmaceutics, Faculty of Pharmacy, University of Aleppo, Aleppo, Syrian Arab Republic.
authors.forename: Wassim
authors.initials: W
authors.lastname: Abdelwahed
keywords: Depression; Forced swim test; Loco-motor activity; Open field test; Sucrose preference test