title: Neurobehavioural and neurotoxic effects of L-ascorbic acid and L-tryptophan in lead exposed rats.
abstract: BACKGROUND
  Lead is an environmental toxicant, occupational and environmental exposures remain a serious problem in developing and industrializing countries.
  
  
  OBJECTIVE
  This study is designed to investigate the effects of L-ascorbic acid and L-tryptophan on the neurotoxicity and neurobehavioural alterations in lead exposed male Sprague Dawley rats.
  
  
  METHODS
  Experimental animals were exposed to oral doses of lead (Pb), L-ascorbic acid, and L-tryptophan at 75 mg/kg body weight, 40 mg/kg body weight, and 20 mg/kg body weight respectively, while control animals received 0.90% saline solution. Oral administration spanned for four weeks after which changes in neuro-behaviour, organ weight, blood deposition of Pb, brain serotonin, tryptophan and neuronal redox status were determined. Changes in organ weight, blood lead levels, neuro-behavioural characteristics, brain serotonin and tryptophan contents, and brain redox status were determined.
  
  
  RESULTS
  The results indicated that Pb exposure increased blood lead, organ-weight index, and behavioural signs of anxiety and aggression. The sub-chronic exposure to Pb also decreased brain serotonin, while causing oxidative stress by decreasing reduced glutathione levels, antioxidant enzyme activity and increasing lipid peroxidation and brain protein contents. L-ascorbic acid attenuated both Pb induced neuronal oxidative stress, and abnormalities in behaviour. But L-tryptophan ameliorated Pb altered neurobehaviour with no significant effect on Pb induced oxidative stress in the brain. Co-administration of L-ascorbic acid and L-tryptophan on Pb exposed rats showed a reversal in all indices assessed towards the physiological state of control.
  
  
  CONCLUSIONS
  This suggests that L-ascorbic and L-tryptophan can be used to compliment chelating therapy in lead neurotoxicity.
authors.affiliation: Department of Biochemistry, College of Medicine, University of Lagos, Lagos, Nigeria. ebuehi@yahoo.com
authors.forename: Osaretin Albert Taiwo
authors.initials: OA
authors.lastname: Ebuehi
authors.affiliation: Department of Biochemistry, College of Medicine, University of Lagos, Lagos, Nigeria.
authors.forename: Oluseyi Cyril
authors.initials: OC
authors.lastname: Ayinde
mesh_terms: D000374:Aggression / Q000187:drug effects*; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology*; D001921:Brain / Q000503:physiopathology; D020263:Lead Poisoning, Nervous System / Q000503:physiopathology* / Q000662:veterinary; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009929:Organ Size / Q000187:drug effects; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D010544:Peroxidases / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism; D014364:Tryptophan / Q000494:pharmacology*
chemical_list: D018696:Neuroprotective Agents; D012701:Serotonin; D014364:Tryptophan; D010544:Peroxidases; D001205:Ascorbic Acid