Assessment of the dose-dependent effect of tryptophan on anxiety with electrodermal activity and elevated plus maze test in mice

Dolu N., Özesmi Ç.

Klinik Psikofarmakoloji Bulteni, vol.17, no.2, pp.74-79, 2007 (Scopus) identifier identifier

  • Publication Type: Article / Article
  • Volume: 17 Issue: 2
  • Publication Date: 2007
  • Journal Name: Klinik Psikofarmakoloji Bulteni
  • Journal Indexes: Scopus, TR DİZİN (ULAKBİM)
  • Page Numbers: pp.74-79
  • Keywords: Anxiety, Electrodermal activity, Mice, Plus maze, Tryptophan
  • Istanbul Medipol University Affiliated: No


Objective: Administration of tryptophan (TRP) may cause an anxiolytic effect. However, there is a lack of conclusive evidence for dose-dependent effect of L- tryptophan (L-TRP) against anxiety. To assess the dose-dependent acute effect of external administration of a single dose L- tryptophan (L-TRP) on anxiety, we investigated these effects with electrodermal activity (EDA) and elevated plus maze. Methods: 45 mice were divided into 3 groups. L-TRP was injected to two different experimental groups of mice with doses at 250 and 500 mg/kg i.p. (respectively, group 1 and 2) Physiological saline was injected to the control group. The anxiety score of the mice were measured with elevated plus maze 30 minutes after injection. Then Skin Conductance Level (SCL), which is a tonic EDA parameter, was measured. Shorter duration in open arms and higher SCL indicate higher anxiety. Results: In Group 1, SCL was higher than control group (p<0.05). Group 1 demostrated an anxiogenic effect. In Group 2, while SCL was lower than Group 1, the mean time spent in the open arms was higher than this group (p<0.05). Group 2 demostrated anxiolytic effect. Conclusion: This study showed that L-TRP results in anxiogenic behavior based on plus maze and EDA at 250 mg/kg i.p. At a high dose of L-TRP, this anxiogenic effect disappeared. The anxiety-like effect of L-TRP depends on its dose-related effect. However, this is a preliminary study and future evaluations are needed to confirm these anxiolytic effects in different L-tryptophan doses.