Analysis of 5-HT and cortisol levels
To determine 5-HT level, a high-pressure liquid chromatography (HPLC) method (Serotonin Kit, Recipe, Germany) with an Alliauce Waters 465 HPLC (Waters, USA) was used. Cortisol level was determined using a CORTISOL RIA CT (AMP, Germany) with a γ-counter COBRA 5010 QUANTUM (PACKARD, USA).