Neopterin-tetrahydrobiopterin pathway related to inflammatory and nitric oxide levels in adolescents with major depressive disorder

Aim: In spite of many ongoing and completed studies on the biological mechanisms that contribute to the pathophysiology of Major Depressive disorder, the pathophysiology of MDD is still unclear. In this study, it was aimed that to compare healthy controls with major depressive disorder patients' serum neopterin, tetrahdirobiopterin, serotonin, tryptophan, NO levels in the neopterin-tetrahdirobiopterin pathway and IL-2 levels thought to stimulate this pathway. In addition, the neopterin pathway and cytokine relationship was evaluated. Method: 40 patients with major depressive disorder who did not use psychotropic drugs and 37 healthy controls were included in the study. Serum neopterin, tetrahydrobiopterin, serotonin, tryptophan, NO, IL-2 levels were measured by ELISA (enzymelinked immunosorbent assay) method. Results: The results of the comparisons in between MDD and healthy control group showed that, the neopterin levels were significantly lower in patients in depressions than healthy patients (p<0,001). In MDD patients IL-2 levels were lower than control patients, but difference were statistically insignificant (p value is very close to statistical significance. p=0.051). The tetrahydrobiopterin levels were found lower in MDD patients than healthy patients (p=0,042) and the difference between two groups was found statistically insignificant in terms of serotonin (p=0,403), triptofan (p=0,062) and NO (p=0,617) levels. Conclusion: In conclusion, according to these obtained results, it is observed that the neopterin-tetrahydrobiopterin pathway does not have a part in the pathophysiology of depression in adolescents. The findings support the relationship between adolescent depression and HPA axis. In order to elucidate the depression pathophysiology in adolescents, further studies needs to be conducted on both neopterin-tetrahydrobiopterin and HPA axis relation with depression. Key words: neopterin, serotonin, cytokine, inflammation, NO, depression