Selection and dynamic metabolic response of rat biomarkers by metabonomics and multivariate statistical analysis combined with GC–MS.

doi: http://dx.doi.org/10.1016/j.pbb.2013.12.013

By Gao, Xiaoxia; Guo, Bingrong; Yang, Lan; Liu, Jiali; Zhang, Xiaoqin; Qin, Xuemei; Du, Guanhua

Pharmacology, Biochemistry and Behavior, Vol 117, Feb 2014, 85-91.

Early-life stress and antidepressants modulate peripheral biomarkers in a gene–environment rat model of depression.

doi: http://dx.doi.org/10.1016/j.pnpbp.2010.05.019

By Carboni, Lucia; Becchi, Serena; Piubelli, Chiara; Mallei, Alessandra; Giambelli, Roberto; Razzoli, Maria; Mathé, Aleksander A.; Popoli, Maurizio; Domenici, Enrico

Progress in Neuro-Psychopharmacology & Biological Psychiatry, Vol 34(6), Aug 16 , 2010, 1037-1048.

See the link below for some interesting recent work on tryptophan and kynurenine pathway and biomarkers.

http://www.sciencedirect.com/science/article/pii/S0092867414010496

I would think that elevated cortisol would be present.