Previously, we showed that a transient early-in-life interference with the expression of multiple genes by mithramycin (MTR) followed by later-in-life exposure to chronic stress, leads to a "daring" and novelty seeking behavior in rats. In this study we searched for molecular changes that contribute to this behavioral alteration. We applied a non-hypothesis driven strategy using whole genome cDNA array analysis (WGA) followed by Genome Scale Metabolic modeling analysis (GSMM). Gene expression validation was performed by qRT-PCR and immunoblotting. Brain and serum amino acids levels were measured by HPLC. WGA data directed us towards metabolic pathways and GSMM pointed at branched chain amino acids (BCAA) pathway. Out of 21 amino acids analyzed in the prefrontal cortex of MTR+Stress rats only tryptophan, whose brain levels depend on serum BCAA levels, showed a significant decrease. No change was observed in serotonin or kynurenine levels. However, a significant reduction in mRNA and protein levels of the large neutral amino acid transporter (LAT1), which transports BCAA and tryptophan into the brain, as well as in serum levels of tryptophan/BCAA ratio were observed. The latter may be attributed to the failure to increase serum insulin, following stress, in rats pre-exposed to mithramycin. Finally, significant correlations were observed between the anxiety index and tryptophan and between T-maze errors and LAT1. This study shows a specific behavioral pattern, which is linked to modulations in fluxes of amino acids both peripheral and central, which converge and reciprocally interact, and may thus be equally important targets for therapeutic intervention.
Bibliographical noteFunding Information:
This study was supported by a grant from the Rappaport Family Institute for Research in the Medical Sciences Foundation and by Vincent Mayer Donation . We thank Dr. Liat Linde and Dr. Nili Avidan from The Genomics Core Facility at the Rappaport Faculty of Medicine, Technion, for genomics and data analysis services
This study was supported by a grant from the Rappaport Family Institute for Research in the Medical Sciences, Technion, Haifa Israel, and by Vincent Mayer Donation. None had any role in study design, in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication.
© 2015 Elsevier B.V. and ECNP.
- Essential amino acids
- Gene-environmental interaction
ASJC Scopus subject areas
- Clinical Neurology
- Psychiatry and Mental health
- Biological Psychiatry
- Pharmacology (medical)