Maternal Stress during Pregnancy in Mice Induces Sex-Dependent Behavioral Alterations in Offspring along with Impaired Serotonin and Kynurenine Pathways of Tryptophan Metabolism.

Maternal stress during pregnancy results in increased risk of developing psychiatric disorders in the offspring including anxiety, depression, schizophrenia, and autism. However, the mechanisms underlying this disease susceptibility remain largely to be determined. In this study, the involvement of the serotonin (5-HT) and kynurenine (KYN) pathways of tryptophan metabolism on the behavioral deficits induced by maternal stress during the late phase of gestation in mice was investigated. Adult offspring born to control or restraint-stressed dams were exposed to the elevated plus-maze and tail suspension tests. Metabolites of the KYN and 5-HT pathways were measured in the hippocampus and brainstem by ultra-performance liquid chromatography tandem mass spectrometry. Female, but not male, prenatally stressed (PNS) offspring displayed a depressive-like phenotype, mainly when in proestrus/diestrus, along with reduced hippocampal 5-HT levels and high 5-HT turnover rate in the hippocampus and brainstem. In contrast, male PNS mice showed enhanced anxiety-like behaviors and higher hippocampal and brainstem quinolinic acid levels compared to male offspring born to nonstressed dams. These results indicate that maternal stress affects the behavior and brain metabolism of tryptophan in the offspring in a sex-dependent manner and suggest that alterations in both the 5-HT and KYN pathways may underlie the emotional dysfunctions observed in individuals exposed to stress during in utero development.