Effect of Maternal Stress Prior to Conception on Hippocampal BDNF Signaling in Rat Offspring

Environmental factors, especially stress, can remain pervasive effects across the lifespan. Traumatic experiences are risk factors for the behavioral and emotional disorders. Since brain-derived neurotrophic factor (BDNF) is the important regulator of neural survival, development, and its genetic and epigenetic alterations which have been linked with several neuropsychiatric disorders, the present study investigated the effect of maternal adulthood stress on molecular changes of BDNF and tyrosine kinase-coupled receptor (TrkB) in the hippocampus of 30-day-old offspring. To induce stress, we employed a repeated forced swimming model for female rats across 21 days. Then, they were divided into two parental breeding groups: stressed mother (SM) and non-stressed mother (NSM) or control group. Anxiety-like behavior was tested in adult female rats and 30-day-old pups by using the elevated plus maze (EPM). The level of serum corticosterone was also measured by ELISA. BDNF and TrkB gene methylation and protein expression in the hippocampus were detected using real-time PCR and Western blotting in all groups. Thirty-day-old male and female pups from SM groups had a significantly more serum corticosterone concentration, DNA methylation levels of BDNF and TrKB, and lower expression of these genes compared to pups from the control groups. Also, male pups from stressed mother exhibited significant anxiety-like behavior compared to male pups from the control mothers. These findings suggest that molecular changes formed by maternal stress experience even before conception persist to the next generation and will negatively influence on phenotypes of offspring.