Sex and region difference of the expression of ERK in prenatal stress offspring hippocampus

Prenatal stress is known to cause neuronal loss and oxidative damage in the hippocampus of offspring rats. The underlying molecular mechanism has not been fully understood. The extracellularsignal-regulated kinase (ERK1/2) is recruited when the brain undergoes synaptic plasticity and remodeling. In the present study, we used Western blotting and immunohistochemistry techniques to examine the effects of prenatal restraint stress (PNS) on the expression of phosphorylated ERK (p-ERK) and total ERK. Pregnant rats in the PNS group were exposed to restraint stress on day 14–20 of pregnancy three times daily for 45 min. One-month-old offspring rats were used in this experiment. PNS treatment increased the expression of p-ERK2 compared to that in the control female offspring rats and total ERK2 in female offspring hippocampus compared with that of control group. No significant changes in the amounts of total ERK1 of prenatally offspring hippocampus were observed in both genders compared with control animals. ERK immunodensity was significantly increased in PNS groups in CA3 field in male offspring hippocampus compared with control animals. ERK optical density was significantly increased in PNS female offspring hippocampus CA1, CA3 and CA4 region. However, ERK optical density was not significantly different between male control and PNS groups in CA1, CA4 fields and DG in offspring hippocampus. These findings suggest the sex and region-dependent effects of prenatal stress on the expression of ERK in offspring hippocampus. ERK expression changes induced by prenatal stress may contribute to hippocampus synaptic plasticity changes of the offspring.