Effects of Prenatal Combined Stress on Passive Avoidance Learning and Memory in Rats

Abstract

The effects of combined prenatal stress (including the action of electromagnetic fields, zoo social stress, and immobility on pregnant females) on the learning and memory of offsprings of rats were investigated. Two groups of male and female rats (n = 16 in each) were studied. The animals received prenatally (from 8 to 18 days of gestation) three different stresses as follows: immobilization of pregnant mothers (0.5 h, twice a day by placing in a restrainer), social stress (6 rats kept in a small cage), and exposure to electromagnetic waves (4 h, 0.5 MT, 50 Hz). The learning and memory of rats were assessed two months after birth (2, 6, 24, 48 h and 1- and 2-week-long intervals after training) by using a conditioning avoidance method. Also, expression of the APP gene was investigated in rats using RT-PCR. The prenatal stress suppressed visits of male offsprings to the dark compartment in comparison with the control group, and the difference was significant 2 h after the shock (P 0.05).The relative expression of the APP gene was also higher in both male and female offsprings (P < 0.05 and 0.01, respectively). Thus, the implemented combined prenatal stress impaired the acquisition process and long-term memory in male offsprings and long-term memory in female offsprings. Also, it may promote deposition of β-amyloid plaques.