EFFECTS OF MILD CHRONIC STRESS OF FEMALE RATS BEFORE AND DURING PREGNANCY ON SENSOMOTOR DEVELOPMENT, ANXIETY AND COGNITIVE FUNCTIONS OF THE OFFSPRING

Effects of mild unpredictable chronic stress of female rats during two weeks before and two weeks during pregnancy on sensorimotor development, muscle strength and coordination of movements, cognitive abilities and the level of anxiety in offspring from birth to 3 months of life were investigated. Exposure to pregestational stress led to an increase of anxiety in females by the beginning of pregnancy, which persisted during first week of lactation. Prenatal stress led to a decrease in litter size, body weight of pups, a delay in physical development, and maturation of some sensorimotor reflexes in the first two weeks after birth. Motor activity reduced in the first two weeks was restored by the 26th day of life (P); no changes in muscle strength and motor coordination were observed in P16 and P26 rats. At all analyzed ages (P16, 26, 80), a decrease in exploratory activity and an increase in the level of anxiety were observed. Impairments of learning processes, spatial and nonspatial memory were shown in Morris water maze (P21-22) and the test for recognizing a new object (P72-90). Thus, our results indicate that moderate stress in females before and during pregnancy induced not only the impaired physical and neurological development in early ontogenesis, but also an increase in the level of anxiety and cognitive dysfunctions that persist in the adult period of the offspring.