Enriched environment restricted to gestation accelerates the development of sensory and motor circuits in the rat pup.

The effects of stimulating environments on the neural plasticity of the adult brain have been well explored; however, how an enriched environment (EE) affects the mother-fetus interaction is poorly understood. We hypothesized that an enriched environment restricted to pregnancy will succeed in accelerating the development of sensory and motor circuits in the offspring. Pregnant Wistar rats were maintained either under a standard condition - two animals per standard cage- or an enriched environment - eight subjects in larger cages with different physical configurations-. After birth, litters from both groups (n=16 per group) were cross-fostered with mothers that were simultaneously maintained under standard environment during pregnancy. Sensory and motor development were studied in the pups of both groups with a battery of reflex and physical tests. Auditory and gait reflexes appeared two days earlier in the offspring of EE rats as compared to control subjects (p<0.05). In addition, EE pups displayed a better performance in righting reflex, inclined board and geotaxis tests (p<0.05). Differences were found even three weeks after birth. We conclude that EE limited to the phase of pregnancy stimulates the development of pups inutero so that they are born with a higher grade of development.