Abstract 305
Neonatal Disease Oriented Research: Steroids & Oxygen: Perinatal Effects Poster Symposium, Sunday, 5/2
Synthetic glucocorticoids (GC) are widely used for the prevention of chronic lung disease after severe respiratory distress syndrome in premature infants. This treatment may interfere with the development of the immature brain. Little is known about the long-term consequences for cognitive functioning of these children in later life. The present study investigated the long-term effects of neonatal treatment with clinically relevant doses of GC on spatial learning performance in the Morris water maze in adult rats. Rat pups were treated (i.p.) with dexamethasone-phosphate (DEX-group) on postnatal day 1 (0.5 µg/g), day 2 (0.3 µg/g) and day 3 (0.1 µg/g). Control pups were treated with equivalent doses of saline (SAL-group), or left untreated (UNTR-group). At 14 weeks of age, spatial learning performance was tested by giving a 3 acquisition trials daily on 5 consecutive days. During the acquisition rats learned to locate a submerged platform in the water maze only by its position to extra-maze cues. Rats treated neonatally with DEX had a impaired performance (p=0.03) as compared with the rats of the SAL-group. Once the rats had learned to find the platform, no differences (p=0.8) in performance between the groups were observed (tested 3 days after acquisition). To reveal if deficits in sensorimotor processes could account for the impaired performance, another group of rats was tested in the water maze with a visible platform, which does not require spatial orientation. The performance in this test was similar (p=0.7) in rats of the DEX-, SAL- and UNTR-group. In conclusion, early neonatal DEX treatment results in an impaired performance during the acquisition of a spatial learning task in adult rats. Our data suggest that early GC treatment in preterm infants may have consequences for cognitive functioning in later life.
