Background and Aim Dexamethasone (Dex) is widely used to prevent chronic lung disease in premature infants. Evidence emerges that Dex has a wide range of adverse effects. Earlier studies have shown that this also involves cognition and behaviour (Yeh 2004; Karemaker 2006). The hippocampus is known to play a critical role in cognition and behaviour. We performed a histopathological and quantitative study on the hippocampus of rats after Dex. We hypothesized that neonatal Dex alters normal hippocampal growth.

Methods Rat pups received Dex or saline (control) on day 1, 2 and 3 (0.5, 0.3 and 0.1 mg/kg). At 50 weeks rats were sacrificed and anatomical data collected. Brain tissue was stained with H&E and total number and number of damaged neurons in the hippocampus was determined.

Results Brain weight was lower in Dex rats. Number of neurons did not differ, but the number of damaged neurons in the hippocampus was significantly increased in the Dex rats (p<0.01) (table).

Conclusion

This study confirms the serious long-term adverse effects of Dex and explains the behavioural and cognitive abnormalities in neonatally Dex-treated children.