Background and purpose: Intracerebral hemorrhage (ICH) is mostly a disease of the elderly, but most current experimental ICH models have used young animals. Age is an important factor in other forms of brain injury, affecting microglia and astrocyte reactions and plasticity. Therefore, the present study investigated the effects of aging on brain injury after ICH.
Methods: Young and aged (3 and 18 months old, respectively) male Sprague-Dawley rats received an intracerebral infusion of 100 microL autologous blood. Age-related changes in brain swelling, glial reaction, stress protein (heat shock proteins [HSPs] 27 and 32), and neurological deficits were examined.
Results: Brain swelling was more severe in old rats compared with young rats at 3 days after ICH (P<0.05). There were also more severe neurological deficits in the older rats at 1 day after ICH, which persisted for the 4 weeks of monitoring (P<0.05). The older rats also had stronger microglial activation and a greater perihematomal induction of HSP-27 and HSP-32 (P<0.05). In contrast, there was a weaker astrocytic reaction to the hematoma.
Conclusions: ICH causes more severe brain swelling and neurological deficits in old rats. Clarification of the mechanisms of brain injury after ICH in the aging brain should help develop new therapeutic strategies for hemorrhagic brain injury.