Effects of local hypothermia on neuronal cell apoptosis after intracerebral hemorrhage in rats

Intracerebral hemorrhage (ICH) is a devastating subtype of stroke that is characterized by significant morbidity and mortality. Thus far, there is no effective treatment option for spontaneous ICH. In this study, we aimed to investigate the effects of local hypothermia on brain injuries after ICH. Bacterial collagenase was used to induce ICH stroke in male Wistar rats. We assessed the effects of normothermia and 4 hours of local hypothermia (similar to 33.2A degrees C) initiated 1 hour after collagenase infusion on the neurological outcomes and brain water content at 1 and 3 days after ICH. The pathological changes of neuronal ultrastructure were examined with transmission electron microscopy. Furthermore, the expression levels of apoptotic molecules and matrix metalloproteinases-9 (MMP-9) were determined using western blotting and immunohistochemical staining. Local hypothermia tends to reduce neurological deficits compared with the normothermic group at day 3 after ICH. Transmission electron microscopy reveals that local hypothermia significantly improves the ultrastructural outcomes at 1 and 3 days after ICH. In addition, local hypothermia markedly reduces edema formation and the expression levels of MMP-9 and apoptotic signal. These data suggest that local hypothermia induces a reduction in the brain edema and partly reduces neurological deficits along with marked inhibitory effects on MMP-9 and cell apoptosis after ICH.