Effects of caffeine on neuronal apoptosis in neonatal hypoxic-ischemic brain injury

Hypoxia-ischemia (HI) in rat pups leads to strong activation of apoptosis, and apoptosis contributes significantly to cerebral damage in the perinatal period. Caffeine displays a broad array of actions on the brain. The aim of this study was to investigate the effects of caffeine on neuronal apoptosis in a hypoxic-ischemic neonatal model.

Twenty-four seven-day-old Wistar rat pups were subjected to right common carotid artery ligation and hypoxia for 2 h. Sham group (n = 8) had a median neck incision, but the rats were not subjected to ligation or hypoxia. The pups were treated with 20 mg/kg/day caffeine citrate (n = 8) or saline (n = 8) immediately before HI and at 0, 24, 48 and 72 h post-hypoxia. Neuronal apoptosis was evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) and caspase-3 in the hippocampus and parietal cortex of both hemispheres.

The numbers of apoptotic cells in the hippocampus and parietal cortex were significantly higher in the saline group than they were in the sham group (p < 0.0001). The number of apoptotic cells in the hippocampus (p < 0.0001) and parietal cortex (p < 0.0001, TUNEL and p = 0.001, caspase-3) were higher in the caffeine-treated group than they were in the sham group, but the number of apoptotic cells decreased significantly in the caffeine-treated group compared with the saline group in the hippocampus (p < 0.0001, TUNEL and p = 0.001, caspase-3) and parietal cortex (p = 0.001, TUNEL and p = 0.002, caspase-3).

We show that caffeine administration in hypoxic-ischemic brain injury reduces neuronal apoptosis in the developing brain. We suggest that caffeine may be effective in reducing brain injury.