Erythropoietin protects from post-traumatic edema in the rat brain

Erythropoietin (Epo) is gaining interest in various neurological insults as a possible neuroprotective agent. We determined the effects of recombinant human Epo (rhEpo, 5000 IU per kg bw) on brain edema induced in rats by traumatic brain injury (TBI; impact-acceleration model; rhEpo administration 30 mins after injury). Magnetic resonance imaging (MRI) and a gravimetric technique were applied. In the MRI experiments, the apparent diffusion coefficient (ADC) and the tissue T₁ relaxation time were measured hourly in the neocortex and caudoputamen, during a 6 h time span after TBI. In the gravimetric experiments, brain water content (BWC) was determined in these two regions, 6 h after TBI. Apparent diffusion coefficient measurements showed that rhEpo decreased brain edema early and durably. Gravimetric measurements showed that rhEpo decreased BWC at H₆ in the neocortex as well as in the caudoputamen. No significant differences in ADC, in T₁, or in BWC were found between rhEpo treated-TBI rats and sham-operated rats. Our findings show that post-traumatic administration of rhEpo can significantly reduce the development of brain edema in a model of diffuse TBI. Further studies should be conducted to identify the biochemical mechanisms involved in these immediate effects and to assess the use of rhEpo as a possible therapy for post-traumatic brain edema.