Gly14]-Humanin offers neuroprotection through glycogen synthase kinase-3β inhibition in a mouse model of intracerebral hemorrhage

Abstract

Perihematomal brain edema formation and consequent cell death contribute to second brain injury resulting in severe neurological deficits and sometimes delayed fatality after intracerebral hemorrhage (ICH). [Gly14]-Humanin (HNG), a variant of Humanin (HN) in which the 14th amino acid serine is replaced with glycine, reduced Alzheimer's disease-relevant insults and improved neurological deficits in an ischemia stroke model. In the study, we aimed to evaluate whether HNG posttreatment attenuated early brain injury after ICH and whether the protective effect was associated with regulation of apoptosis via phosphatidylinositol 3-kinase (PI3K)-Akt/GSK-3β signaling. Male ICR mice were subjected to infusion of Type IV collagenase (to induce ICH) of saline (for shams) into the left striatum. ICH animals received vehicle, HNG (1 or 2.5μg in 100μl saline) administration intraperitoneally 1h post injury. Compared with vehicle, HNG-2.5μg treatment improved neurological outcome and reduced brain edema at 24 and 72h after surgery (P<0.05), but wortmannin (15μg/kg, 90min before HNG-2.5μg, intravenously) obliterated the effect. HNG-2.5μg also reduced cell insults and injury volume at 24 and 72h after surgery (P<0.05, vs. vehicle). Furthermore, HNG-2.5μg treatment increased p-Akt and Bcl-2 and decreased p-GSK-3β, cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase expressions in the ipsilateral hemisphere (P<0.05, vs. vehicle), however, the effect was reversed by wortmannin. In conclusion, HNG treatment improved functional and morphological outcomes after experimental ICH in mice and the protective effect was associated with suppressing apoptosis through PI3K-Akt/GSK-3β signaling pathway.