Abstract 65: Restoration of Growth Differentiation Factor 11 Protects Against Stroke in Mice

Abstract

Introduction: GDF 11 is a member of the transforming growth factor β superfamily. Loss of GDF11 occurs with aging and declining levels correlate with several detrimental age-associated phenotypes in both peripheral tissues and brain. Restoration of GDF11 enhances neurogenesis and cognitive function in aged mice. Brain expression of GDF11 has not been investigated after stroke. Stroke differentially affects the elderly. In this work we examined the role of GDF11 in aging, stroke and its potential utility as a neuroprotective agent. Methods: Male C57/BL6NCrl young (2-3 months) and aged (19-21) mice were used. Brain GDF11 expression was evaluated in young and aged mice by western blot. Focal ischemia was induced with a transient middle cerebral artery occlusion (MCAO). Mice were randomly assigned into two groups and were subjected to 90 min MCAO. Group 1 received vehicle (phosphate buffered saline) and group 2 was administered rGDF11 (100 ug/kg., ip) at the onset of ischemia. In additional experiments, the efficacy of delayed treatment (3 h after ischemia) with rGDF11 was tested. These mice were subjected to a 60 min MCAO. Mice were euthanized after 24 hours and 7 days respectively and brains were harvested to estimate infarct area. Results: A significant decrease in brain GDF11 levels was observed in aged mice as compared to young (p<0.05). Additionally, a significant decline in brain GDF11 expression was observed after stroke at 24 hours vs. sham groups (p<0.05). A significant decrease in cortical and hemispheric infarct area was observed in the rGDF11 group (cortical 48.73±1.05; hemisphere 49.68±3.58) as compared to vehicle group (60.54±4.88; 61.35±6.03), when GDF was administered at the time of ischemia. Delayed treatment with rGDF11 also reduced infarct at 7 days. Conclusions: Brain GDF11 levels decline with age and after stroke. Supplementation with rGDF11 ameliorates stroke induced injury in young mice at 24h and 7 days. These finding suggest potential role of GDF11 in age and stroke. Restoration of age-related loss of GDF may be a viable therapy for stroke.