Abstract 3432: Sex-dependent Differences in Autophagy After Experimentally-induced Stroke
Background and Purpose: Autophagy is a catabolic process where the cell consumes pieces of itself as a part of normal cellular growth, development, and homeostasis. In response to nutrient challenge or other stressors, including ischemia, autophagy levels may rise, enabling the cell to survive. Autophagy has been shown to play a role in the cellular response to neonatal cerebral ischemia, and sex differences have been found in cell culture models of neuronal nutrient starvation. However, the role of sex in the autophagic response to stroke has not been investigated in vivo. The objective of this study was to examine the impact of sex on autophagy following experimental stroke.
Methods: Stroke was induced by reversible right middle cerebral artery occlusion (MCAO - 90 minutes) in male, gonadally-intact female, and ovariectomized (OVX) WT C57BL/6 mice (20-25 gm). Autophagy activity was assessed at 6 and 24 hours following MCAO with LC3-I/II and Atg7 protein levels by western blot (n=3 MCAO; n=3 sham/group). Beta-actin was utilized as a loading control.
Results: Atg7 levels were higher in sham males at both the 6h and 24h timepoint compared to intact females and OVX females. After MCAO, males and OXV females showed increased levels of Atg7 relative to sham at 6h, while intact female levels were unchanged. By 24h, Atg7 levels in MCAO males and OVX females remained higher than sham, while intact females showed no difference. LC3-II levels were higher in MCAO for OVX females at 6h and 24h, while intact females saw transiently-elevated LC3-II levels at 6h and no elevation by 24h. Males had higher levels of LC3-II in both MCAO and sham relative to intact females at both 6h and 24h and higher levels than OVX females at 6h.
Conclusions: This study demonstrates that autophagy activation in response to stroke differs between the sexes. We found that males had overall higher levels of autophagy than both OVX females and intact females at both 6h and 24h. Both males and OVX females showed higher levels of autophagy at 24h and 6h after MCAO relative to sham, while females showed no change. Our study suggests that changes in autophagy may contribute to the differential outcome after stroke between the sexes. Studies examining sex differences in infarct size after MCAO after inhibition of autophagy with 3-methyladenine (3-MA, Sigma-Aldrich, St. Louis, MO) are ongoing in our laboratory.
- © 2012 by American Heart Association, Inc.