Mitochondrial Fusion Promoter Alleviates Brain Damage in Rats with Cardiac Ischemia/Reperfusion Injury.

Abstract

Cardiac ischemia/reperfusion (I/R) injury induces brain damage through increased blood-brain barrier (BBB) breakdown, microglial hyperactivity, pro-inflammatory cytokines, amyloid-β deposition, loss of dendritic spines, brain mitochondrial dysfunction, and imbalanced mitochondrial dynamics. Previous studies demonstrated that mitochondrial fusion promoter reduced cardiac damage from cardiac I/R injury; however, following cardiac I/R injury, the roles of mitochondrial dynamics on the brain have not been investigated. To investigate the effects of pharmacological modulation using mitochondrial fusion promoter (M1) in the brain of rats following cardiac I/R injury. Twenty-four male Wistar rats were separated into two groups; 1) sham-operation (n = 8) and 2) cardiac I/R injury (n = 16). Rats in the cardiac I/R injury group were randomly received either normal saline solution as a vehicle or a mitochondrial fusion promoter (M1, 2 mg/kg) intravenously. Both treatments were given to the rats 15 minutes before cardiac I/R injury. At the end of the reperfusion protocol, the brain was rapidly removed to investigate brain mitochondrial function, mitochondrial dynamics proteins, microglial activity, and Alzheimer's disease (AD) related proteins. Cardiac I/R injury induced brain mitochondrial dynamics imbalance as indicated by reduced mitochondrial fusion proteins expression without alteration in mitochondrial fission, brain mitochondrial dysfunction, BBB breakdown, increased macrophage infiltration, apoptosis, and AD-related proteins. Pretreatment with M1 effectively increased the expression of mitofusin 2, a mitochondrial outer membrane fusion protein, reduced brain mitochondrial dysfunction, BBB breakdown, macrophage infiltration, apoptosis, and AD-related proteins in rats following cardiac I/R injury. This mitochondrial fusion promoter significantly protected rats with cardiac I/R injury against brain damage.