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

Background: 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.

Objective: To investigate the effects of pharmacological modulation using mitochondrial fusion promoter (M1) in the brain of rats following cardiac I/R injury.

Methods: 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.

Results: 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.

Conclusion: This mitochondrial fusion promoter significantly protected rats with cardiac I/R injury against brain damage.