Endothelin-1 mediated vasoconstriction leads to memory impairment and synaptic dysfunction

Cerebrovascular lesions seen as white matter hyperintensity in MRI of elderly population caused due to micro-infracts and micro-bleeds contributes to vascular dementia. Such vascular insult caused by impairment in blood flow to specific area in brain involving small vessels can gradually worsen the pathology leading to cognitive deficits. In the present study we developed a transient model of vaso-constriction to study the impact of such pathology by bilateral injection of ET-1 (Endothelin-1; a 21 amino acid vasoconstricting peptide) into lateral ventricles of C57 mice. The impediment in cerebral blood flow decreased CD31 expression in endothelial cells lining the blood vessels around the hippocampal region, leading to memory deficits after 7 days. Activity dependent protein translation, critical for synaptic plasticity was absent in synaptoneurosomes prepared from hippocampal tissue. Further, Akt1- mTOR signaling cascade was downregulated indicating the possible cause for loss of activity dependent protein translation. However, these effects were reversed after 30 days indicating the ephemeral nature of deficits following a single vascular insult. Present study demonstrates that vasoconstriction leading to memory deficit and decline in activity dependent protein translation in hippocampus as a potential molecular mechanism impacting synaptic plasticity.