Intranasal Application of Diluted Saline Alleviates Ischemic Brain Injury in Association with Suppression of Vasopressin Neurons

Abstract

Plain Language SummaryNeuroendocrine disorders during cerebral stroke are a major etiology of ischemic brain injury that occurs following the occlusion of the cerebral artery. A hypothalamic neuropeptide, antidiuretic hormone or vasopressin (VP), is a key neuroendocrine factor in ischemic brain injury. To identify the way to reduce the overly produced VP following the stroke, this study used a rat model of cerebral stroke and tested the effects of intranasal application/drops of low concentration saline-0.09% NaCl (IAL) on VP neuronal activity that determines VP secretion. The results revealed for the first time that IAL inhibition of stroke-evoked VP neuronal activation and its associated brain damage is related to IAL inhibition of ischemia-evoked astrocytic process retraction around VP neurons and increase in excitatory inputs on VP neurons from the mitral cells in the activated olfactory bulb in the ischemic side. Similar but weaker effects also occurred at oxytocin neurons that co-exist with VP neurons but exert neural protective effects. These findings highlight that IAL (or commercially available purified water?) inhibition of VP neuronal activity may provide a simply available protective strategy in the early stage of cerebral stroke after further clinical trials.