Neuroprotective Potential of Nitroglycerin in Ischemic Stroke: Insights into Neural Glucose Metabolism and Endoplasmic Reticulum Stress Inhibition.

Background: Glyceryl trinitrate (GTN), also known as nitroglycerin, is predominantly recognized as a vasodilator for ischemic heart disease, and its potential neuroprotective properties in acute ischemic stroke remain under exploration. We sought to discover the therapeutic advantages and mechanisms of post-recanalization GTN administration in acute ischemic stroke.
Methods and Results: A total of 118 male Sprague-Dawley rats were divided into groups: sham, transient/permanent middle cerebral artery occlusion (MCAO) with or without GTN treatment, and transient/permanent MCAO treated with both GTN and KT5823, an inhibitor of PKG. Acute ischemic stroke was induced by transient MCAO for 2 hours followed by 6 or 24 hours of reperfusion and permanent MCAO (28-hour MCAO without reperfusion). The study assessed infarct volumes, neurological deficits, glucose metabolism metrics, NO, and cGMP levels via ELISA. mRNA and protein expression of key molecules of hyperglycolysis, gluconeogenesis, endoplasmic reticulum stress as well as signaling molecules (PKG, AMPK) were conducted via reverse transcription polymerase chain reaction and Western blotting, and cell death was assessed with TUNEL and ELISA. GTN significantly reduced cerebral infarct volumes, neurological deficits, and cell death only after transient MCAO. GTN led to a significant reduction in the expression of NO and cGMP levels, key glucose metabolism, endoplasmic reticulum stress-related genes and proteins, and phosphorylated AMPK while boosting PKG expression, in transient MCAO but not permanent MCAO. The GTN-induced reduction in glucose metabolites, lactate, and reactive oxygen species was exclusive to transient MCAO groups. Coadministration of GTN and PKG inhibitors reversed the observed GTN benefits.
Conclusions: GTN induced neuroprotection in transient MCAO by improving glucose metabolism and potentially controlling endoplasmic reticulum stress through the NO-cGMP-PKG signaling cascade to inhibit AMPK phosphorylation.