Post-Ischemic Helium Provides Neuroprotection in Rats Subjected to Middle Cerebral Artery Occlusion-Induced Ischemia by Producing Hypothermia

Abstract

During the past decade, studies on the manipulation of various inhaled inert gases during ischemia and/or reperfusion have led to the conclusion that inert gases may be promising agents for treating acute ischemic stroke and perinatal hypoxia-ischemia insults. Although there is a general consensus that among these gases xenon is a golden standard, the possible widespread clinical use of xenon experiences major obstacles, namely its availability and cost of production. Interestingly, recent findings have shown that helium, which is a cost-efficient inert gas with no anesthetic properties, can provide neuroprotection against acute ischemic stroke in vivo when administered during ischemia and early reperfusion. We have investigated whether helium provides neuroprotection in rats subjected to middle cerebral artery occlusion (MCAO) when administered after reperfusion, a condition prerequisite for the therapeutic viability and possible clinical use of helium. In this study, we show that helium at 75 vol% produces neuroprotection and improvement of neurologic outcome in rats subjected to transient MCAO by producing hypothermia on account of its high specific heat as compared with air.

The protective profile of argon, helium, and xenon in a model of neonatal asphyxia in rats*

“…Similar to xenon, argon and helium have shown neuroprotective qualities in vitro (11)(12)(13)(14) and in vivo (13,19) while other members of noble gas family, neon and krypton, lack effect (11). Interestingly helium has also been reported to exhibit both detrimental as well as protective effects (11)(12)(13). However, a study to comparing the neuroprotective potency of these three gases argon, helium and xenon in vivo is not available to date.…”

Protein-Noble Gas Interactions Investigated by Crystallography on Three Enzymes - Implication on Anesthesia and Neuroprotection Mechanisms

“…Despite this, the widespread clinical use of xenon is limited by its scarceness and excessive cost of production, even if close xenon delivery systems are now being developed. Using a mixture of xenon and another anesthetic gas like nitrous oxide (Marassio et al, 2011), argon (David et al, submitted), or helium (David et al, 2009) could combine the efficiency of xenon and the low cost and availability of the second gas and is thought to be a cost-efficient strategy. Argon is an inert gas which is easily available and has no narcotic nor anesthetic action at ambient pressure.…”

Drug-Induced Hypothermia in Stroke Models: Does it Always Protect?

“…Helium is one such example; it is a colorless, nontoxic and cost-efficient gas without anesthetic properties [110]. A concentration of 75 % helium in oxygen induces hypothermia in rats [111,112] and the magnitude of hypothermia correlates positively with the temperature of the gas mixtures [111,112]. Both intra-ischemic and immediately post-ischemic inhalation of helium alleviates neurological deficits in rats subjected to MCAO [107,112].…”

“…Both intra-ischemic and immediately post-ischemic inhalation of helium alleviates neurological deficits in rats subjected to MCAO [107,112]. Protection was elicited when the gas temperature was 25 °C but lost when the gas temperature was 33 °C [112]. Furthermore, late helium treatment administered 30-60 min after reperfusion?…”