Protective effects of hydrogen gas against spinal cord ischemia-reperfusion injury

J Thorac Cardiovasc Surg. 2021 May 4;S0022-5223(21)00762-5. doi: 10.1016/j.jtcvs.2021.04.077. Online ahead of print.

Abstract

Objective: This experimental study aimed to assess the efficacy of hydrogen gas inhalation against spinal cord ischemia-reperfusion injury and reveal its mechanism by measuring glutamate concentration in the ventral horn using an in vivo microdialysis method.

Methods: Male Sprague-Dawley rats were divided into the following 6 groups: sham, only spinal ischemia, 3% hydrogen gas (spinal ischemia + 3% hydrogen gas), 2% hydrogen gas (spinal ischemia + 2% hydrogen gas), 1% hydrogen gas (spinal ischemia + 1% hydrogen gas), and hydrogen gas dihydrokainate (spinal ischemia + dihydrokainate [selective inhibitor of glutamate transporter-1] + 3% hydrogen gas). Hydrogen gas inhalation was initiated 10 minutes before the ischemia. For the hydrogen gas dihydrokainate group, glutamate transporter-1 inhibitor was administered 20 minutes before the ischemia. Immunofluorescence was performed to assess the expression of glutamate transporter-1 in the ventral horn.

Results: The increase in extracellular glutamate induced by spinal ischemia was significantly suppressed by 3% hydrogen gas inhalation (P < .05). This effect was produced in increasing order: 1%, 2%, and 3%. Conversely, the preadministration of glutamate transporter-1 inhibitor diminished the suppression of spinal ischemia-induced glutamate increase observed during the inhalation of 3% hydrogen gas. Immunofluorescence indicated the expression of glutamate transporter-1 in the spinal ischemia group was significantly decreased compared with the sham group, which was attenuated by 3% hydrogen gas inhalation (P < .05).

Conclusions: Our study demonstrated hydrogen gas inhalation exhibits a protective and concentration-dependent effect against spinal ischemic injury, and glutamate transporter-1 has an important role in the protective effects against spinal cord injury.

Keywords: glutamate transporter-1; hydrogen gas; in vivo microdialysis; ischemia–reperfusion injury; neuroprotection.