Therapeutic hypothermia combined with hydrogen sulfide treatment attenuated early blood–brain barrier disruption and brain edema induced by cardiac arrest and resuscitation in rat model

Brain injury remains a major problem in patients suffering cardiac arrest (CA). Disruption of the blood-brain barrier (BBB) is an important factor leading to brain injury. Therapeutic hypothermia is widely accepted to limit neurological impairment. However, the efficacy is incomplete. Hydrogen sulfide (H 2 S), a signaling gas molecule, has protective effects after cerebral ischemia/reperfusion injury. This study showed that combination of therapeutic hypothermia and hydrogen sulfide after resuscitation was more beneficial for attenuated BBB disruption and brain edema than that of hypothermia or hydrogen sulfide treatment alone. CA was induced by ventricular fibrillation for 4 minutes. Therapeutic hypothermia was performed by applying alcohol and ice bags to the body surface under anesthesia. We used sodium hydrosulphide (NaHS) as the H 2 S donor. Here, we found that global brain ischemia induced by CA and CPR resulted in brain edema and BBB disruption; therapeutic hypothermia or H 2 S treatment diminished brain edema, decreased the permeability and preserved the structure of BBB during the early period of CA and resuscitation, and more importantly, improved the neurologic function, increased the 7-day survival rate after resuscitation; the combination of therapeutic hypothermia and H 2 S treatment was more beneficial for reducing BBB permeability and brain edema than that of hypothermia or H 2 S treatment alone. The beneficial effects were associated with the inhibition of matrix metalloproteinase-9 (MMP-9) expression, attenuated the degradation of the tight junction protein occludin, and subsequently protected the structure of BBB. These findings suggest that combined use of hypothermia and H 2 S treatment during resuscitation of cardiac arrest patients could be a potential strategy to improve clinical outcomes and survival rate.