Hydrogen sulfide regulates NLRP3 to inhibit pyroptosis and protect against hypoxic-ischemic brain injury in neonatal rats

Background: Hypoxic-ischemic encephalopathy (HIE) is a leading cause of neonatal mortality and long-term neurological deficits. This study investigated whether sodium hydrosulfide (NaHS), an exogenous donor of hydrogen sulfide (H2S) could protect against HIE by inhibiting microglial activation and pyroptosis in brain tissue. Methods: A neonatal hypoxic-ischemic encephalopathy (NIE) model was established in rats via hypoxia combined with ligation of the left common carotid artery. Exogenous hydrogen sulfide (NaHS) and the nucleotide-binding oligomerization domain-, leucine-rich repeat-, and pyrin domain- containing receptor 3 (NLRP3) inhibitor CY-09 were administered post-injury. Cognitive function was assessed using the Morris water maze. Hippocampal injury was examined using Nissl staining. Microglial activation was assessed by immunofluorescence detection of Iba-1 expression. Pyroptosis-related proteins expression levels in brain tissue were measured using Western blotting. Results: Treatment with exogenous hydrogen sulfide significantly reduced neuronal injury, inhibited microglial activation, enhanced memory and spatial learning (as demonstrated by a decrease in escape latency, an increase of platform crossings, and time spent in the target quadrant). Furthermore, it suppressed the expression of NLRP3 inflammasome, Gasdermin D N-terminal domain (GSDMD-N), cleaved caspase-1, Interleukin (IL)-1β, and IL-18 proteins. Conclusions: Exogenous hydrogen sulfide mitigates neuronal damage, improves cognitive outcomes, and suppresses pyroptosis and microglial activation in neonatal rats with hypoxic-ischemic encephalopathy.