Hydrogen Sulfide Ameliorates Lipopolysaccharide-Induced Memory Impairment in Mice by Reducing Apoptosis, Oxidative, and Inflammatory Effects.

Hydrogen sulfide (HS) is reported to have a neuroprotective activity; however, the role of HS in neuroinflammation-induced neuronal damage is ambiguous. Here, we aimed to evaluate the underlying mechanisms for the neuroprotective effect of NaHS, a known HS donor, against lipopolysaccharide (LPS)-induced memory impairment (MI). All the treatments were administered for 28 days, and LPS (0.25 mg/kg i.p.) was co-administered intermittently for 7 days from days 15 to 21. Morris water maze (MWM) and Y-maze tests were performed to evaluate MI. Neurodegeneration was histopathologically examined, and the brain homogenates were characterized for reduced glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA), tumor necrosis factor (TNF)-α, interleukin (IL)-6, caspase-3, c-Jun, and acetylcholinesterase (AChE) by biochemical analysis. HS administration significantly improved spatial and working memory in MWM and Y-maze tasks, respectively. Exogenous HS significantly reversed LPS-induced oxidative stress as evidenced by improved GSH, MDA, and SOD levels. HS pretreatment significantly attenuated LPS-induced apoptosis and inflammation by decreasing c-Jun and caspase-3 levels and inhibiting TNF-α and IL-6, respectively. The decrease in these markers was supported by H&E and Nissl staining, which confirmed the anti-necrotic activity of HS. However, there was no significant improvement in LPS-induced increase in AChE activity. These results indicate that chronic systemic inflammation leads to neurodegeneration and MI and HS exerts its neuroprotective effect due to its anti-oxidative, anti-inflammatory, and anti-apoptotic potential via modulation of JNK and extrinsic apoptosis pathways.