Inhibition of NMDA Receptors Downregulates Astrocytic AQP4 to Suppress Seizures.

Aquaporin 4 (AQP4), a water-specific channel protein locating on the astrocyte membrane, has been found to be antagonist, agonist and undergone closely related to epilepsy. Our previous study showed that inhibition of an N-methyl-D-aspartate receptor (NMDAR) subunit NR2A can suppress epileptic seizures, suggesting that AQP4 is potentially involved in NR2A-mediated epilepsy treatment. In this study, we aimed to explore the relevance of AQP4 in NR2A-mediated seizures treatment in pentylenetetrazol (PTZ)-induced rat models. We performed electroencephalogram (EEG) recording and examined AQP4 expression at mRNA and protein levels, and the downstream molecules of AQP4 as well. It showed that AQP4 expression was increased after the induction of seizures. Lateral ventricle pretreatment of NR2A inhibitor could mitigate the PTZ-induced seizures severity and counterbalance the increase of AQP4 expression. In contrast, NR2A activator that resulted in seizures aggravation could further augment the seizure-related elevations of AQP4 expression. Pharmacological inhibition of AQP4 alone could also suppress the PTZ-induced seizure activities, with decreased expressions of NF-κB p65, interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-α in the brain. The results indicated that increased expression of AQP4 might be an important mechanism involved in NR2A of NMDAR-mediated treatment for epileptic seizures, enlightening a potentially new target for seizures treatment.

A novel hydrogen sulfide donor reduces neuroinflammation and seizures by activating ATP-sensitive potassium channels.

Epilepsy is a common neurological disorder worldwide. Hydrogen sulfide (H2S) has been found to have anti-seizure effects. However, its mechanism remains to be explored. In the present study, we showed that a novel H2S donor attenuated neuroinflammation by up-regulating ATP-sensitive potassium channel (KATP) expression to reduce seizures. The novel H2S donor significantly reduced the expression of TNF-α and increased the expression of IL-10 in LPS-treated BV2 cells and the hippocampus of pilocarpine-induced epileptic mice. The modulatory effects of the H2S donor on inflammatory cytokines were prevented by glibenclamide, a common KATP channels blocker. The H2S donor promoted the expression of KATP channel subunits SUR2 and Kir6.1 in LPS-treated BV2 cells and the hippocampus of pilocarpine-induced epileptic mice. In addition, the H2S donor reduced the electroencephalography amplitude of hippocampal epileptic waves and reduced seizures in pilocarpine-induced epileptic mice, which were also attenuated by glibenclamide. These results indicated that the novel H2S donor reduced seizures and regulated microglial inflammatory cytokines by activating KATP channels, which may provide a prospective therapeutic strategy for the anti-seizure effects of H2S donor.