GDF11 Mediates The Antagonistic Effect Of Hydrogen Sulfide On Chronic Stress-induced Cognitive Dysfunction By Inhibition Of Hippocampal Pyroptosis

[Background and Objective]Hydrogen sulfide（H₂S）,as a novel neuroregulatory factor,ameliorates cognitive impairment induced by chronic stress,but the mechanisms are not clear.Previous research has demonstrated that growth differentiation factor-11（GDF11）alleviates the deficiency of learning and memory function and that inhibition of hippocampal pyroptosis contributes to improvement of cognitive function.The purpose of this paper is to explore whether GDF11 mediates the antagonistic effect of H₂S on chronic stress-induced cognitive dysfunction via inhibiting hippocampal pyroptosis.[Methods]1.Adeno-associated virus 9-mediated small RNA interference of GDF11（AAV9-GDF11-si RNA）and adeno-associated virus 9-mediated expression of GDF11（AAV9-GDF11）were constructed and synthetized.2.The chronic unpredictable mild stress（CUMS）was used as the model of chronic stress.3.The cognitive ability was detected by the Y-maze and novel object recognition（NOR）tests.4.The expressions of hippocampal GDF11 and pyroptosis-associatedproteins[NLRP3,pro-Caspase-1,cleaved-Caspase-1,gasdermin D（GSDMD）and gasdermin D-N domain（GSDMD-N）]were measured by western blotting.5.The contents of hippocampal interleukin-1β（IL-1β）and interleukin-18（IL-18）were detected by enzyme-linked immuno sorbent assay（ELISA）.[Results]1.AAV9-GDF11-si RNA silenced GDF11 expression in the hippocampal tissue.Hippocampal stereotactic injection of AAV9-GDF11-si RNA markedly reduced the protein expression of GDF11 in the hippocampus.2.Silencing hippocampal GDF11 abolished H₂S-improved cognitive function in chronic stress-exposed rats.In Y-maze test,Na HS increased the spontaneous alternation rate in CUMS-exposed rats,while AAV9-GDF11-si RNA markedly decreased the spontaneous alternation rate in the rats cotreated with CUMS and Na HS.In NOR test,Na HS augmented the index of discrimination in CUMS-exposed rats,but AAV9-GDF11-si RNA reduced the index of discrimination in the rats cotreated with CUMS and Na HS.These results suggested that silencing hippocampal GDF11 abolishes H₂S-enhanced cognitive function in chronic stress-exposed rats.3.Silencing hippocampal GDF11 abolished the antagonistic effect of H₂S on hippocampal pyroptosis in chronic stress-exposed rats.In the hippocampus of CUMS-exposed rats,Na HS down-regulated the expressions of NLRP3,cleaved-Caspase-1,and GSDMD-N,decreased the contents of IL-1βand IL-18,as well as up-regulated the expression of GSDMD.Nevertheless,AAV9-GDF11-si RNA abolished Na HS-induced the down-regulation of NLRP3,cleaved-Caspase-1 and GSDMD-N expressions,the decreases in IL-1βand IL-18 contents,as well as the up-regulation of GSDMD expression in the hippocampus of CUMS-exposed rats.These results suggested that silencing hippocampal GDF11 abolishes the antagonistic effect of H₂S on hippocampal pyroptosis in chronic stress-exposed rats.4.AAV9-GDF11 over-expressed GDF11 in the hippocampal tissue.Hippocampal stereotactic injection of AAV9-GDF11 significantly increased the protein expression of GDF11 in the hippocampus.5.Over-expressing hippocampal GDF11 improved cognitive function in chronic stress-exposed rats.In the CUMS-exposed rats,AAV9-GDF11 significantly augmented spontaneous alternation rate in Y-maze test and the index of discrimination in NOR test.These results indicated that over-expressing hippocampal GDF11 promoted cognitive function in chronic stress-exposed rats.6.Over-expressing hippocampal GDF11 antagonized hippocampal pyroptosis in chronic stress-exposed rats.In the hippocampus of CUMS-exposed rats,AAV9-GDF11 reduced the expressions of NLRP3,cleaved-Caspase-1,and GSDMD-N,decreased the contents of IL-1βand IL-18,as well as increased the expression of GSDMD,which suggested that over-expressing hippocampal GDF11 mitigates hippocampal pyroptosis in chronic stress-exposed rats.[Conclusion]GDF11 mediates the antagonistic effect of H₂S on chronic stress-induced cognitive dysfunction by inhibition of hippocampal pyroptosis.