Melatonin alleviates cognitive impairment via modulating NLRP3/Caspase 1 pathway in db/db mice.

Abstract

BackgroundActivation of NLRP3 inflammasome has been implicated in cognitive impairment. Melatonin, known for its anti-inflammatory properties and traditional use in regulating circadian rhythms, is the focus of this study. This study intended to investigate the role of melatonin in diabetic cognitive impairment model.ObjectiveThe present study aimed to investigate the underlying mechanism of melatonin in alleviating diabetic cognitive impairment by suppressing NLRP3/Caspase 1 signaling pathway.MethodsCognitive function was assessed using Morris water maze test and Novel Object Recognition test. Apoptosis rate of hippocampal neurons was evaluated by TUNEL staining. Western blot was used to evaluate NLRP3/Caspase 1 pathway expression. Double immunofluorescence labelling of GFAP, Iba-1 or NeuN with NLRP3 respectively showed the localization of NLRP3 in hippocampus of db/db mice. In vitro, HT-22 cells treated with high glucose as cellular model were transfected with pc-DNA3.1-mNLRP3 or co-cultured with NLRP3 inhibitor MCC950 to elucidate NLRP3/Caspase 1 pathway in neuronal apoptosis regulation.ResultsMelatonin treatment improved cognitive function and morphologic abnormalities of hippocampal neurons. The double immunofluorescence labelling revealed melatonin inhibited NLRP3 inflammasome activation in hippocampal neurons rather than microglia or astrocytes. TUNEL staining and western blot showed melatonin markedly reversed the upregulation of NLRP3/Caspase 1 signaling pathway against neuronal apoptosis.ConclusionsMelatonin attenuates diabetic cognitive impairment in db/db mice with down-regulation of NLRP3/Caspase 1 signaling pathway. In vivo and vitro studies supported that NLRP3 activation in hippocampal neurons was associated with diabetic cognitive impairment progression.