Remimazolam attenuates excessive autophagy and apoptosis in hippocampal neurons of sleep-deprived mice by suppressing endoplasmic reticulum stress through RIPK1 inhibition

Backgrounds: Sleep deprivation (SD) contributes to cognitive decline and an increased risk of dementia. Remimazolam, an ultra-short-acting benzodiazepine, has been shown to alleviate SD-induced anxiety-like behaviors. However, the underlying molecular mechanisms underlying its neuroprotective effects against SD induced injury remain poorly understood.

Methods: Following 7 days of SD, spatial learning and memory in mice were assessed using the Morris water maze and novel object recognition test. Hippocampal neuronal morphology and Apoptosis were evaluated by Nissl and TUNEL staining, respectively. In HT-22 cells, endoplasmic reticulum (ER) stress was induced by tunicamycin (TM), and cell function was evaluated by detecting cell viability, Apoptosis, Reactive Oxygen Species levels and mitochondrial membrane potential. Autophagic activity was monitored via transmission electron microscopy (TEM) and immunofluorescence, alongside evaluation of ER stress through quantification of characteristic marker proteins.

Results: The SD mice exhibited significant spatial and recognition memory deficits, accompanied by hippocampal neuronal damage characterized by morphological atrophy and irregularity. Notably, remimazolam administration effectively ameliorated both SD induced neuronal injury and cognitive impairment. Moreover, SD triggered marked upregulation of Autophagy, ER stress, and neuronal Apoptosis in hippocampal neurons, all of which were significantly suppressed by remimazolam. Activation of ER stress via ATF4 overexpression reversed the inhibitory effects of remimazolam on aberrant Autophagy and Apoptosis. In vitro, treatment with TM, significantly enhanced autophagic activation, increased autophagic flux, and promoted Apoptosis in neuronal cells. These effects were attenuated by remimazolam. Mechanistically, remimazolam suppressed AMPK signaling by downregulating RIPK1 expression, thereby inhibiting ER stress induced excessive Autophagy and Apoptosis. Importantly, RIPK1 upregulation effectively abrogated the protective effects of remimazolam both in vivo and in vitro.

Conclusion: through RIPK1 downregulation, remimazolam suppressed ER stress-triggered neuronal Autophagy and Apoptosis, ultimately ameliorating sleep deprivation-induced cognitive impairment in mice.