Around-the-clock noise exposure induces hippocampus apoptosis and subsequent cognitive impairment via the PI3K/SGK1/Foxo3 signaling pathway

Noise exposure is an environmental stressor associated with cognitive impairment. Workers in specific work environments are often exposed to around-the-clock noise and experience severe emotional and cognitive dysfunctions associated with neuropathology similar to Alzheimer's disease. However, the underlying neural mechanisms have not been extensively investigated. The molecular pathways underlying cognitive impairment following around-the-clock noise exposure were evaluated using male Wistar rats. The open-field and Morris water maze tests were used to assess cognitive performance. RNA sequencing was employed to identify key regulators and pathological pathways of cognitive impairment. Histological changes were observed using hematoxylin and eosin staining, Nissl staining, transmission electron microscopy, and immunofluorescence. Western blotting was performed to detect altered apoptotic markers. Around-the-clock noise exposure significantly induced cognitive decline and neuronal damage in rat. Transcriptome sequencing of hippocampal tissues from control and noise-exposed rats revealed that the expression of the serum/glucocorticoid regulated kinase 1 (SGK1) gene was reduced, with a corresponding decrease in its protein levels. Moreover, this dysregulation led to the inhibition of the intracellular PI3K/SGK1/Foxo3 pathway, triggering the upregulation of the apoptotic proteins Bcl-2, Bax, Fasl, and TRAIL. These findings suggest that around-the-clock noise exposure induces hippocampal neuronal apoptosis, thus exacerbating cognitive impairment. This elucidates the potential role of the PI3K/SGK1/Foxo3 pathway in noise-induced neuronal damage.