The Extract of Piper nigrum Improves the Cognitive Impairment and Mood in Sleep-Deprived Mice Through the JAK1/STAT3 Signalling Pathway

<i>Piper nigrum</i> L. (PN), which contains various bioactive compounds, is a plant with homologous medicine and food. Sleep deprivation (SD) profoundly impacts cognitive function and emotional health. However, the mechanisms by which PN improves cognitive function and depressive mood induced by SD remain unclear. In our study, network pharmacology and molecular docking techniques were used to predict the potential mechanisms by which PN regulates SD. In this study, 220 compounds were identified in PN, and 10 core targets were screened through network pharmacology. Animal experiments showed that PN ameliorated depressive mood and cognitive deficits in sleep-deprived mice, upregulated the serum activities of superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT), and downregulated malondialdehyde (MDA) levels. The ELISA assay showed that PN significantly decreased the tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1 beta (IL-1β) levels. Histopathological staining of brain tissue demonstrated that PN mitigates SD-induced hippocampal damage, enables the hippocampus to produce more neurotransmitters, including 5-hydroxytryptamine (5-HT), gamma-aminobutyric acid (GABA), and dopamine (DA), and reduces glutamate (Glu) levels. RT-qPCR and WB analyses further indicated that PN could exert anti-SD effects by inhibiting the over-activation of the JAK1/STAT3 signalling pathway. In the PC12 cell model, PN could reduce inflammation and prevent apoptosis, exerting neuroprotective effects. In summary, PN has positive effects on alleviating depressive symptoms and cognitive dysfunction induced by SD.