Temporal dynamics of pro-inflammatory cytokines and serum corticosterone following acute sleep fragmentation in male mice

Edaravone Attenuates Sleep Deprivation-Induced Memory Deficits by Inhibiting Oxidative Stress and Neuroinflammation in Murine Models

Background: Sleep deprivation (SD) is a common condition affecting many people in modern life. Edaravone (Eda) is a neuroprotective drug, but whether it can improve cognitive impairment caused by SD remains unclear. Methods: Animals received oral gavage doses of Eda (10, 20, and 40 mg/kg) for 8 and 5 days before and during SD. Starting from the 6th day, a modified multiple platform model was used to produce SD in mice for 72 h. The Lashley III maze was used for evaluating spatial learning and memory. Malondialdehyde (MDA) in the hippocampus and serum corticosterone were assessed. Total antioxidant capacity (TAC) and the activity of the enzymes glutathione peroxidase (GPx) and superoxide dismutase (SOD) were measured. Growth-associated protein 43 (GAP-43), synapsin 1 (SYN-1), post-synaptic density-95 (PSD-95), synaptophysin (SYP), and signs of inflammation were detected using Western blotting. Results: SD caused cognitive impairment, whereas Eda pretreatment warded off such an effect. While serum corticosterone levels rose with SD as well, they decreased in SD mice that received Eda (p < 0.05). Moreover, Eda normalized the SD-induced decline in hippocampal activity of SOD and GPx, lowered MDA levels, and elevated TAC (p < 0.01). Additionally, the hippocampal levels of GAP-34, SYP, SYN-I, and PSD-95 were elevated, while IL-1β and tumor necrosis factor α (TNF-α) were lowered following Eda pretreatment (p < 0.05). Conclusions: SD caused memory impairment; however, pretreatment with Eda improved memory by upregulating synaptic proteins in the hippocampus and having anti-inflammatory and antioxidant effects.

Effect of glucocorticoid blockade on inflammatory responses to acute sleep fragmentation in male mice

The association between sleep and the immune-endocrine system is well recognized, but the nature of that relationship is not well understood. Sleep fragmentation induces a pro-inflammatory response in peripheral tissues and brain, but it also activates the hypothalamic-pituitary-adrenal (HPA) axis, releasing glucocorticoids (GCs) (cortisol in humans and corticosterone in mice). It is unclear whether this rapid release of glucocorticoids acts to potentiate or dampen the inflammatory response in the short term. The purpose of this study was to determine whether blocking or suppressing glucocorticoid activity will affect the inflammatory response from acute sleep fragmentation (ASF). Male C57BL/6J mice were injected i.p. with either 0.9% NaCl (vehicle 1), metyrapone (a glucocorticoid synthesis inhibitor, dissolved in vehicle 1), 2% ethanol in polyethylene glycol (vehicle 2), or mifepristone (a glucocorticoid receptor antagonist, dissolved in vehicle 2) 10 min before the start of ASF or no sleep fragmentation (NSF). After 24 h, samples were collected from brain (prefrontal cortex, hypothalamus, hippocampus) and periphery (liver, spleen, heart, and epididymal white adipose tissue (EWAT)). Proinflammatory gene expression (TNF-α and IL-1β) was measured, followed by gene expression analysis. Metyrapone treatment affected pro-inflammatory cytokine gene expression during ASF in some peripheral tissues, but not in the brain. More specifically, metyrapone treatment suppressed IL-1β expression in EWAT during ASF, which implies a pro-inflammatory effect of GCs. However, in cardiac tissue, metyrapone treatment increased TNF-α expression in ASF mice, suggesting an anti-inflammatory effect of GCs. Mifepristone treatment yielded more significant results than metyrapone, reducing TNF-α expression in liver (only NSF mice) and cardiac tissue during ASF, indicating a pro-inflammatory role. Conversely, in the spleen of ASF-mice, mifepristone increased pro-inflammatory cytokines (TNF-α and IL-1β), demonstrating an anti-inflammatory role. Furthermore, irrespective of sleep fragmentation, mifepristone increased pro-inflammatory cytokine gene expression in heart (IL-1β), pre-frontal cortex (IL-1β), and hypothalamus (IL-1β). The results provide mixed evidence for pro- and anti-inflammatory functions of corticosterone to regulate inflammatory responses to acute sleep loss.