Chronic sleep deprivation induces depression- and Alzheimer’s disease-like changes in adult and ageing wild-type and Fat-1 transgenic mice

Background

Sleep disorders show comorbidity with depression and Alzheimer's disease (AD), especially in ageing. However, the neuroimmunological role of sleep deprivation (SD) as possible inducer to these conditions remains unknown. Omega-3 fatty acids (n-3 FAs) can improve depression and AD through anti-inflammation, up-regulating neurotrophins and normalizing neurotransmitters, while their therapeutic effects on sleep deprivation (SD)-induced changes in different ages requires investigation.

Methods

Adult and old Fat-1 (converting n-6 to n-3 FAs) and wild-type (WT) mice were subjected to chronic SD. After behavioral evaluation, brain FAs, monoamine neurotransmitters, circadian-gene expression, TLR-4 signaling-pathway, glial polarization, cytokine profile, and AD-related markers were analyzed using GC–MS, HPLC, qPCR, ELISA and western-blotting. Furthermore, bioinformatic analysis evaluated SD-related networking with depression and AD.

Results

SD induced anxiety, anhedonia, despair, and memory impairments. The n-3:n-6 ratio, BMAL-1 gene expression, and melatonin concentration were decreased, whereas corticosterone, TLR-4, GSK3β, and NFκB concentrations increased in SD groups compared to the controls. Increased IBA-1 protein expression and proinflammatory IL-1β, TNF-α, and IL-6 concentrations were associated with decreased monoamine neuro-transmitter levels in SD groups. APP, BACE-1, RAGE and APPβ concentrations were increased, whereas LRP-1 and APPα concentrations and the APPα/APPβ ratio were decreased in SD groups than controls. These changes were more pronounced in old WT and Fat-1 animals than adults. However, compared to WT-SD, these changes were significantly ameliorated in Fat-1-SD mice, but recovery was less pronounced in old Fat-1.

Conclusion

SD-induced neuroinflammation and impaired APP processing may contribute to behavioral impairments, which exacerbated with age. Although n-3 FAs significantly ameliorated SD-induced adverse behavioral and neuroimmunological changes, this therapeutic effect was markedly reduced in old animals.