Sleep Deprivation Induces Dopamine System Maladaptation and Escalated Corticotrophin-Releasing Factor Signaling in Adolescent Mice

Adolescent sleep and its disruption in depression and anxiety

Adolescence is a pivotal stage during development when one's personality, emotion, and behavioral traits are shaped to a great extent, and the underlying neural circuits undergo substantial developmental organizations. Dramatic and dynamic changes occur in sleep architecture throughout the postnatal developmental course. Insufficient sleep and disruption of sleep/wake coherence are prevalent among the adolescents worldwide, and even so in young patients with neuropsychiatric conditions. Although accumulating evidence has suggested a tight association between sleep disruption and depression/anxiety, the causal relationship remains largely unclear. More importantly, most of these studies focused on adult subjects, and little is known about the role of sleep during the development of mood and behavior. Here we review recent studies investigating the acute and chronic effects of adolescent sleep disruption on depression and anxiety both in humans and rodent models with focuses on the assessment methodology and age. By discussing the findings and unsolved problems, we hope to achieve a better understanding of the relationship between sleep and mental health in adolescents and provide insights for future research.

Sleep disruptions and the pathway to psychosis: An in-depth case and literature review

Key Clinical Message

The case highlights an unusual presentation where sleep issues preceded psychotic symptoms, implying link between disrupted sleep and psychosis onset. Earlier symptoms were viewed as depression but may have signaled psychosis exacerbated by insomnia.

Abstract

Sleep disorders, prevalent yet frequently overlooked in individuals with psychotic disorders, have significant associations with the onset and severity of psychosis. Here we describe the case of a patient who first presented with insomnia, but whose condition improved with the use of risperidone and was diagnosed with first-episode psychosis. Multiple studies emphasize the critical relationship between sleep disturbances and psychosis, particularly in the lead-up to first-episode psychosis. Structural abnormalities in the brain, notably the thalamus, combined with neurotransmitter imbalances involving dopamine and acetylcholine, seem pivotal in this interrelation. The connection between dopamine, sleep disturbances, and psychosis, specifically the role of D2 dopamine receptors, highlights a potential pathway bridging sleep irregularities with psychosis. The study underscores the need for further research to delineate the relationship between sleep disturbances and psychosis and to assess the efficacy of various therapeutic interventions targeting both conditions.

Differential effects of sleep deprivation on behavior and microglia in a brain-region-specific manner in young and aged male mice

Microglia, resident immune cells in the central nervous system, constantly monitor the state of the surrounding brain activity. The animal model induced by sleep deprivation (SD) is widely used to study the pathophysiological mechanisms of insomnia and bipolar disorder. However, it remains unclear whether SD affects behaviors in young and aged male mice and microglia in various brain regions. In this study, we confirmed brain region-specific changes in microglial density and morphology in the accumbens nucleus (Acb), amygdala (AMY), cerebellum (Cb), corpus callosum (cc), caudate putamen, hippocampus (HIP), hypothalamus (HYP), medial prefrontal cortex (mPFC), and thalamus (TH) of young mice. In addition, the density of microglia in old mice was higher than that in young mice. Compared with young mice, old mice showed a markedly increased microglial size, decreased total length of microglial processes, and decreased maximum length. Importantly, we found that 48-h SD decreased microglial density and morphology in old mice, whereas SD increased microglial density and morphology in most observed brain regions in young mice. SD-induced hyperactivity was observed only in young mice but not in old mice. Moreover, microglial density (HIP, AMY, mPFC, CPu) was significantly positively correlated with behaviors in SD- and vehicle-treated young mice. Contrarily, negative correlations were shown between the microglial density (cc, Cb, TH, HYP, Acb, AMY) and behaviors in vehicle-treated young and old mice. These results suggest that SD dysregulates the homeostatic state of microglia in a region- and age-dependent manner. Microglia may be involved in regulating age-related behavioral responses to SD.

FAME4-associating YEATS2 knockdown impairs dopaminergic synaptic integrity and leads to seizure-like behaviours in Drosophila melanogaster

Familial adult myoclonus epilepsy (FAME) is a neurological disorder caused by a TTTTA/TTTCA intronic repeat expansion. FAME4 is one of the six types of FAME that results from the repeat expansion in the first intron of the gene YEATS2. Although the RNA toxicity is believed to be the primary mechanism underlying FAME, the role of genes where repeat expansions reside is still unclear, particularly in the case of YEATS2 in neurons. This study used Drosophila to explore the effects of reducing YEATS2 expression. Two pan-neuronally driven dsDNA were used for knockdown of Drosophila YEATS2 (dYEATS2), and the resulting molecular and behavioural outcomes were evaluated. Drosophila with reduced dYEATS2 expression exhibited decreased tolerance to acute stress, disturbed locomotion, abnormal social behaviour, and decreased motivated activity. Additionally, reducing dYEATS2 expression negatively affected tyrosine hydroxylase (TH) gene expression, resulting in decreased dopamine biosynthesis. Remarkably, seizure-like behaviours induced by knocking down dYEATS2 were rescued by the administration of L-DOPA. This study reveals a novel role of YEATS2 in neurons in regulating acute stress responses, locomotion, and complex behaviours, and suggests that haploinsufficiency of YEATS2 may play a role in FAME4.