Dose response of acute cocaine on sleep/waking behavior in mice

Metabotropic glutamate receptor function and regulation of sleep-wake cycles

Metabotropic glutamate (mGlu) receptors are the most abundant family of G-protein coupled receptors and are widely expressed throughout the central nervous system (CNS). Alterations in glutamate homeostasis, including dysregulations in mGlu receptor function, have been indicated as key contributors to multiple CNS disorders. Fluctuations in mGlu receptor expression and function also occur across diurnal sleep-wake cycles. Sleep disturbances including insomnia are frequently comorbid with neuropsychiatric, neurodevelopmental, and neurodegenerative conditions. These often precede behavioral symptoms and/or correlate with symptom severity and relapse. Chronic sleep disturbances may also be a consequence of primary symptom progression and can exacerbate neurodegeneration in disorders including Alzheimer's disease (AD). Thus, there is a bidirectional relationship between sleep disturbances and CNS disorders; disrupted sleep may serve as both a cause and a consequence of the disorder. Importantly, comorbid sleep disturbances are rarely a direct target of primary pharmacological treatments for neuropsychiatric disorders even though improving sleep can positively impact other symptom clusters. This chapter details known roles of mGlu receptor subtypes in both sleep-wake regulation and CNS disorders focusing on schizophrenia, major depressive disorder, post-traumatic stress disorder, AD, and substance use disorder (cocaine and opioid). In this chapter, preclinical electrophysiological, genetic, and pharmacological studies are described, and, when possible, human genetic, imaging, and post-mortem studies are also discussed. In addition to reviewing the important relationships between sleep, mGlu receptors, and CNS disorders, this chapter highlights the development of selective mGlu receptor ligands that hold promise for improving both primary symptoms and sleep disturbances.

Arousal-Mediated Sleep Disturbance Persists During Cocaine Abstinence in Male Mice

Acute cocaine disturbs sleep on a dose-dependent basis; however, the consequences of chronic cocaine remain unclear. While the arousal promotion following cocaine has been well-established, effects of cocaine on sleep after termination of chronic cocaine exposure appear variable in human subjects with few studies in non-human subjects. Here, a within-subjects design (outcomes normalized to baseline, undisturbed behavior) and between-subjects design (repeated experimenter-administered cocaine vs. experimenter-administered saline) was used to investigate sleep homeostasis and sleep/waking under repeated cocaine/saline exposure and prolonged forced abstinence conditions in mice. Overall, during the forced abstinence period increases in arousal, as determined by sleep latency and gamma energy, persisted for 2 weeks. However, the sleep response to externally enforced sleep deprivation was unchanged suggesting that sleep disruptions during the forced abstinence period were driven by enhancement of arousal in the absence of changes in sleep homeostatic responses.

Interaction between cocaine use and sleep behavior: A comprehensive review of cocaine's disrupting influence on sleep behavior and sleep disruptions influence on reward seeking

Dopamine, orexin (hypocretin), and adenosine systems have dual roles in reward and sleep/arousal suggesting possible mechanisms whereby drugs of abuse may influence both reward and sleep/arousal. While considerable variability exists across studies, drugs of abuse such as cocaine induce an acute sleep loss followed by an immediate recovery pattern that is consistent with a normal response to loss of sleep. Under more chronic cocaine exposure conditions, an abnormal recovery pattern is expressed that includes a retention of sleep disturbance under withdrawal and into abstinence conditions. Conversely, experimentally induced sleep disturbance can increase cocaine seeking. Thus, complementary, sleep-related therapeutic approaches may deserve further consideration along with development of non-human models to better characterize sleep disturbance-reward seeking interactions across drug experience.

Sleep Deprivation Enhances Cocaine Conditioned Place Preference in an Orexin Receptor-Modulated Manner

Drug addiction and withdrawal are characterized by sleep disruption, but the effects of sleep disruption on these states are not well characterized. Sleep deprivation (SD) immediately before the cocaine conditioning trials enhanced cocaine conditioned place preference (CPP) in a dose-dependent manner (3, 8 mg/kg but not 15 mg/kg) in mice. SD immediately before the postconditioning test also enhanced cocaine CPP preference in a dose-dependent manner (8 mg/kg, but not 3, 15 mg/kg). Exposure to orexin-receptor antagonism (1 mg/kg SB 334867, an orexin 1 receptor antagonist; OX1R) just before cocaine-conditioning trials or the postconditioning test attenuated SD-enhanced preference. This suggests a potential therapeutic role for the manipulation of the orexin system to mitigate drug seeking, especially in the context of sleep loss before drug exposure.

Sleep deprivation alters the time course but not magnitude of locomotor sensitization to cocaine

Repeated exposure to drugs of abuse progressively increases the response to the same stimuli, a process known as sensitization. Behavioral sensitization to cocaine administration is often measured in non-human subjects via locomotor activity which is easily quantifiable. The effects of four hours of sleep deprivation on repeated cocaine (five daily and one challenge) showed attenuated hyperactivity on the first day only, compared to the non-deprived group. Both groups reached the same final level of sensitization, indicating that sleep deprivation altered the time course, but not magnitude of locomotor sensitization.