Signals were amplified (20,000) and conditioned with neuroamplifiers/filters (model 15A94, Grass). disorders are highly prevalent in patients with TBI (1,2). In fact, sleep disturbances have been reported in up to 72% of patients with TBI (including mild TBI) up to 3 years after injury (3,4). TBI patients with sleep disturbances have longer inpatient hospital stays, a higher cost of rehabilitation, and a higher rate of functional disability (5,6). Moreover, sleep disruption impairs attention and memory formation and exacerbates cognitive deficits in TBI (79). Seventy-five percent of reported TBI cases are mild in nature (that is, concussion), but even concussion can have chronic neurological sequelae, including cognitive, motor, and sleep problems (10,11). Thus far, most studies on animal models of TBI have focused on either primary histological outcomes or cognitive and motor deficits in the acute setting after injury (12). To date, no animal models have rigorously described activity or sleep-wake patterns in the chronic setting after brain injury. Even more pressing, there are no proven therapies to mitigate or prevent the neurocognitive and neurobehavioral Onjisaponin B consequences of TBI (13). Therefore, there is an imminent need to better understand chronic sleep disturbances in brain injury and to identify new therapeutic options. We applied a variety of established activity and behavioral Rabbit Polyclonal to CDK7 state assays to define sleep-wake disturbances in an animal model of mild TBI using fluid percussion injury (FPI) in mice. To accomplish this, we first monitored long-term activity using a previously validated locomotor beam break assay (14). To further investigate changes in activity profiles, we next performed Onjisaponin B electroencephalography (EEG)/electromyography (EMG) recordings in freely behaving mice, which allowed assessment of nonrapid eye movement (NREM) sleep, rapid eye movement (REM) sleep, and wake states, as well as power spectral analyses. To investigate the mechanisms underlying injury-induced sleep disturbances, we initially focused on the neuropeptide orexin (also known as hypocretin), which is involved in maintaining wakefulness (15). To test the hypothesis that mild TBI causes dysfunction of the orexin system, we examined orexin neuron activation in response to a period of sustained wakefulness. We next hypothesized that dietary branched-chain amino acid (BCAA) supplementation could alleviate injury-induced deficits in wakefulness. We have previously shown that BCAAs restore network excitability in the hippocampus after mild TBI (16,17). Dietary amino acids have been shown to act directly on orexin neurons to modulate membrane excitability (18). We gave mice BCAA supplementation in the drinking water, which improved both orexin neuron activation and injury-induced sleep disturbances, indicating that BCAAs can restore wakefulness, at least in part, by activating orexinergic neurons. == RESULTS == == TBI causes subtle yet persistent alterations in activity over 30 days == A widely accepted, commonly used mouse model of mild TBI is the lateral FPI model (19,20). This experimental method provides a highly reproducible, closed head injury that recapitulates many key features of human TBI including memory deficits, gliosis, and Onjisaponin B electro-physiological perturbation (19,20). Mice were randomized to either FPI or sham surgery and subjected to extensive locomotor activity monitoring from 3 to 34 days. The experimental timeline denoting the predetermined time blocks is shown inFig. 1A, and Onjisaponin B consists of the immediate postoperative (days 0 to 4), acute (days 5 to 14), subacute (days 15 to 24), and chronic (days 25 to 34) periods after injury or sham surgery. Activity patterns were analyzed for each of the time blocks. We applied our previously established algorithm in which 40 s of continuous inactivity was shown to be highly predictive of sleep; therefore, an inactive bout was counted as sleep only when mice remained still for greater than 40 continuous seconds (14). == Fig. 1. Mild TBI decreased overall Onjisaponin B activity and fragmented.