Assessment of sleep in mice currently requires initial implantation of chronic electrodes for assessment of electroencephalogram (EEG) and electromyogram (EMG) followed by time to recover from surgery. Hence, it is not ideal for high-throughput screening. To address this deficiency, a method of assessment of sleep and wakefulness in mice has been developed based on assessment of activity/inactivity either by digital video analysis or by breaking infrared beams in the mouse cage. It is based on the algorithm that any episode of continuous inactivity of > or =40 s is predicted to be sleep. The method gives excellent agreement in C57BL/6J male mice with simultaneous assessment of sleep by EEG/EMG recording. The average agreement over 8,640 10-s epochs in 24 h is 92% (n = 7 mice) with agreement in individual mice being 88-94%. Average EEG/EMG determined sleep per 2-h interval across the day was 59.4 min. The estimated mean difference (bias) per 2-h interval between inactivity-defined sleep and EEG/EMG-defined sleep was only 1.0 min (95% confidence interval for mean bias -0.06 to +2.6 min). The standard deviation of differences (precision) was 7.5 min per 2-h interval with 95% limits of agreement ranging from -13.7 to +15.7 min. Although bias significantly varied by time of day (P = 0.0007), the magnitude of time-of-day differences was not large (average bias during lights on and lights off was +5.0 and -3.0 min per 2-h interval, respectively). This method has applications in chemical mutagenesis and for studies of molecular changes in brain with sleep/wakefulness.

BackgroundBy altering specific developmental signaling pathways that are necessary for fetal lung development, perinatal nicotine exposure affects lung growth and differentiation, resulting in the offsprings' predisposition to childhood asthma; peroxisome proliferator-activated receptor gamma (PPARγ) agonists can inhibit this effect. However, whether the perinatal nicotine-induced asthma risk is restricted to nicotine-exposed offspring only; whether it can be transmitted to the next generation; and whether PPARγ agonists would have any effect on this process are not known.MethodsTime-mated Sprague Dawley rat dams received either placebo or nicotine (1 mg/kg, s.c.), once daily from day 6 of gestation to postnatal day (PND) 21. Following delivery, at PND21, generation 1 (F1) pups were either subjected to pulmonary function tests, or killed to obtain their lungs, tracheas, and gonads to determine the relevant protein markers (mesenchymal contractile proteins), global DNA methylation, histone 3 and 4 acetylation, and for tracheal tension studies. Some F1 animals were used as breeders to generate F2 pups, but without any exposure to nicotine in the F1 pregnancy. At PND21, F2 pups underwent studies similar to those performed on F1 pups.ResultsConsistent with the asthma phenotype, nicotine affected lung function in both male and female F1 and F2 offspring (maximal 250% increase in total respiratory system resistance, and 84% maximal decrease in dynamic compliance following methacholine challenge; P < 0.01, nicotine versus control; P < 0.05, males versus females; and P > 0.05, F1 versus F2), but only affected tracheal constriction in males (51% maximal increase in tracheal constriction following acetylcholine challenge, P < 0.01, nicotine versus control; P < 0.0001, males versus females; P > 0.05, F1 versus F2); nicotine also increased the contractile protein content of whole lung (180% increase in fibronectin protein levels, P < 0.01, nicotine versus control, and P < 0.05, males versus females) and isolated lung fibroblasts (for example, 45% increase in fibronectin protein levels, P < 0.05, nicotine versus control), along with decreased PPARγ expression (30% decrease, P < 0.05, nicotine versus control), but only affected contractile proteins in the male trachea (P < 0.05, nicotine versus control, and P < 0.0001, males versus females). All of the nicotine-induced changes in the lung and gonad DNA methylation and histone 3 and 4 acetylation were normalized by the PPARγ agonist rosiglitazone except for the histone 4 acetylation in the lung.ConclusionsGermline epigenetic marks imposed by exposure to nicotine during pregnancy can become permanently programmed and transferred through the germline to subsequent generations, a ground-breaking finding that shifts the current asthma paradigm, opening up many new avenues to explore.

Sleep disorders are highly prevalent in patients with traumatic brain injury (TBI) and can significantly impair cognitive rehabilitation. No proven therapies exist to mitigate the neurocognitive consequences of TBI. We show that mild brain injury in mice causes a persistent inability to maintain wakefulness and decreases orexin neuron activation during wakefulness. We gave mice a dietary supplement of branched-chain amino acids (BCAAs), precursors for de novo glutamate synthesis in the brain. BCAA therapy reinstated activation of orexin neurons and improved wake deficits in mice with mild brain injury. Our data suggest that dietary BCAA intervention, acting in part through orexin, can ameliorate injury-induced sleep disturbances and may facilitate cognitive rehabilitation after brain injury.