Nicotine-prevented learning and memory impairment in REM sleep-deprived rat is modulated by DREAM protein in the hippocampus

Chronic caffeine consumption improves the acute REM sleep deprivation-induced spatial memory impairment while altering NMDA receptor subunit expression in male rats

Caffeine is a psychostimulant substance that is mostly used to prevent fatigue, increase alertness, and ameliorate sleep loss situations. In this study, we aimed to investigate the effect of chronic caffeine consumption on learning and memory functions and related genes in REM (rapid-eye-movement) sleep-deprived rats. During the neonatal period [postnatal day (PND) 28] Wistar albino male rats (n=32) were randomly assigned into four groups: control (C), caffeine application (Cf), acute REM sleep-deprivation (RD), and caffeine application+acute RD (Cf+RD). The 48 hours of RD was executed when caffeine administration was completed. The learning and memory performance was evaluated by the Morris Water Maze Test (MWMT). Following this, the rats were decapitated to isolate hippocampus tissues. In MWMT, time spent in the targeted quadrant decreased significantly in the RD group compared to the C and Cf+RD group. NR2A expression level increased in the RD group compared to C, Cf, and Cf+RD groups (p<0.05). NR2B expression level increased in RD and Cf +RD groups compared to C and Cf groups (p<0.05). BDNF and c-Fos expression levels did not differ significantly between the groups. RD impaired hippocampal spatial memory performance in the MWMT test. Our results indicated that chronic caffeine consumption has a therapeutic effect on spatial memory deterioration impairment caused by RD. Furthermore, it seems that the effect of caffeine RD on the hippocampus may be mediated by NR2A.

Mild regular treadmill exercise ameliorated the detrimental effects of acute sleep deprivation on spatial memory

Vulnerable areas like the hippocampus are sensitive to insults such as sleep deprivation (SD); they are also susceptible to environmental enrichment. Much evidence is accumulating that chronic sleep deprivation causes alterations in the hippocampus that responsible for spatial memory. However, there is conflicting about the differences between acute and chronic SD results. The purpose of this study was to determine the protective effects of mild treadmill exercise on acute SD rats. Four groups were created as control, exercise, sleep deprivation, exercise + sleep deprivation. Multiple platforms method was used to induce REM sleep deprivation (RD) for 48 h. The exercise was applied fivedaysperweekforfour weeks(5 × 4). For the first and second weeks, the length of the exercise was 15 min in two sessions (5 min interval) followed by 15 min in three, 15 min in four sessions. Morris water maze (MWM) was used as a spatial memory test. Gene level was determined by using the qPCR technique. Malondialdehyde (MDA) content in the hippocampus was measured as an extent of peroxidative damage to lipids by using the ELISA method. 48 h RD impaired long-term spatial memory significantly. Mild, regular treadmill exercise ameliorated the detrimental effects of acute sleep deprivation on memory. There was no significant difference in MDA between groups. Hippocampal gene expression did not show any changes in all groups. Lack of correlation between memory impairment and levels of genes in the hippocampus is likely to be related to the differences in behavioral and genetic mechanisms.

Assessing the effect of nicotine dose in cigarette smoking on sleep quality

BACKGROUND

While several studies assessed the relation between cigarette smoking and sleep, there are still very few studies assessing the effect of nicotine in cigarette smoking on sleep.

AIM

This study aimed to compare higher vs lower nicotine levels in cigarette smoking on sleep quality.

METHODS

We used data from the recently released dataset for the Randomized Trial of Reduced-Nicotine Standards for Cigarettes. We included three groups in the current study: the least nicotine concentration (i.e., 0.4 mg/g), a moderate nicotine concentration (i.e., 5.2 mg/g), and the highest nicotine concentration (i.e., 15.8 mg/g). For each participant, we included data regarding baseline and the last follow up at 6 weeks, where we compared insomnia, sleep problems, and awakening at night, in addition to different depression and affect scores.

RESULTS

A total of 360 patients were included in this study, with a mean age of 42.4 (±13.4) years. For the three nicotine groups (i.e., 0.4 mg/g, 5.2 mg/g, and 15.8 mg/g), we included 119 (33%), 122 (34%), and 119 (33%) participants. Among the high-nicotine-dose group, the number of participants who had worsened sleep was significantly higher than the number of those who had improved sleep (p = 0.01) after 6 weeks of consumption, where 37 (31%) had worsened sleep score after 6 weeks while only 19 (16%) had improved score compared with baseline.

CONCLUSION

While previous studies established a relation either between cigarette smoking and sleep or between nicotine patches and sleep, the present study is the first to establish that higher nicotine doses in cigarettes were associated with more sleep disturbances.

The neuroprotective effect of osthole against chronic sleep deprivation (CSD)-induced memory impairment in rats

AIM

Sleep deprivation (SD) is a frequent health problem in modern society. Osthole (Ost), a natural coumarin, has antioxidant and neuroprotective properties. This study examined the functions of Ost in chronic sleep deprivation (CSD)-induced memory deficits in rats.

MAIN METHODS

The CSD rat model was constructed by applying Sleep Interruption Apparatus (SIA). The protective effect of Ost on memory ability of CSD rats was evaluated through behavioral tests. Modafinil (MOD) was a positive control for investigating the mechanisms underlying the actions of Ost. The oxidative stress changes in the cortex and hippocampus of the rats, histological changes in CA1 region in the hippocampus and the protein expressions of neural plasticity markers were measured. The hippocampal neurons were isolated from rats for evaluating the neuroprotective effects of Ost on glutamate-induced neuron injury in vitro.

KEY FINDINGS

Ost administration significantly enhanced the cognitive performance of CSD rats in the open field test, object location recognition experiment, novel object recognition experiment, and Morris water maze test. Ost could effectively normalize the levels/activities of the antioxidant enzyme system in the cortex and hippocampus. Moreover, Ost administration reversed CSD-induced abnormal state of CA1 neurocytes and the down-regulated expressions of plasticity-related genes in vivo and in vitro. Additionally, Ost also notably up-regulated the expressions of Nrf2 and HO-1 previously down-regulated in CA1 neurocytes of CSD rats and in vitro.

SIGNIFICANCE

Our findings showed that Ost alleviated CSD-induced cognitive deficits, and the activation of the Nrf2/HO-1 pathway might be involved in the neuroprotective action of Ost.

Lipid peroxidation in the descending thoracic aorta of rats deprived of REM sleep using the inverted flowerpot technique

NEW FINDINGS

What is the central question of this study? Deprivation of rapid eye movement (REM) sleep is associated with increased oxidative stress, but its effects on the blood vessels are poorly documented. We investigated whether REM sleep deprivation induces oxidative stress and causes lipid peroxidation in the aorta. What is the main finding and its important? We demonstrate that REM sleep deprivation induces oxidative stress and mediates lipid peroxidation in the aorta. This can cause endothelial changes and increased blood pressure. These findings will contribute to the growing body of literature on the mechanism underlying the effects of sleep deprivation on cardiovascular disease.

ABSTRACT

Oxidative stress-mediated lipid peroxidation is a known cause of endothelial injury or dysfunction. Deprivation of rapid eye movement (REM) sleep is associated with oxidative stress. To date, the pathogenesis of increased blood pressure after sleep deprivation remains poorly understood, particularly in the REM sleep phase. Our aim was to investigate the effects of REM sleep deprivation on blood vessels in the REM sleep-deprived rat model. Twenty-eight male Sprague-Dawley rats were divided into four equal groups: free-moving control rats, rats deprived of REM sleep for 72 h (REMsd), tank control rats and 72 h sleep-recovered rats after 72 h of REM sleep deprivation. The rats were deprived of REM sleep using the inverted flowerpot technique. Food consumption, body weight gain and systolic blood pressure were monitored. At the end of the experiment, the descending thoracic aorta was isolated for the measurement of oxidative stress markers. Despite a significant increase in food consumption in the REMsd group compared with the other groups, there was a significant reduction in body weight gain. Systolic blood pressure also showed a significant increase in the REMsd group compared with the other groups. Superoxide dismutase activity was significantly lower and malondialdehyde concentrations significantly higher in the REMsd group compared with the other groups. Increased levels of malondialdehyde are suggestive of lipid peroxidation in the blood vessels, and oxidative stress may be attributed to the initiation of the process. The changes after REM sleep deprivation revert during sleep recovery. In conclusion, the findings of the present study provide convincing evidence that REM sleep deprivation induced lipid peroxidation, leading to endothelial damage.

Cadmium association with DREAM promotes DREAM interactions with intracellular partners in a similar manner to its physiological ligand, calcium

Cd²⁺exposure has been associated with neurodegenerative diseases and other pathologies, but the underlying mechanism through which it exerts toxic effects remain unresolved.

Nicotine-prevented learning and memory impairment in REM sleep-deprived rat is modulated by DREAM protein in the hippocampus

INTRODUCTION

REM sleep deprivation is associated with impairment in learning and memory, and nicotine treatment has been shown to attenuate this effect. Recent studies have demonstrated the importance of DREAM protein in learning and memory processes. This study investigates the association of DREAM protein in REM sleep-deprived rats hippocampus upon nicotine treatment.

METHODS

Male Sprague Dawley rats were subjected to normal condition, REM sleep deprivation and control wide platform condition for 72 hr. During this procedure, saline or nicotine (1 mg/kg) was given subcutaneously twice a day. Then, Morris water maze (MWM) test was used to assess learning and memory performance of the rats. The rats were sacrificed and the brain was harvested for immunohistochemistry and Western blot analysis.

RESULTS

MWM test found that REM sleep deprivation significantly impaired learning and memory performance without defect in locomotor function associated with a significant increase in hippocampus DREAM protein expression in CA1, CA2, CA3, and DG regions and the mean relative level of DREAM protein compared to other experimental groups. Treatment with acute nicotine significantly prevented these effects and decreased expression of DREAM protein in all the hippocampus regions but only slightly reduce the mean relative level of DREAM protein.

CONCLUSION

This study suggests that changes in DREAM protein expression in CA1, CA2, CA3, and DG regions of rat's hippocampus and mean relative level of DREAM protein may involve in the mechanism of nicotine treatment-prevented REM sleep deprivation-induced learning and memory impairment in rats.