Alteration of circadian time structure of blood pressure caused by night shift schedule.
The effects of night shift schedules on circadian time structure of blood pressure were studied in seven healthy young subjects by continuous monitoring of blood pressure every 30 min for 72 h. In the control experiment, subjects were instructed to sleep at regular times with the light off at 00.00 h and the light on at 07.00 h. In the shift experiment, they were instructed to go to bed at 06.00 h and wake up at 11.00 h. The circadian rhythm of blood pressure rapidly phase delayed by 3.5 h in the second night shift day as a group phenomenon. Individual differences in changes in power spectral patterns of blood pressure were found in the night shift schedule. Ultradian rhythmicity of blood pressure was more pronounced in three subjects, whereas the circadian rhythmicity was maintained in four subjects. These findings held when the adaptation to shift work was taken into account. (+info)
Intrapreoptic microinjection of GHRH or its antagonist alters sleep in rats.
Previous reports indicate that growth hormone-releasing hormone (GHRH) is involved in sleep regulation. The site of action mediating the nonrapid eye movement sleep (NREMS)-promoting effects of GHRH is not known, but it is independent from the pituitary. GHRH (0.001, 0. 01, and 0.1 nmol/kg) or a competitive antagonist of GHRH (0.003, 0.3, and 14 nmol/kg) was microinjected into the preoptic area, and the sleep-wake activity was recorded for 23 hr after injection in rats. GHRH elicited dose-dependent increases in the duration and in the intensity of NREMS compared with that in control records after intrapreoptic injection of physiological saline. The antagonist decreased the duration and intensity of NREMS and prolonged sleep latency. Consistent alterations in rapid eye movement sleep (REMS) and in brain temperature were not found. The GHRH antagonist also attenuated the enhancements in NREMS elicited by 3 hr of sleep deprivation. Histological verification of the injection sites showed that the majority of the effective injections were in the preoptic area and the diagonal band of Broca. The results indicate that the preoptic area mediates the sleep-promoting activity of GHRH. (+info)
Sustained antidepressant effect of sleep deprivation combined with pindolol in bipolar depression. A placebo-controlled trial.
Total sleep deprivation (TSD) shows powerful but transient clinical effects in patients affected by bipolar depression. Pindolol blocks the serotonergic 5-HT1A autoreceptor, thus improving the antidepressant effect of selective serotonin reuptake inhibitors. We evaluated the interaction of TSD and pindolol in the treatment of acute episodes of bipolar depression. Forty bipolar depressed inpatients were randomized to receive pindolol 7.5 mg/day or placebo for nine days in combination with three consecutive TSD cycles. Pindolol significantly improved the antidepressant effect of TSD, and prevented the short-term relapse after treatment. The response rate (HDRS scores < 8) at the end of treatment was 15/20 for pindolol, and 3/20 for placebo. Coadministration of pindolol and TSD resulted in a complete response, which could be sustained for six months with lithium salts alone, in 65% of cases. This results suggest a major role for serotonergic transmission in the mechanism of action of TSD, and makes TSD treatment more effective in the treatment of bipolar depression. (+info)
Simple reaction time, duration of driving and sleep deprivation in young versus old automobile drivers.
Car accidents are one of the major causes of death in modern society and sleepiness is identified as one major risk factor. The purposes of the present study were: (1) to relate the sleep loss and driving time to a performance indicator and (2) to identify risk factors of performance decrement. We investigated 294 drivers (age < 30 years, n = 100; age > or = 30 years, n = 194) who drove into a rest stop area. All were asked to fill out a questionnaire about the drive and previous sleep/wake pattern, and to carry out a 10 min, simple reaction time (RT) test. The level of performance is identified by the 10% slowest RTs. Multiple regression analysis, with the mean of the 10% Slowest RTs as the dependent variable, showed that age, duration of drive, and duration (shortness) of previous breaks were the main predictors. Our study suggests that public awareness may need to be raised with respect excessive length of driving, especially in young drivers. (+info)
Differential c-Fos expression in cholinergic, monoaminergic, and GABAergic cell groups of the pontomesencephalic tegmentum after paradoxical sleep deprivation and recovery.
Multiple lines of evidence indicate that neurons within the pontomesencephalic tegmentum are critically involved in the generation of paradoxical sleep (PS). From single-unit recording studies, evidence suggests that unidentified but "possibly" cholinergic tegmental neurons discharge at higher rates during PS than during slow wave sleep or even waking and would thus play an active role, whereas "presumed" monoaminergic neurons cease firing during PS and would thus play a permissive role in PS generation. In the present study performed on rats, c-Fos immunostaining was used as a reflection of neuronal activity and combined with immunostaining for choline acetyltransferase (ChAT), serotonin (Ser), tyrosine hydroxylase (TH), or glutamic acid decarboxylase (GAD) for immunohistochemical identification of active neurons during PS recovery ( approximately 28% of recording time) as compared with PS deprivation (0%) and PS control (approximately 15%) conditions. With PS recovery, there was a significant increase in ChAT+/c-Fos+ cells, a significant decrease in Ser+/c-Fos+ and TH+/c-Fos+ cells, and a significant increase in GAD+/c-Fos+ cells. Across conditions, the percent PS was correlated positively with tegmental cholinergic c-Fos+ cells, negatively with raphe serotonergic and locus coeruleus noradrenergic c-Fos+ cells, and positively with codistributed and neighboring GABAergic c-Fos+ cells. These results support the hypothesis that cholinergic neurons are active, whereas monoaminergic neurons are inactive during PS. They moreover indicate that GABAergic neurons are active during PS and could thus be responsible for inhibiting neighboring monoaminergic neurons that may be essential in the generation of PS. (+info)
Key role of 5-HT1B receptors in the regulation of paradoxical sleep as evidenced in 5-HT1B knock-out mice.
The involvement of 5-HT1B receptors in the regulation of vigilance states was assessed by investigating the spontaneous sleep-waking cycles and the effects of 5-HT receptor ligands on sleep in knock-out (5-HT1B-/-) mice that do not express this receptor type. Both 5-HT1B-/- and wild-type 129/Sv mice exhibited a clear-cut diurnal sleep-wakefulness rhythm, but knock-out animals were characterized by higher amounts of paradoxical sleep and lower amounts of slow-wave sleep during the light phase and by a lack of paradoxical sleep rebound after deprivation. In wild-type mice, the 5-HT1B agonists CP 94253 (1-10 mg/kg, i.p.) and RU 24969 (0.25-2.0 mg/kg, i.p.) induced a dose-dependent reduction of paradoxical sleep during the 2-6 hr after injection, whereas the 5-HT1B/1D antagonist GR 127935 (0.1-1.0 mg/kg, i.p.) enhanced paradoxical sleep. In addition, pretreatment with GR 127935, but not with the 5-HT1A antagonist WAY 100635, prevented the effects of both 5-HT1B agonists. In contrast, none of the 5-HT1B receptor ligands, at the same doses as those used in wild-type mice, had any effect on sleep in 5-HT1B-/- mutants. Finally, the 5-HT1A agonist 8-OH-DPAT (0.2-1.2 mg/kg, s.c.) induced in both strains a reduction in the amount of paradoxical sleep. Altogether, these data indicate that 5-HT1B receptors participate in the regulation of paradoxical sleep in the mouse. (+info)
Somnogenic relationships between tumor necrosis factor and interleukin-1.
Both tumor necrosis factor (TNF) and interleukin (IL)-1 are somnogenic cytokines. They also induce each other's production and both induce nuclear factor kappa B activation, which in turn enhances IL-1 and TNF transcription. We hypothesized that TNF and IL-1 could influence each other's somnogenic actions. To test this hypothesis, we determined the effects of blocking both endogenous TNF and IL-1 on spontaneous sleep and on sleep rebound after sleep deprivation in rabbits. Furthermore, the effects of inhibition of TNF on IL-1-induced sleep and the effects of blocking IL-1 on TNF-induced sleep were determined. A TNF receptor fragment (TNFRF), as a TNF inhibitor, and an IL-1 receptor fragment (IL-1RF), as an IL-1 inhibitor, were used. Intracerebroventricular injection of a combination of the TNFRF plus the IL-1RF significantly reduced spontaneous non-rapid eye movement sleep by 87 min over a 22-h recording period. Pretreatment of rabbits with the combination of TNFRF and IL-1RF also significantly attenuated sleep rebound after sleep deprivation. Furthermore, the TNFRF significantly attenuated IL-1-induced sleep but not fever. Finally, the IL-1RF blocked TNF-induced sleep responses but not fever. Results indicate that TNF and IL-1 cooperate to regulate physiological sleep. (+info)
Nuclear factor-kappaB-like activity increases in murine cerebral cortex after sleep deprivation.
Several well-defined sleep regulatory substances, e.g., interleukin-1beta, activate the heterodimeric transcription factor nuclear factor-kappaB (NF-kappaB). Several substances that inhibit sleep, e.g., interleukin-4, inhibit NF-kappaB activation. NF-kappaB activation promotes production of several additional substances thought to be involved in sleep regulation, e.g., nitric oxide. We investigated, therefore, whether there are diurnal rhythms of NF-kappaB activation in brain and changes in the activation after sleep deprivation. Mice were kept on a 12:12-h light-dark cycle. In one experiment, groups of mice were killed every 3 h across the 24-h cycle. In another experiment, mice were killed at 1500 after 6 h of sleep deprivation, and a group of control mice were killed at the same time. Nuclear proteins were extracted from each brain tissue sample, and NF-kappaB-like activity was determined with an electrophoretic mobility shift assay. In cerebral cortex, but not other areas of brain, there was a diurnal rhythm in NF-kappaB-like activation; highest levels were found during the light period. NF-kappaB-like activation was higher in cerebral cortex after sleep deprivation compared with values obtained from control mice. The results are consistent with the hypothesis that sleep regulation involves multiple gene events, some of which include enhanced production of sleep regulatory substances, the actions of which involve NF-kappaB activation. (+info)