DSIP--a tool for investigating the sleep onset mechanism: a review

Delta Sleep-Inducing Peptide Recovers Motor Function in SD Rats after Focal Stroke

Background and Objectives: Mutual effect of the preliminary and therapeutic intranasal treatment of SD rats with DSIP (8 days) on the outcome of focal stroke, induced with intraluminal middle cerebral occlusion (MCAO), was investigated. Materials and Methods: The groups were the following: MCAO + vehicle, MCAO + DSIP, and SHAM-operated. DSIP or vehicle was applied nasally 60 (±15) minutes prior to the occlusion and for 7 days after reperfusion at dose 120 µg/kg. The battery of behavioral tests was performed on 1, 3, 7, 14, and 21 days after MCAO. Motor coordination and balance and bilateral asymmetry were tested. At the end of the study, animals were euthanized, and their brains were perfused, serial cryoslices were made, and infarction volume in them was calculated. Results: Although brain infarction in DSIP-treated animals was smaller than in vehicle-treated animals, the difference was not significant. However, motor performance in the rotarod test significantly recovered in DSIP-treated animals. Conclusions: Intranasal administration of DSIP in the course of 8 days leads to accelerated recovery of motor functions.

The Blood-Brain Barrier: Regulatory Roles in Wakefulness and Sleep

Sleep and its disorders are known to affect the functions of essential organs and systems in the body. However, very little is known about how the blood-brain barrier (BBB) is regulated. A few years ago, we launched a project to determine the impact of sleep fragmentation and chronic sleep restriction on BBB functions, including permeability to fluorescent tracers, tight junction protein expression and distribution, glucose and other solute transporter activities, and mediation of cellular mechanisms. Recent publications and relevant literature allow us to summarize here the sleep-BBB interactions in five sections: (1) the structural basis enabling the BBB to serve as a huge regulatory interface; (2) BBB transport and permeation of substances participating in sleep-wake regulation; (3) the circadian rhythm of BBB function; (4) the effect of experimental sleep disruption maneuvers on BBB activities, including regional heterogeneity, possible threshold effect, and reversibility; and (5) implications of sleep disruption-induced BBB dysfunction in neurodegeneration and CNS autoimmune diseases. After reading the review, the general audience should be convinced that the BBB is an important mediating interface for sleep-wake regulation and a crucial relay station of mind-body crosstalk. The pharmaceutical industry should take into consideration that sleep disruption alters the pharmacokinetics of BBB permeation and CNS drug delivery, being attentive to the chrono timing and activation of co-transporters in subjects with sleep disorders.

Delta sleep-inducing peptide (DSIP): a still unresolved riddle

Delta sleep-inducing peptide (DSIP) was isolated from rabbit cerebral venous blood by Schoenenberger-Monnier group from Basel in 1977 and initially regarded as a candidate sleep-promoting factor. However, the link between DSIP and sleep has never been further characterized, in part because of the lack of isolation of the DSIP gene, protein and possible related receptor. Thus the hypothesis regarding DSIP as a sleep factor is extremely poorly documented and still weak. Although DSIP itself presented a focus of study for a number of researchers, its natural occurrence and biological activity still remains obscure. DSIP structure is different from any other known representative of the various peptide families. In this mini-review we hypothesize the existence of a DSIP-like peptide(s) that is responsible (at least partly) for DSIP-like immunoreactivity and DSIP biological activity. This assumption is based on: (i) a highly specific distribution of DSIP-like immunoreactivity in the neurosecretory hypothalamic nuclei of various vertebrate species that are not particularly relevant for sleep regulation, as revealed by the histochemical studies of the Geneva group (Charnay et al.); (ii) a large spectrum of DSIP biological activity revealed by biochemical and physiological studies in vitro; (iii) significant slow-wave sleep (SWS) promoting activity of certain artificial DSIP structural analogues (but not DSIP itself!) in rabbits and rats revealed by our early studies; and (iv) significant SWS-promoting activity of a naturally occurring dermorphin-decapeptide that is structurally similar to DSIP (in five of the nine positions) and the sleep-suppressing effect of its optical isomer, as revealed in rabbits. Potential future studies are outlined, including natural synthesis and release of this DSIP-like peptide and its role in neuroendocrine regulation.

Effect of delta-sleep inducing peptide-containing preparation Deltaran on biomarkers of aging, life span and spontaneous tumor incidence in female SHR mice

From the age of 3 months until their natural deaths, female Swiss-derived SHR mice were subcutaneously injected 5 consecutive days every month with 0.1 ml of normal saline (control) or with 2.5 microg/mouse (approximately 100 microg/kg) of delta-sleep inducing peptide (DSIP, Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu) as the preparation Deltaran solved in 0.1 ml of saline. There were 54 mice in each group. The results of this study show that the treatment with Deltaran did not influence food consumption, but decreased the body weight of mice; it slowed down the age-related switching-off of estrous function; it decreased by 22.6% the frequency of chromosome aberrations in bone marrow cells; it did not influence mean life span; and it increased by 17.1% life span of the last 10% of the survivors and by 24.1% maximum life span in comparison with the control group. We also found that treatment with Deltaran significantly decreased total spontaneous tumor incidence (by 2.6-fold), mainly mammary carcinomas and leukemias in mice as compared with the control group. This is the first report on geroprotector and anticarcinogenic effect of DSIP-containing preparation Deltaran.

Generation of the melatonin endocrine message in mammals: a review of the complex regulation of melatonin synthesis by norepinephrine, peptides, and other pineal transmitters

Melatonin, the major hormone produced by the pineal gland, displays characteristic daily and seasonal patterns of secretion. These robust and predictable rhythms in circulating melatonin are strong synchronizers for the expression of numerous physiological processes in photoperiodic species. In mammals, the nighttime production of melatonin is mainly driven by the circadian clock, situated in the suprachiasmatic nucleus of the hypothalamus, which controls the release of norepinephrine from the dense pineal sympathetic afferents. The pivotal role of norepinephrine in the nocturnal stimulation of melatonin synthesis has been extensively dissected at the cellular and molecular levels. Besides the noradrenergic input, the presence of numerous other transmitters originating from various sources has been reported in the pineal gland. Many of these are neuropeptides and appear to contribute to the regulation of melatonin synthesis by modulating the effects of norepinephrine on pineal biochemistry. The aim of this review is firstly to update our knowledge of the cellular and molecular events underlying the noradrenergic control of melatonin synthesis; and secondly to gather together early and recent data on the effects of the nonadrenergic transmitters on modulation of melatonin synthesis. This information reveals the variety of inputs that can be integrated by the pineal gland; what elements are crucial to deliver the very precise timing information to the organism. This also clarifies the role of these various inputs in the seasonal variation of melatonin synthesis and their subsequent physiological function.

The effects of delta sleep-inducing peptide on incidence and severity in metaphit-induced epilepsy in rats

The effects of delta sleep-inducing peptide (DSIP) on metaphit- (1-(1(3-isothiocyanatophenyl)-cyclohexyl) (piperidine)-) induced audiogenic seizures in adult male Wistar rats were studied. The animals were divided into four experimental groups: 1. saline injected; 2. metaphit administered (10 mg x kg (-1)); 3. metaphit administered plus DSIP injected (dose range 0.1-1 mg x kg (-1)) and 4. DSIP injected (1 mg x kg (-1)). Upon treatment, the rats were exposed to sound stimulation ( 100 +/- 3 dB, 60 s) at hourly intervals and the incidence and severity (running, clonus and tonus) of seizures were analyzed. In most animals, metaphit led to EEG abnormalities and elicited epileptiform activity recorded as spikes, polyspikes and spike-wave complex and increased power spectra. Time-course studies revealed the peak of convulsive activity 7-12 h after the injection in metaphit-treated rats. DSIP acted as an anticonvulsant and the most potent anticonvulsive dose of 1 mg x kg (-1)significantly increased power spectra of deltawaves (2-11 h) in comparison with the saline-control group and decreased the incidence and duration of convulsive response, as well as mean seizure grade of metaphit-induced convulsions. These results suggest that DSIP should be considered as having potential anticonvulsant activity in this animal model.

Essential fatty acids are mediators of brain biochemistry and cognitive functions

Major advances have been made in understanding the biochemistry of essential fatty acids (FA) and their interactions with metabolic pathways leading to the production of longer and more complex fatty acids and lipids. Less understood are the roles played by FA which are known to affect neurotransmitters, peptides, releasing factors, hormones, and a variety of physiological and cognitive processes. Based on empirical findings we propose that (a) FA exert a controlling function in the modulation of neuronal membrane fluidity, and (b) the critical factor in FA action and efficacy is not absolute level but rather the ratio between various groups of FA. This approach unifies the biochemical and cognitive results obtained from many different and unrelated fields of research.

Delta-sleep-inducing peptide and its analogs and the serotoninergic system in the development of anticonvulsive influences

Experiments on rats were carried out to study the effects of administration of delta-sleep-inducing peptide (DSIP) and its analogs (9-14) into the reticular part of the substantia nigra and ventral hippocampus on picrotoxin- and kainate-induced epileptic activity. Additionally, the uptake of [3H]tryptophan by brain structures was studied. Intranigral and intrahippocampal microinjections of peptide and its analogs were found to have anticonvulsant effects against both picrotoxin- and kainate-induced epileptic activity. Studies of the effects of DSIP and its structural analogs on the uptake of tryptophan by brain structures showed that peptides predominantly increased uptake of this amino acid. It is suggested that brain structures which modulate tryptophan uptake are largely responsible for the anticonvulsant actions of DSIP and its analogs. The results obtained here provide evidence that the serotoninergic system is not of key importance in mediating the anticonvulsant effects of DSIP and its analogs.

Essential fatty acids and sleep: mini-review and hypothesis

The neurochemical basis of sleep mechanisms (onset and maintenance) is still controversial although the phenomenon itself is known to be mediated by more than a single molecule. The list of suggested endogenous sleep substances is rather long, and there is no single 'sleep center' identified in the brain. The role of fatty acids, and essential fatty acids in particular, has been ignored in sleep research. This review proposes an integration of the current knowledge about the effects of fatty acids in sleep neurochemistry, wherein fatty acids are seen to exert a direct effect on neuronal membrane structure or indirectly on the dynamics of biochemical compounds (complex lipids, prostaglandins, neurotransmitters, amino acids, interleukins) necessary for the initiation and maintenance of sleep.

Human plasma DSIP decreases at the initiation of sleep at different circadian times

Nocturnal plasma delta sleep-inducing peptide-like immunoreactivity (DSIP-LI) was determined serially in seven healthy male subjects. Time courses during nocturnal sleep (2300-0800 h), nocturnal sleep deprivation (2300-0500 h), and morning recovery sleep (0500-0800 h) after sleep deprivation were compared. A significant decrease in plasma DSIP-LI was found at the transition from wakefulness to sleep in both evening sleep (2300 h) and morning recovery sleep (0500 h). Time courses were accompanied by physiological changes in sleep electroencephalographic slow-wave activity, and in plasma concentrations of cortisol and human growth hormone. No sleep stage specificity was found. It is concluded that DSIP is influenced by the initiation of sleep.

The influence of the delta-sleep-inducing peptide on convulsive activity

Data are presented in this paper on the influence of the delta-sleep-inducing peptide (DSIP) on various forms of convulsive activity. The capacity of this peptide to suppress convulsive activity in foci created in the cerebral cortex by the application of strychnine has been demonstrated in experiments on cats. It has been established in experiments on rats that DSIP determines the later development of the convulsive kindling syndrome, and prevents the development of convulsions in mice induced by bicuculline, picrotoxin, and corazol, but is devoid of such action in relation to thiosemicarbazide and strychnine. It was demonstrated that the anticonvulsant action of DSIP is associated with its influence on the reticular portion of the substantia nigra. The lowest level of this peptide itself has been discovered, in the reticular portion of the substantia nigra at the late stages of pharmacological kindling. It is inferred that DSIP may represent one of the factors of the endogenous control of the excitability of the brain.

Altered consciousness: pharmacology and phenomenology BAP Summer Meeting, York, July 1991: Sleep and general anaesthesia as altered states of consciousness

In this article parallels are drawn between sleep and anaesthesia. Both can be described as 'behavioural states' in which stimulation and inhibition of certain neuronal groups will give rise to specific psychological states. The neuronal mechanisms leading to these states are reviewed and compared. Sensory information flow through the thalamus is reduced in sleep and anaesthesia, the thalamic gating being controlled by other areas of the brain including the sensory cortex. Thus a feedback loop may exist with the brain determining its own level of arousal. Anaesthesia increases gating at the thalamus and thus specifically reduces arousal. Consciousness is a specific attribute of the brain and is not required for the processing of sensory stimuli and learning, both of which have been shown to occur during sleep and anaesthesia. The implications of these findings for monitoring awareness during anaesthesia are discussed.