Delta Sleep-inducing Peptide Research Articles

Delta-Sleep-Inducing Peptide Potentiates Anticonvulsive Activity of Valproate against Metaphit-Provoked Audiogenic Seizure in Rats

The effect of delta-sleep-inducing peptide (DSIP) on the anticonvulsive activity of a nonprotective valproate (VPA) dose in a metaphit model of generalized, reflex audiogenic seizures in adult Wistar rats was studied. The animals that received metaphit (10 mg/kg) were exposed to audiogenic stimulation (100 ± 3 dB, 60 s) at hourly intervals. Metaphit-treated rats displaying seizures in 8 previous tests were i.p. injected with VPA (50 mg/kg) or DSIP (1.0 mg/kg) or their combination. Latency to seizure was behaviorally assessed. The EEGs and power spectra were recorded and analyzed. Neurotoxicity was evaluated by the chimney test. DSIP or VPA alone expressed no significant effect on the latency duration, but their combination significantly prolonged latency to seizure during 6 h after injection, while inducing no significant motor impairment. Neither the applied drugs nor their combination abolished metaphit-provoked EEG epileptiform activity. The results show that DSIP potentiated anticonvulsive effects of a nonprotective VPA dose in a metaphit model of audiogenic seizures without influencing its neurotoxicity.

Effect of delta sleep-inducing peptide on macromolecule biosynthesis in brain tissue of stressed rodents

For evaluation of the nature of adaptogenic properties of delta sleep-inducing peptide we studied the effect of this substance on macromolecule biosynthesis in the brain of rats and mice exposed to burn injury and psychoemotional stress, respectively. Anabolic activity of delta sleep-inducing peptide depended on the purpose of adaptation corresponding to the type of stress.

Morphochemical study of hippocampus of August rats after systemic treatment with amphetamine followed by injection of delta sleep-inducing peptide

Quantitative interferometry showed that chronic amphetamine administration to August rats (2.5 mg/kg/day for 3 weeks) increased the area of neuronal cytoplasm and nuclei and content and concentrations of proteins in hippocampal CA3 neurons. These changes persisted after single injection of delta sleep-inducing peptide (60 microg/kg). The reaction of the entire neuronal population of hippocampal CA3 neurons to amphetamine is similar.

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.

Interaction of delta sleep-inducing peptide and its analogues with cellular membranes: A structure-function analysis

The possibility of a correlation between the membrane properties of the delta sleep-inducing peptide (DSIP) and its analogues and their biological activity in vivo was examined by a comparative study of the membrane effects of these peptides. The peptides exhibiting biological activity in vivo were shown to cause a statistically reliable disordering of lipids in thrombocyte plasma membranes similar to the effect of DSIP. The membrane effect of the D-Val2, D-Tyr2, and Tyr1, Pro2 analogues of DSIP had the same bimodal dose dependence characteristic of natural DSIP. Only a slight nonspecific lipid disordering was registered for Trp-Asp-Ala-Ser-Gly-Glu, a biologically inactive hexapeptide analogue. These results indicate a correlation between the biological activity of the peptides during in vivo tests and their membrane properties in vitro. The structure-function relationship was studied within the group of DSIP analogues examined in vitro. The DSIP modeling effect, especially pronounced under the action of stress factors, was suggested to be directly associated with the ability of DSIP to change the dynamic structure of biological membranes.

Synthesis of Fragment Derivatives of Delta Sleep-inducing Peptide (1-4) Catalyzed by Enzymes in Organic Solvents

Synthesis of two fragment derivatives of delta sleep-inducing peptide (DSIP) (1-4), Boc-Trp-Ala-Gly-GlyNH-NHPh (1) and Boc-Trp-Ala-Gly-GlyOEt (2), catalyzed by proteases via 2+2 or 1+3 synthetic routes with different protecting groups at C-terminal in organic solvents was reported. The yield of N-Boc tetrapeptide with phenylhy-drazinyl protecting carboxyl group at C-terminal (1) was higher than that of N-Boc tetrapeptide ethyl ester (2) by2+2 route. The factors influencing the synthetic yield of the fragments of DSIP (1-4) were discussed.

Antiepileptic activity of delta sleep-inducing peptide and its analogue in metaphit-provoked seizures in rats

Previous studies have shown that humoral, endogenous and somnogenic, delta sleep-inducing peptide (DSIP) has influence on insomnia, pain, adaptation to stress, epilepsy, etc. We investigated the potential of DSIP and its analogue DSIP-12 (a nonapeptide with alanine in position 2 of DSIP molecule substituted by beta-alanine) to antagonize metaphit (1-[1(3-isothiocyanatophenyl)-cyclohexyl]piperidine) induced generalized, reflex audiogenic seizures in adult male Wistar albino rats. The rats divided in four groups received (i.p.): saline; metaphit; metaphit+DSIP; and metaphit+DSIP-12, respectively. Metaphit-treated animals displaying seizure in eight previous tests received DSIP or DSIP-12 and afterwards audiogenic stimuli were applied at hourly intervals for the next 30 h. The animals were exposed to sound stimulation 60 min after metaphit administration and further on at hourly intervals. Incidence and severity of seizures were behaviorally analyzed. Selected EEGs and power spectra were recorded and analyzed. Metaphit led to hypersynchronous epileptiform activity (polyspikes and spike-wave complexes) and increased power spectra 0.5-30 h after the treatment. Severity of metaphit seizures increased with time to reach the peak 7-12 h after injection. DSIP and DSIP-12 significantly (*P<0.05 and **P<0.01) increased in delta and theta frequency bands and decreased the incidence, mean seizure grade and duration of metaphit convulsions. The results suggest that DSIP and DSIP-12 may be considered as potential antiepileptics in the animal model, DSIP-12 being more efficient than DSIP.

Delta-sleep inducing peptide and neuronal activity after glutamate microiontophoresis: the role of NMDA-receptors

The influence of microiontophoretic application of delta-sleep inducing peptide (DSIP) on a neuronal activity of sensorimotor brain cortex, dorsal hippocampus, ventral anterior thalamic nucleus and lateral hypothalamus was studied under the effects of glutamate and MK-801, a N-methyl- d-aspartate non-competitive antagonist, on male Wistar rats. DSIP microiontophoresis predominantly activated neurons of various brain regions, in particular, dorsal hippocampus and ventral anterior thalamic nucleus. A preliminary DSIP microiontophoresis prevented the augmentation of a neuronal activity in the studied structures under glutamate microiontophoresis. After MK-801 microiontophoresis the number of neurons activated by the DSIP significantly decreased. It is suggested that DSIP effects on the neuronal activity in the sensorimotor brain cortex, dorsal hippocampus, ventral anterior thalamic nucleus and lateral hypothalamus might be mediated by the NMDA-receptors.

Dizocilpine blocks the effects of delta sleep-inducing peptide-induced suppression of c-fos gene expression in the paraventricular nucleus of the hypothalamus in rats.

The characteristics of the actions of the non-competitive blocker of NMDA receptors dizocilpine on the expression of the early c-fos gene in the paraventricular nuclei of the hypothalamus were studied in rats with different predicted susceptibilities to emotional stress in conditions of treatment with delta sleep-inducing peptide. The results showed that prior treatment with dizocilpine blocked reductions in c-fos expression induced by delta sleep peptide.

Behavioral and electroencephalographic effects of delta sleep inducing peptide and its analogue on metaphit-induced audiogenic seizures in rats

Delta sleep inducing peptide (DSIP) is well known natural somnogenic peptide that has many other physiological functions. DSIP analogues representing hepta- and octapeptides (also known as long) as well as tetrapeptide (termed short, used in our experiments) were synthesized with a view to evaluate the peptide specificity in sleep. The effects of DSIP and its analogue DSIP1-4 on metaphit 1-[1(3-isothiocyanatophenylciclohexyl)-piperidine] induced audiogenic seizures were evaluated in rats. Male Wistar albino rats were divided into 4 groups: 1. Saline; 2. Metaphit; 3. Metaphit + DSIP, and 4. Metaphit + DSIP1-4. To examine the blocking effects of DSIP and its analogue on fully developed metaphit seizures, the last two groups were injected after the 8th audiogenic testing. Animals were injected with metaphit (10 mg/kg) intraperitoneally (i.p.) and exposed to sound stimulation (100 +/- 3 dB, 60 s) at hourly intervals. The incidence and severity (running, clonus and tonus) of seizures were analyzed. For electroencephalographic (EEG) recordings, three gold-plated electrodes were used. Convulsive behavior was assessed by incidence of motor seizure and by seizure severity grade, determined by descriptive rating scale ranging from 0 to 3: 0--no response, 1--wild running only; 2--wild running followed by clonic seizures of all four limbs with body rollover; 3--wild running progressing to generalized clonic convulsions followed by tonic extension of fore- and hind legs and tail. Sound onset, seizure events, and sound offset, along with the animal's behavior (convulsive or other) were characterized with EEG changes. In most animals, the administration of metaphit resulted in electroencephalographic abnormalities, elicited epileptiform activity in the form of spikes, polyspikes and spike-wave complexes. Maximum incidence and severity of metaphit convulsions occurred 8 h after the injection (9/12, 75%), then abated gradually and disappeared 30 h later. Both DSIP and DSIP1-4 significantly increased the power spectra of d waves and decreased the incidence of seizures, mean seizure grade and tonic component of metaphit-induced convulsions. Metaphit has been shown to induce audiogenic seizures after systemic and intracerebroventricular administration and to be truly epileptic in small rodents, although about 8 h after metaphit administration, the power spectra increased and was more intense in the period of sound onset and seizure events. Taken together, DSIP makes an optimal ratio between inhibitory and excitatory amino acid neurotransmitters and may represent one of the endogenous control systems of the brain, thus exerting the protective effect against the seizures. The results obtained throughout the present study corroborate and broaden the data on prolonged antiepileptic DSIP effect. The results of the present study strongly suggest that treatment of adult rats with DSIP and its analogue DSIP1-4 should be considered as potential natural antiepileptics.

Delta sleep-inducing peptide and its tetrapeptide analogue alleviate severity of metaphit seizures

The effects of delta sleep-inducing peptide (DSIP) and its tetrapeptide analogue, DSIP(1-4), on metaphit-induced audiogenic seizures were studied. Five groups of adult male Wistar rats were intraperitoneally treated with (1) saline, (2) metaphit, (3) DSIP, (4) metaphit+DSIP and (5) metaphit+DSIP(1-4). To examine blocking effects of DSIP and its analogue on fully developed metaphit seizures, the last two groups were injected after the eight audiogenic testing. The rats were stimulated using electric bell (on the top of the cage, generating 100±3 dB and frequency 5–8 kHz, for 60 s) 1 h after metaphit and afterwards at hourly intervals during the experiment. For EEG recordings and power spectra, three gold-plated screws were implanted into the skull. In metaphit-treated animals, EEGs appeared as polyspikes and spike-wave complexes while the power spectra were increasing for 30-h period. The incidence and severity of metaphit-induced audiogenic seizures reached peak value 7–12 h after the injection. Both DSIP and DSIP(1-4) significantly increased power spectra of delta waves and decreased incidence of seizures, mean seizure grade and tonic component of metaphit-induced convulsions. Taken together, these results suggest that DSIP and its analogue DSIP(1-4) should be considered as potential antiepileptics.

The Delta-Sleep Inducing Peptide in Cerebral Mechanisms of Emotional Stress

The problem of the anti-stressor effect of the delta-sleep inducing peptide (DSIP) and of its neurophysiological mechanisms of action is considered. Physiological data are exposed that indicate an intraventricular administration of DSIP in rats to results in an increase of resistance to emotional stress, according to behavioral and autonomous reactions, and in a decrease of excitability of the brain structures responsible for protective reaction. Radioimmunological evidence is presented for the resistance of animals to emotional stress to depend on the content in hypothalamus of certain oligopeptides, such as β-endorphin, DSIP, and the substance P. It was shown that animals resistant to emotional stress had a higher content of these oligopeptides in hypothalamus than those predisposed to stress. The issue is discussed that the prolonged anti-stressor effects after the DSIP administration are determined by considerable changes of the content of other polypeptides and hormones in hypothalamus and blood, which are involved in the reaction under the effect of DSIP.

Delta sleep inducing peptide (DSIP): effect on respiration activity in rat brain mitochondria and stress protective potency under experimental hypoxia

Neuromodulatory delta sleep inducing peptide (DSIP) seems to be implicated in the attenuation of stress-induced pathological metabolic disturbances in various animal species and human beings. Mitochondria, as cell organelles, are considered especially sensitive to stress conditions. In this work, the influence of DSIP and Deltaran ®—a recently developed product based upon DSIP—on processes of oxidative phosphorylation and ATP production in rat brain mitochondria and rat brain homogenates was studied. A polarographic measurement of oxygen consumption was applied to evaluate the impact of DSIP on maximal rates of mitochondrial respiration and coupling of respiration to ATP production. We provide evidence that DSIP affected the efficiency of oxidative phosphorylation on isolated rat brain mitochondria. This peptide significantly increased the rate of phosphorylated respiration V3, while the rate of uncoupled respiration V DNP remaining unchanged. It enhanced the respiratory control ratio RCR and the rate of ADP phosphorylation. DSIP and Deltaran exhibited the same action in rat brain homogenates. We also examined the influence of DSIP under hypoxia when mitochondrial respiratory activity is altered. In rats subjected to hypoxia, we detected a significant stress-mediated reduction of V3 and ADP/t values. Pretreatment of rats with DSIP at the dose of 120 μg/kg (i.p.) prior to their subjection to hypoxia completely inhibited hypoxia-induced reduction of mitochondrial respiratory activity. The revealed capacity of DSIP to enhance the efficiency of oxidative phosphorylation found in vitro experiments could contribute to understanding pronounced stress protective and antioxidant action of this peptide in vivo.

Efficiency of ultralow doses of antibodies to S100 protein and delta sleep-inducing peptide in rats with anxious depression.

We studied the effects of single peroral treatment with antibodies against S100 protein and delta sleep-inducing peptide in ultralow doses on behavioral characteristics of rats with anxious depression produced by acute stress (unavoidable electrical shock). Stress-produced behavioral changes and anxiolytic activity of antibodies were determined using the elevated plus-maze, open field, and tail suspension tests. High efficiency of the mixture of antibodies against S100 protein and delta sleep-inducing peptide was observed in all tests. Anxiolytic activity of anti-S100 antibodies (although less pronounced than that of the mixture of antibodies) was revealed in the elevated plus-maze and tail suspension test.

Antidepressant properties of antibodies to serotonin, brain-specific S100 protein, and delta sleep-inducing peptide.

Potentiated antibodies to delta sleep-inducing peptide and S100 protein produced an antidepressant effect in Wistar rats. This effect was more pronounced after combined treatment with these antibodies. It can be assumed that these antibodies modulate neurobiological mechanisms of positive emotional reinforcement and, therefore, affect the resistance to depression associated with psychoemotional stress.

Antibodies to delta sleep-inducing peptide in ultralow doses: study of the effect by enzyme immunoassay.

The effects of potentiated homeopathic preparations containing antibodies to delta sleep-inducing peptide in ultralow doses were studied by enzyme immunoassay. Experiments were performed with the following immunochemical reagents: antigens of delta sleep-inducing peptide conjugated to various macromolecular carriers and specific antigens. Antibodies to delta sleep-inducing peptide were synthesized in dilutions of C3, C6, C12, C50, and C200. Enzyme immunoassay showed that test preparations of antibodies in dilutions of 1:400-1:3200 produce the combined effect on immune complex formation. The proposed method holds much promise for identification of medicinal preparations in ultralow doses.

Biochemical regulation of non-rapid-eye-movement sleep.

The concept, that sleep regulatory substances (sleep factors) exist, stems from classical endocrinology and is supported by positive transfer experiments in which tissue fluids obtained from sleepy or sleeping animals elicited sleep when injected into recipient animals. The transfer experiments concluded with the identification of four sleep factors: delta sleep-inducing peptide (DSIP), uridine, oxidized glutathione, and a muramyl peptide. A physiological sleep regulatory role, however, has not been determined for these substances. In contrast, transfer experiments did not play a part in the development of the strong experimental evidence that implicated the currently known sleep factors in sleep regulation. These substances include adenosine, prostaglandin D2 (PGD2), growth hormone-releasing hormone (GHRH), interleukin-1 (IL1) and tumor necrosis factor (TNF). They promote non-REMS in various species, inhibition of their action or endogenous production results in loss of spontaneous sleep, and their synthesis and/or release display variations correlating with sleep-wake activity. Although the source of these substances vary they all enhance sleep by acting in the basal forebrain/anterior hypothalamus--preoptic region. It is also characteristic of these substances that they interact in multiple ways often resulting in mutual stimulation or potentiation of each other. Finally, there is a third group of substances whose significance in sleep regulation is less clear but for which there are two or more lines of evidence suggesting that they may have a role in modulating non-REM sleep (NREMS). This group includes oleamide, cortistatin, cholecystokinin (CCK), insulin, and nitric oxide (NO). More sleep regulatory substances are likely to be discovered in the future although it is a long and difficult process requiring multiple laboratories to generate sufficient convincing data to implicate any one of them in sleep regulation.

Antibodies to delta sleep-inducing peptide in ultralow doses: effect on the behavior of male mice with anxiety and depressive syndrome.

We studied the effect of antibodies to delta sleep-inducing peptide in ultralow doses on the behavior of male mice with anxiety and depressive syndrome resulting from competitive interactions. The behavior of animals was studied in the elevated plus-maze, partition, and forced swimming tests. The preparation produced a strong anxiolytic effect, which was especially pronounced in animals with anxiety and depressive syndrome.

Flexible crosslinked benzhydryl support for gel-phase peptide synthesis.

An amphiphilic support was developed by the suspension polymerization of styrene and 1,4-butanediol dimethacrylate. The copolymer was converted to benzhydryl resin, BDDMA-PS-BH, by a two-step polymer analogous reaction. This resin was employed as a support for the synthesis of delta sleep inducing peptide (DSIP), Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu, in high yield and purity by Fmoc / t-Bu tactics.

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 kg −1); 3. metaphit administered plus DSIP injected (dose range 0.1–1 mg kg −1) and 4. DSIP injected (1 mg 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 kg −1significantly increased power spectra of δwaves (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.