Inessa I. Mikhaleva

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((R))-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 microgram/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.

Effects of delta-sleep inducing peptide (DSIP) and some analogues on the activity of monoamine oxidase type A in rat brain under hypoxia stress

Metabolic effects of delta‐sleep inducing peptide (DSIP) under hypoxia stress were investigated in rats subjected to short‐term hypoxic conditions (about 0.26 Bar). It was found that DSIP partially restricted stress‐induced changes in activity of mitochondrial monoamine oxidase type A (MAO‐A) and serotonin level in rat brain. A number of DSIP analogues was tested and among them there were some compounds with enhanced ability to counteract hypoxia induced changes in MAO‐A activity and serotonin content in comparison with native neuropeptide.

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 effect of some peptides from the hibernating brain on Ca2+ current in cardiac cells and on the activity of septal neurons

The effects of the peptides TSKYR and DY isolated from the brain of hibernating ground squirrels on Ca2+ current were studied. TSKYR activated Ca2+ current in frog auricle fibers and in single cells from frog ventricle whereas DY blocked Ca2+ current in both preparations. In isolated rat and ground squirrel cardiocytes, TSKYR had no effect on Ca2+ current, and DY increased it. In brain slices of rat, DY blocked the activity of medial septal neurons. TSKYR increased activity of septal neurons at the initial phase, which was followed by decrease of neuronal activity.

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.

Seizure-protecting effects of kyotorphin and related peptides in an animal model of epilepsy

Administration of peptides kyotorphin (KT), neokyotorphin (NKT), and d-ser-2-NKT into the lateral brain ventricle (10 nmol) increased the latency and attenuated the severity of picrotoxin-induced convulsions in rats. Anticonvulsive effects of the peptides were also observed after their administration into the CA1 hippocampi (2.5, 5, 10 nmol), with the order of potency d-ser-2-NKT-->NKT-->KT. When injected into the substantia nigra reticulata, the 10 nmol dose of NKT and d-ser-2-NKT displayed equal seizure-protecting effect, which was higher than that for KT. It is concluded that kyotorphin and its analogs provide structure-dependent, dose-dependent, and target site-dependent antiepileptic effect.

JmjC-domain-containing histone demethylases of the JMJD1B type as putative precursors of endogenous DSIP.

Delta sleep inducing peptide (WAGGDASGE, DSIP) is a well known multifunctional regulatory peptide. Numerous studies have confirmed its stress-protective and adaptive activity which is independent of the origin or nature of the stress or other harmful factors. However, the biosynthetic origin of DSIP remains obscure, since nothing is known of its protein precursor(s) and their encoding gene(s). We have performed a comprehensive analysis of available gene and protein databases for homologous peptide sites within mammalian resources including man. A family of Jumonji C (JmjC)-domain-containing histone demethylases was shown to contain a sequence fragment closely homologous to DSIP. One type of these ubiquitous and phylogenetically ancient proteins encoded by JMJD1B gene includes the WKGGNASGE sequence that differs from DSIP by only 2 amino acid residues in positions 2 and 5. The respective peptide was synthesized and its biological effects were evaluated in a preliminary way in the forced swimming and antitoxic tests. We suggest that the histone demethylases of the JmjC-group containing DSIP-related region can be considered as possible protein precursors of endogenous peptides with DSIP-like activity.

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

PROBLEM 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. METHODS 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. RESULTS AND CONCLUSIONS 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.

The Effect of Delta-Sleep-Inducing Peptide on the Lifespan and Incidence of Spontaneous Tumors in Mice

Delta-sleep-inducing peptide (DSIP, Trp-AlaGlyGly -Asp-Ala-Ser-Gly-Glu) is a neuromodulating peptide bioregulator with a polyfunctional and prolonged effect [1–5]. One of the characteristic effects of this peptide is its ability to suppress the stress-induced lipid peroxidation of cell membranes in the brain and peripheral areas. It was found that DSIP is also able to modulate the activity of some membrane-bound and integral membrane enzymes that play a key role in the regulation of cell and tissue metabolism. It was also shown that DSIP regulates the respiratory activity of rat brain mitochondria and prevents its decrease induced by experimental hypoxia [1–5]. An important property of DSIP is its stress-protective and adaptogenic activities [1, 6]. On the other hand, it is known that antioxidants and adaptogens may also have a geroprotective effect, because one of the main mechanisms of senescence is related to the damaging effect of free radicals [7, 8].

Mechanism of geroprotective action of delta-sleep inducing peptide

Subcutaneous injections of exogenous delta-sleep inducing peptide (DSIP) to rats aged 2–24 months (100 μg/kg body weight, 5-day series of injections) have been shown to efficiently prevent oxidative damage to lipids and malonic dialdehyde accumulation in the tissues and blood plasma of rats of different ages. DSIP has a strong antioxidant effect mediated by the activation of various endogenous mechanisms of antioxidant protection both in cells and in the intercellular liquid containing high molecular weight and low molecular weight regulators of free-radical processes. DSIP has a stimulatory effect on the activity of superoxide dismutase, catalase, and ceruloplasmin, and affects the concentration of nonenzymatic antioxidantsurea and ureic acid; the physiological aging of the organism is accompanied by suppression of antioxidant protection mechanisms. DSIP increases the capacity of endogenous antioxidant protection systems in the tissues and blood, mostly by stimulating the components of the enzymatic antioxidant system, especially in late ontogenesis.