Corresponding author: Vladimir V. Gureev ( gureev@bsu.edu.ru ) Academic editor: Oleg Gudyrev
© 2021 Oleg V. Antsiferov, Roman F. Cherevatenko, Mikhail V. Korokin, Vladimir V. Gureev, Anastasia V. Gureeva, Mariya A. Zatolokina, Elena V. Avdeyeva, Lyudmila A. Zhilinkova, Inga M. Kolesnik.
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Citation:
Antsiferov OV, Cherevatenko RF, Korokin MV, Gureev VV, Gureeva AV, Zatolokina MA, Avdeyeva EV, Zhilinkova LA, Kolesnik IM (2021) A new EPOR/CD131 heteroreceptor agonist EP-11-1: a neuroprotective effect in experimental traumatic brain injury. Research Results in Pharmacology 7(4): 1-9. https://doi.org/10.3897/rrpharmacology.7.75301
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Introduction: EP-11-1 (UEHLERALNSS) is a short-chain erythropoietin derivative without have erythropoietic activity. It was created by modifying a peptide mimicking the spatial structure of the erythropoietin a-helix B pHBSP. One of the promising directions of its administration is the correction of morphofunctional disorders that occur in traumatic brain injury (TBI).
Materials and methods: The study was performed in 160 male Wistar rats, weighing 180–200 g.TBI was simulated using the drop-weight method. To assess the emerging morphofunctional disorders and a degree of their correction, we used the severity of neurological deficit, indicators of locomotor activity and exploration, a marker of brain injury S100B and morphological examination.
Results and discussion: The combined administration of a new EPOR/CD131 heteroreceptor agonist EP-11-1 with citicoline and trimetazidine led to a more pronounced correction of the neurological deficit when compared not only to the group of the ”untreated” animals, but also to the groups of animals to which these drugs had been administered as monotherapy (p < 0.05). The same tendency was also observed in the study of locomotor activity and exploration. A biochemical study showed that the administration of all three combinations led to a statistically significant (p < 0.05) decrease in the S-100B concentration compared not only to the group of “untreated” animals, but also to the groups of animals to which these drugs had been administered as a monotherapy.
Conclusion: The results of the conducted experiments prove the most pronounced positive dynamics in the combined administration of the new EPOR/CD131 heteroreceptor agonist EP-11-1with citicoline and trimetazidine.
traumatic brain injury, secondary failure, trimetazidine, erythropoietin derivatives.
Traumatic brain injury (TBI) is one of the most important problems of public healthcare and public at large. This is due to the prevalence of this type of traumatic injury, the severity of the consequences of TBI, and the significant economic loss caused by TBI (
Brain injury is divided into primary and secondary. The main causes of secondary injury include: increasing edema, extension of hematoma, secondary thrombosis, etc., which lead to the development of energy deficiency, excitotoxicity, oxidative stress, lipid peroxidation, neuroinflammation, inhibitory neurotransmitters deficiency, and apoptosis of the brain tissue cells (
In this regard, a promising point for the correction of morphofunctional disorders in TBI may be the prevention of an increase in Ca2+ within a cell and mitochondria, which will lead to a decrease in energy deprivation, inhibition of the mitochondrial macropore opening, and activation of caspases and apoptosis. In addition, a suppression of the glutamate release to some extent will reduce the phenomenon of excitotoxicity (
Another way to reduce excitotoxicity can be through the modulation of the release/absorption processes for such neurotransmitters as glutamate and GABA by platelets (
There is some evidence of good prospects of using EPOR/CD131 heteroreceptor agonists. At the same time, various cytoprotective effects are realized by the activation of multiple paths: anti-ischemic, anti-apoptotic, anti-oxidant, endothelioprotective, etc. (
Another promising mechanism to be logically included in the complex therapy is the phospholipase A2 inhibition. This will slow down the membrane phospholipid degradation and the formation of arachidonic acid. On the one hand, this will manifest in a membrane-stabilizing effect, and, on the other hand, in a decrease in neuroinflammation and the formation of reactive oxygen species (
The classic activator of the EPOR/CD 131 heteroreceptor is erythropoietin, which has an erythropoietic activity and a large size as disadvantages. Erythropoietin short-chain derivatives, the classic example of which is pHBPS, are most promising in this regard (
In connection with the above, when selecting the combinations of pharmacological agents for the study, the choice was made in favor of citicoline because of its ability to inhibit phospholipase A2, to modulate the release of various neurotransmitters, promoting neuroregeneration, and to inhibit apoptosis through the mitochondrial mechanisms (
The study was supported by the grant of the President of the Russian Federatin MD-757.2020.7.
Aim of the study: to demonstrate the prospects of administrating a new EPOR/CD131 heteroreceptor agonist – EP-11-1 – for the correction of the morphofunctional disorders in experimental TBI in rats.
The experiment was performed at the Center for Preclinical and Clinical Studies of Belgorod State National Research University. “The Rules of Laboratory Practice”, approved by Order No.708n of the Ministry of Health of the Russian Federation of 23.08.2010, in strict compliance with “The European Convention for the Protection of Vertebrate Animals Used for Experiments or for Other Scientific Purposes” (Directive2010/63/EU). The experimental studies were approved by the Bioethical Commission of Belgorod State National Research University. Vivisection was performed in compliance with the ethical principles of treating laboratory animals outlines in “The European Convention for the Protection of Vertebral Animals Used for Experimental and Other Scientific Purposes”. CETS No.123.
The experimental study was performed in 160 male Wistar rats, weighing 180–200 g. The animals were kept in accordance with the rules of laboratory practice for preclinical studies on the territory of the Russian Federation. The animals were kept under the standard conditions corresponding to the sanitary rules on the organization, equipment and maintenance of experimental biological clinics (vivariums) No. 1045-73, approved by the Ministry of Health of the USSR on 06.04.1973 and GOST R 53434-2009. The individually ventilated cages (Tecniplast S.p.A., Italy) designed for keeping small laboratory animals. The bedding was sawdust, sterilized by ultraviolet irradiation. Special pellet feed for small laboratory rodents and pre-treated water disinfected with UV irradiation were used. In each cage, microclimate was created and supported by an individual ventilation system. All the animals had been acclimatized and quarantined for at least 10 days before the experiment.
Drop-weight TBI model was used in this study (
To assess the neurological deficit of the laboratory animals and its dynamics during the study, the following evaluation scales were used: the Stroke-Index McGraw scale modified by I. V. Gannushkina (
The impact of TBI and the studied compounds on behavior was evaluated in a standard Open Field behavioral test (
As a component of assessing the severity and dynamics of the condition of the animals with experimental TBI, we evaluated the level of S100B protein in the animals’ blood. Blood was sampled in all the studied groups on day 7. To do this, the left ventricle was punctured intercostally in the projection of the heart, and 2 ml of blood was sampled into the vacutainer. The concentration of S100B in blood was determined by the electrochemiluminescence immunoassay (ECLIA), using the test system for quantitation in vitro S100 (S100 A1B and S100 BB).
In the studied groups, after TBI simulation (intact group after anesthesia), in compliance with the principles of humane treatment of animals, the animals were sacrificed under anesthesia (chloral hydrate, 350 mg/kg) by a left ventricular puncture until complete bleeding.
For a morphological examination, cephalotomy was performed, followed by the extraction of the brain with the cerebellum. The resulting biomaterial (brain) was fixed in a 10% solution of neutral formalin. After fixation, a part of the cerebral cortex in the area of injury (frontoparietal region) was sectioned and embedded into paraffin, according to the standard method. Next, the sections, 5–7 microns thick, were made and stained with hematoxylin and eosin. Microscopy and photographing were carried out using an optical system consisting of a Leica CME microscope and a DCM-510 eyepiece camera at magnifications of ×100-, ×200- and ×400-fold, with documenting the images in the FUTURE WINJOE software included in the eyepiece camera package.
During the experimental study, the neuroprotective effect of trimetazidine was studied. Citicoline was used as a comparison drug. The possible results of the combined neuroprotective therapy were also evaluated.
Trimetazidine (Preductal MR, Servier, Russia) was administered 2 hours before the TBI simulation, intragastrically, at a dose of 6 mg/kg/day; the dose was divided into two administrations, with an interval of 12 hours, and the therapy was carried out throughout the entire period of the experiment (7 days) or before the animal was removed from the experiment. This dose corresponds to the recommended therapeutic dose in humans of 1 mg/kg (70 mg/day); the dose of the medication was recalculated using the generally accepted formula for interspecific dose scaling according to (Freireich M. et al. and Ulanova I. P).
Citicoline (Ceraxon, Ferrer Internacional, S. A., Spain): at an acute ischemic stroke and TBI, it is recommended to use the following dose schedule: 1000 mg every 12 hours from the first day after the diagnosis. Based on this, the dose for a rat weighing 180–200 g was calculated using the generally accepted formula for interspecific dose scaling. The drug administration was started 2 hours before the TBI simulation, intraperitoneally, at a dose of 170 mg/kg/day; the dose was divided into two administrations with a 12-hour interval, at the same point of time; the therapy was performed throughout the entire period of the experiment (7 days) or before the animal was removed from the experiment.
A new EPOR/CD131 heteroreceptor agonist EP-11-1 (UEHLERALNSS): the drug was administered 2 hours before the TBI simulation, intraperitoneally, at a dose of 20 mcg/kg/day (
All the experimental animals were divided into the following groups:
The statistical data were processed using the Statistica 10.0 software. Shapiro-Wilk and Spiegelhalter (normtest package) normality tests were performed for the obtained data; the equality of variances was assessed using the Levene’s test (lawstat package). Depending on the type of distribution and the equality of variances, the significance of the results obtained was evaluated using parametric (ANOVA) or non-parametric (Kruskal-Wallis test) one-way analysis of variance, and as a post-hoc analysis to identify intergroup differences, the Student’s t-test or the Mann-Whitney test were used, respectively, with the Benjamini-Hochberg correction for multiple tests. The results were considered reliable at p ≤ 0.05.
The TBI simulation led to a severe neurological deficit in the animals with some regression on day 7. In the groups administered with these pharmacological agents as a monotherapy, the indicators were statistically significantly different from the group of ”untreated” animals (TBI) (p < 0.05) (Table 1). However, the level of the intact group of animals was not reached.
The combined administration of a new EPOR/CD131 heteroreceptor agonist EP-11-1 with citicoline and trimetazidine led to a more pronounced improvement compared not only to the group of ”untreated” animals, but also to the groups of animals administered with these drugs as a monotherapy (p < 0.05) (Table 1). But the target level was not reached. In the group of animals administered with a combination of trimetazidine and citicoline, a statistically significant decrease in neurological deficit was observed compared to the TBI group, but there was no significant difference compared to the groups administered with these drugs as a monotherapy.
The TBI simulation led to a pronounced decrease in locomotor activity and exploration, as evidenced by a statistically significant (p < 0.05) decrease in the number of free-rearings and wall-rearings, and the distance covered for 3 minutes, as well as the time spent in the central zones compared to the group of the intact animals (Table 1). By day 7, there was some improvement in these indicators, but their level was significantly lower than in the intact animals (p < 0.05).
Monotherapies with the studied pharmacological agents improved the indicators of the locomotor activity and exploration on day 7; after the TBI simulation, as evidenced by a statistically significant (p < 0.05) increase in the number of free-rearings and wall-rearings, and an increase in the distance covered for 3 minutes compared to the group of the ”untreated” animals. In addition, in these groups, there was a statistically significant increase in the time spent in the central zones (p < 0.05) (Fig.
The effect of new EPOR/CD131 heteroreceptor agonist EP-11-1 on the S-100B concentration on day 7 in TBI. Note: # – р < 0.05 in comparison with the intact animals; * – р < 0.05 in comparison with the animals with TBI; y – р < 0.05 in comparison with monotherapy.
A study of locomotor activity and exploration on day 7 showed that a combined administration of EP-11-1 with citicoline statistically significantly increased the number of free-rearings and wall-rearings in comparison with the groups administered with these pharmacological agents as a monotherapy. In the group of animals administered with a combination of EP-11-1 with citicoline and trimetazidine, the distance covered reached the level of the intact animals, and the combined administration of EP-11-1 with trimetazidine had a statistically significant advantage in comparison with the same pharmacological agents used as a monotherapy.
In addition, in these groups, there was a statistically significant increase in the time spent in the central zones (p < 0.05) (Table 2). In the groups of animals that had been administered with the combinations of EP-11-1 with citicoline and trimetazidine, the time spent in the central zones reached the level of the intact animals (p < 0.05).
The study of biochemical markers of brain injury (protein S100B) showed its statistically significant increase (p < 0.05) in the blood on day 7 after the TBI simulation compared with the group of intact animals (Fig.
The study of biochemical markers of brain injury (protein S100B) in blood plasma showed that the administration of the combination of trimetazidine and a new EPOR/CD131 heteroreceptor agonist EP-11-1 with citicoline, as well as their combinations, led to a statistically significant (p < 0.05) decrease in S-100B in the blood on day 7 day after the TBI simulation compared with the group of the ”untreated” animals. This suggests less brain damage in these groups. In addition, in the described groups, the effect was statistically significantly (p < 0.05) superior to the effects of the same pharmacological agents in the groups with monotherapy (Fig.
A microscopic examination of the histological sections of the cerebral cortex after the TBI simulation showed clear signs of brain damage, which were accompanied by an increase in the cross section size of neurons and a decrease in the density of neurons and gliocytes (Table 3). The administration of the studied pharmacological agents as a monotherapy to the animals with TBI led to a statistically significant (p < 0.05) improvement in their morphometric parameters on day 7 day after the TBI simulation compared with the group of the ”untreated” animals and a positive dynamics of the visually evaluated histologic pattern. This suggests less brain damage in these groups, but the target level was not reached.
On day 7 in the groups administered with the studied combinations, the morphometric parameters were at the level of the intact animals. In the group with the combined administration of trimetazidine and citicoline, an increase in the neuron and gliocyte density significantly exceeds that in the groups of animals administered with the same pharmacological agents as a monotherapy (p < 0.05).
Thus, the results of the experiments indicate the most pronounced positive dynamics under the influence of the combined administration of trimetazidine and a new EPOR/CD131 heteroreceptor agonist EP-11-1 with citicoline, as well as their combinations in TBI. This is evidenced by the more pronounced effects of the combinations on the correction of morphofunctional disorders in simulated TBI compared to the effects of the same pharmacological agents used as a monotherapy.
Primary injury in TBI is accompanied by a number of disorders that trigger a cascade of destructive biochemical processes that lead to secondary injury of brain cells.
The main causes of secondary damage include: increasing edema, hematoma extension, secondary thrombosis, etc. They lead to the development of energy deficiency, excitotoxicity, oxidative stress, lipid peroxidation, neuroinflammation, inhibitory neurotransmitters deficiency, and apoptosis of the brain tissue cells (
Administration of the studied pharmacological agents as a monotherapy led to the correction of morphofunctional disorders occurring in simulated TBI. The pronounced neuroprotective activity of a new EPOR/CD131 heteroreceptor agonist EP-11-1 is partially mediated by EPOR/CD131. Autophosphorylation of Janus 2 (Jak2) kinase activates three main cascades. First, this is a transcription pathway that includes STAT3 and STAT5, which leads to amplified signals of survival and resistance to apoptosis (
Antiplatelet activity of EP-11-1 facilitates the modulation of the processes of release/absorption of such neurotransmitters as glutamate and GABA. At the same time, a decrease in the release of glutamate and the absorption of GABA by platelets occurs, which reduces the excitotoxicity (
The positive effects of trimetazidine can be associated with the activation of mitochondrial and cytoplasmic σ1 receptors and the inhibition of 3-ketoacyl-CoA thiolase. This leads to a decrease in the calcium intake to the cell and its mobilization from the intracellular depot. This prevents an increase in Ca2+ inside the cell, the release of glutamate, and, in part, prevents the development of excitotoxicity. The prevention of mitochondrial Ca2+ overload prevents energy starvation, inhibits the mitochondrial macropore opening, activation of caspases and the start of apoptosis (
The positive effects of citicoline in the combined administration of the studied pharmacological agents on the correction of morphofunctional disorders in TBI are realized due to its complex neuroprotective effect. Citicoline inhibits phospholipase A2. This mechanism leads to inhibition of the membrane phospholipids cleavage and the formation of arachidonic acid. On the one hand, this increases the stability of biological membranes; on the other hand, it reduces the neuroinflammation and the formation of reactive oxygen species. Ultimately, this helps to reduce apoptosis. There is experimental evidence that the anti-apoptotic effect of citicoline is realized by mitochondrial mechanisms, as well as by the increased expression of anti-apoptotic protein Bcl-2 (
Thus, in conclusion, it should be noted that the most pronounced positive neuroprotective effect observed for the combined administration of the studied pharmacological agents is explained by their influence on various pathogenic points of the development of secondary injury in TBI.
The authors declare no conflict of interests.
Oleg V. Antsiferov, Research assistant of the Department of Pharmacology and Clinical Pharmacology, Belgorod State National Research University. ORCID ID http://orcid.org/0000-0001-6439-2419, e-mail: oanciferov@yandex.ru. The administration of the drugs to the animals, modeling a TBI, and the development of the research design.
Roman F. Cherevatenko, Research assistant of the Department of Pharmacology and Clinical Pharmacology, Belgorod State National Research University. ORCID ID http://orcid.org/0000-0001-9707-9699, e-mail: ectomia@list.ru. The administration of drugs to the animals, modeling a TBI, and the development of the research design.
Mikhail V. Korokin, Doctor Habil. of Medical Sciences, Associate Professor, Professor of the Department of Pharmacology and Clinical Pharmacology, Belgorod State National Research University. ORCID ID http://orcid.org/0000-0001-5402-0697, e-mail: mkorokin@mail.ru. Writing the article, the development of the research design, sample preparation for the histological study, and a morphological description of aortic wall sections.
Vladimir V. Gureev, Doctor Habil. of Medical Sciences, Associate Professor, Professor of the Department of Pharmacology and Clinical Pharmacology, Belgorod State National Research University. ORCID ID http://orcid.org/0000-0003-1433-1225, e-mail: produmen@mail.ru. Consultation on planning, methodology and implementation of the experiment.
Anastasia V. Gureeva, 4-year student, Faculty of Medicine, Kursk State Medical University. ORCID ID http://orcid.org/0000-00031719-7316, e-mail: nastasyi.207@gmail.com. The administration of the drugs to the animals and modeling a TBI.
Marija A. Zatolokina, Doctor Habil. of Medical Sciences, Assistant Professor, Professor of the Department of Histology, Embryology, Cytology, Kursk State Medical University. ORCID ID http://orcid.org/0000-0002-9553-1597, e-mail: ZatolokinaMA@kursksmu.net. Writing the article, the development of the research design, sample preparation for the histological study, and a morphological description of aortic wall sections.
Elena V. Avdeyeva, Doctor Habil. of Biological Sciences, Professor of the Department of Normal Physiology, Kursk State Medical University. ORCID ID http://orcid.org/0000-0002-7152-5483, e-mail: avdeyeva_ev@mail.ru. Consultation on planning, methodology and implementation of the experiment.
Lyudmila A. Zhilinkova, PhD in Technical Sciences, Associate Professor, Department of Philosophy, Social, Legal and Natural Sciences, Kursk Academy of State and Municipal Service. ORCID ID http://orcid.org/0000-0003-0443-7130, e-mail: l_zhilinkova@mail.ru. Planning the experiments, analyzung the literature and interpreting the data.
Inga M. Kolesnik, PhD in Medicine, Associate Professor of the Department of Pharmacology and Clinical Pharmacology, Belgorod State National Research University. e-mail: kolesnik_inga@mail.ru. Planning the experiments, analyzing the literature and interpreting the data.