Mammalian Target of Rapamycin (mTOR) Inhibitor Improves Local Immune Microenvironment and Reduces Seizures via Increasing miR-211 Level in Rat Brain

This study aims to analyze the role of mTOR inhibitor on the expression of miR-211 in rat brain tissue and the biological effect of miR-211 in attenuating seizure. Rats were randomly divided into four groups, and the number of seizures and the duration of single seizure were observed within 24 hours after intervention. The level of miR-211 in brain tissue was detected by RT qPCR, the apoptosis of nerve cells was assessed by TUNEL staining, the level of immune cells was detected by flow cytometry, and the level of serum inflammatory factors was determined by ELISA. The number of seizures and the duration of single seizure in the three groups treated by rapamycin within 24 hours were lower than those in the control group, and the symptom relief in group C was the best. After treatment, the expression level of miR-211 in the brain tissue of epileptic rats increased. TUNEL staining showed that neuronal apoptosis was obvious in epileptic rats. The anti apoptotic ability of group C was the most significant, followed by group D and group B. Compared with group A, the levels of CD3+ cells, CD8+ cells and CD4+/CD25+ cells in brain tissue of group C were decreased, while the levels of IL-2 and IFN-γ were lower in group C than those in control. In group C (n = 5), the levels of CD3+ cells, CD8+ cells and CD4+/CD25+ cells were elevated, and the levels of immune related cytokines IL-2 and IFN-γ were higher than those of rats without miR-211 inhibition. mTOR inhibitors can improve the local immune microenvironment, reduce the release of inflammatory factors, and finally decrease the frequency and duration of seizures by up regulating the level of miR-211 in rat brain tissue.

5-aminolevulinic acid-induced accumulation of protoporphyrin IX in rat brain tissue

The aim of the study was to compare the level of accumulation of protoporphyrin IX (ППIX) in the brain of rats in normal conditions and in experimental C6 glioma. Materials and methods. In an experiment on 15 rats, one group of animals (n=5) was intracranially implanted with rat glioma of the C6 line. 14 days after tumor implantation, the animals were injected into the lateral vein of the tail with a photosensitizer — a preparation of 5-aminolevulinic acid (5-ALA) Alasens at a dose of 100 mg / kg. Another group consisted of 5 intact rats, which were also injected with Alasens. The rats were euthanized 4–5 hours after the injection of the photosensitizer, and fluorescent metabolic navigation was performed with illumination of the brain with light with wavelengths of 417 and 435 nm. For objectification, fluorescence biospectroscopy was performed. Similar manipulations were performed with animals of another group (n=5) — intact rats that did not receive Alasens. Results. In contrast to humans, in rats, the 5-ALA metabolite — PPIX accumulates in healthy brain tissue, while the fluorescence intensity does not differ from that visualized in the tumor area. It was also noted that the light of the blue spectrum promotes weak fluorescence of the white matter of the rat brain in the absence of exogenous 5-ALA, which can potentially be explained by the activation of endogenous PPIX or other fluorophores. Conclusion. After the administration of Alasens (5-ALA preparation), the accumulation of PPIX by the rat brain tissue occurs not only by malignant cells, but also by normal brain tissue without signs of malignancy or other pathological changes. A more thorough study of this phenomenon is required, since significant differences in the metabolism of 5-ALA in humans and laboratory animals will call into question the correctness of translation of experimental results into clinical practice.

THE EFFECT OF NERVE GROWTH FACTOR ON INDICATORS OF THE ANTIOXIDANT SYSTEM IN RAT BRAIN TISSUE

The work was to study the effect of nerve growth factor (NGF) on the parameters of the antioxidant system in the rat brain. From the submandibular salivary glands of male mice, we isolated and purified fractions with nerve growth activity. We study the effect of NGF on the parameters of the antioxidant system – catalase, superoxide dismutase (SOD), and malon dialdehyde (MDA). It was found that the activity of catalase increases at a concentration of NGF of 5 μg, with a further growth of concentration of NGF a decrease in the activity of the enzyme was observed. SOD activity tends to increase at NGF concentrations of 5 and 25 μg. The decrease in the content of MDA is pronounced with the introduction of various concentrations of NGF. Thus, the activity of antioxidant enzymes tends to be restored in the presence of NGF. Neuroprotectors can exhibit therapeutic efficacy of antioxidants in neurodegenerative diseases and ischemic brain damage.

GM3 Ganglioside Linked to Neurofibrillary Pathology in a Transgenic Rat Model for Tauopathy

Glycosphingolipids (GSLs) are amphipathic lipids composed of a sphingoid base and a fatty acyl attached to a saccharide moiety. GSLs play an important role in signal transduction, directing proteins within the membrane, cell recognition, and modulation of cell adhesion. Gangliosides and sulfatides belong to a group of acidic GSLs, and numerous studies report their involvement in neurodevelopment, aging, and neurodegeneration. In this study, we used an approach based on hydrophilic interaction liquid chromatography (HILIC) coupled to high-resolution tandem mass spectrometry (HRMS/MS) to characterize the glycosphingolipid profile in rat brain tissue. Then, we screened characterized lipids aiming to identify changes in glycosphingolipid profiles in the normal aging process and tau pathology. Thorough screening of acidic glycosphingolipids in rat brain tissue revealed 117 ganglioside and 36 sulfatide species. Moreover, we found two ganglioside subclasses that were not previously characterized—GT1b-Ac2 and GQ1b-Ac2. The semi-targeted screening revealed significant changes in the levels of sulfatides and GM1a gangliosides during the aging process. In the transgenic SHR24 rat model for tauopathies, we found elevated levels of GM3 gangliosides which may indicate a higher rate of apoptotic processes.

Neuroprotective and cerebrovascular effects of endogenous N-Arachidonoyl-GABA and its putative Cox-2 metabolite – GABA conjugate with Prostaglandin E2

Introduction: The aim of the study was to compare the neuroprotective and cerebrovascular effects of bioactive, endogenous lipid – N-arachidonoyl-GABA (AA-GABA) and GABA conjugate with prostaglandin E2 (PGE2-GABA) by evaluation of a morphological state of rat brain tissue and lipofuscin levels under the condition of permanent focal brain ischemia, as well as cerebral circulation under the condition of global transient ischemia. Materials and methods: The study has been implemented using the models of the left middle cerebral artery occlusion (MCAO) and global transient ischemia of the brain. A morphological examination of the brain tissue, a registration of local blood flow by laser flowmeter, and quantitative measurement of lipofuscin by fluorescence spectroscopy were used. Results and discussion: AA-GABA and the putative COX-2 metabolite PGE2-GABA showed significant neuroprotective and cerebrovascular effects in rat models of global and focal cerebral ischemia. In the MCAO model, AA-GABA and PGE2-GABA at a dose of 2 mg/kg/day administered i.p. for 6 or 12 days led to: 1) significant restoration of neurons and glial cells with intracellular regeneration of cytoplasmic and nuclear structures, 2) decrease in brain tissue edema; 3) attenuated thrombosis and stasis, and 4) absence of large necrotic foci in rat brain tissue. AA-GABA and PGE2-GABA at the same dose prevented excessive accumulation of lipofuscin in both brain hemispheres in rats with MCAO. All the studied compounds increase cerebral blood circulation in rats subjected to global transient ischemia. However, the cerebrovascular effect of PGE2-GABA was superior to the activity of AA-GABA and all other tested compounds. AA-GABA and PGE2-GABA, unlike PGE2 and nimodipine, increase the cerebral blood flow in rats with global transient brain ischemia and have no influence on the intact animals. Apparently, the GABAergic vascular system of the brain is involved in the mechanisms of the neuroprotective action of AA-GABA and PGE2-GABA. Conclusion: For the first time, we demonstrated the ability of AA-GABA and its putative metabolite COX-2 PGE2-GABA to improve cerebral circulation, attenuate structural damage and lipofuscin accumulation during cerebral ischemia. The natural origin of AA-GABA, which possesses neuroprotective and cerebrovascular activity, as well as anti-aggregatory activity, allows considering AA-GABA as one of the endogenous protective factors in ischemic brain lesions. Graphical abstract: