A study of the infrared spectrum of the environment of the planetary nebula Tc 1 revealed the radiation of cold and neutral fullerenes C60 and C70. The results of the analysis of infrared spectra obtained using the Hubble space telescope conclusively proved the existence of C60+ fullerene in the interstellar medium. These large carbon-containing molecules can form and exist in the interstellar medium and are candidates to explain many diffuse interstellar absorption bands. In this study, the potential neuroactivity of the C60 fullerene as a planetary dust component was assessed in the isolated rat brain nerve terminals. It was shown that C60 fullerene in the unirradiated state at concentrations of 0.05-0.25 mg/ml did not change the extracellular levels of excitatory neurotransmitter L-[14C]glutamate and inhibitory neurotransmitter [3H]GABA in the preparations of rat brain nerve terminals. An increase in fullerene C60 concentrations up to 0.5 and 1.00 mg/ml was accompanied by an increase in the extracellular levels of L-[14C]glutamate and [3H]GABA in the preparations of nerve terminals. Therefore, fullerene C60 did not cause signs of acute neurotoxicity in the brain nerve terminals within the concentration range of 0.05-0.25 mg/ml. However, given that C60 undergoes photooxidation, it can be expected that it may acquire neurotoxic properties in situ.

The study aimed to develop a strategy and methodology for neuroprotection during long-term space missions, which is based on a comprehensive study of the impact of therapeutic hypothermia combined with the action of neuroactive drugs on the key characteristics of synaptic transmission in brain nerve terminals, which change under the influence of planetary dust and conditions of altered gravity. Development of neurotoxicity under conditions of altered gravity may result from excess extracellular glutamate caused by the reverse functioning of glutamate transporters. Under conditions of moderate and deep hypothermia, a gradual decrease in the transporter-mediated release of L-[14C]glutamate from nerve terminals was demonstrated, which is stimulated by plasma membrane depolarization with KCl and dissipation of the proton gradient of synaptic vesicles by the protonophore FCCP. This fact indicates a neuroprotective effect, which increases when hypothermia changes from moderate to deep. The possible risks of using hypothermia in space medicine have been determined. Hypothermia is not able to reduce the extracellular level of L-[14C]glutamate and [3H]GABA, which increases under the conditions of exposure to carbon-containing planetary dust. Hypothermia can lead to a further decrease in the rate of accumulation of neurotransmitters in the presence of carbon-containing planetary dust and to contribute to the development of neurotoxicity, which is a possible risk of using hypothermia in space medicine. In this context, it is important to choose the optimal individual temperature regime for each astronaut.

Carbon is widely distributed in the Martian dust, meteorites and interstellar space. In this study, we prepared carbon-containing Martian dust analogue, which consists of inorganic Martian dust simulant derived from volcanic ash (JSC, Mars1A, ORBITEC, USA) and carbon (nanodiamonds). The aim of the study was to analyze the effects of carbon-containing Martian dust analogue on the key characteristics of the synaptic neurotransmission. It was shown that the carbon-containing Martian dust analogue enriched with nanodiamonds significantly reduced the initial rate of accumulation and increased extracellular levels of neurotransmitters L-[C-14] glutamate and [H-3] GABA (gamma-aminobutyric acid) in isolated rat brain nerve terminals. These effects of carbon-containing Martian dust analogue were mainly associated to the activity of its carbon component, but not to inorganic components. So, carbon component of native Martian dust can have deleterious effects on extracellular glutamate and GABA homeostasis in the CNS, and so glutamate-and GABA-ergic neurtransmission, disballansing exitatory and inhibitory signals. Thus, the toxic effects of carbon structures in native Martian dust, soil, and meteorites for human health may be greater than the effect of the inorganic components.

An amperometric glutamate biosensor was developed and adapted for analysis of velocity of glutamate uptake by isolated nerve terminals of rat’s brain. Glutamate oxidase was used for creation of biomembrane of the biosensor; the enzyme was co-immobilized with bovine serum albumin via glutaraldehyde on the surface of platinum disc electrode. Additional semi-permeable membrane based on phenylenediamine was placed onto the surface of the electrode for improvement of selectivity of the biosensor. Conditions for the enzyme immobilization onto the surface of working electrode were optimized (dependence of the biosensor work on concentrations of the enzyme and glutaraldehyde, as well as immobilization time were studied). The influence of parameters of working buffer (ionic strength, buffer capacity, pH) on the biosensor work was investigated. Linear range of the biosensor was 2-600 µM of glutamate, limit of glutamate detection was 0.5-2 µM, sensitivity was 250-300 nA/ mM. The biosensor was characterized by good reproducibility of responses and operational stability. The presence of endogenous glutamate in preparations of isolated nerve terminals of brain was shown by using the biosensor. It was demonstrated that the initial rate of Na-dependent glutamate uptake and accumulation by the nerve terminals measured by the biosensor were not significantly different from the results obtained by using radioactive-labeled L-[14C] glutamate. The described work will allow wide usage of the developed biosensor in medicine, as well as in biotechnological and biochemical studies.

The effects of highly-selective blocker of γ-aminobutyric acid transporters of GAT1, NO-711, and substrate inhibitor of γ aminobutyric acid transporters GAT3, ß-alanine on the initial velocity of L-[14C]glutamate and [3H]-γ-aminobutyric acid uptake by cortical, hippocampal and thalamic nerve terminals (synaptosomes) were analyzed in norm and after perinatal hypoxia. Rats were underwent to hypoxia and seizures (airtight chamber, 4% O2 and 96% N2) at the age of 10–12 postnatal days. The experiments were performed at 8–9 weeks in the control and after hypoxia. It was shown that NO-711 (30 microM) and ß-alanine (100 microM) did not affect initial velocity of L-[14C] glutamate uptake by cortical, hippocampal and thalamic synaptosomes. In cortical synaptosomes, NO-711 and ß-alanine decreased the initial velocity of [3H]-γ-aminobutyric acid uptake, but their inhibitory effects were similar in control and hypoxia groups. The effectiveness of ß-alanine to influence [3H]-γ-aminobutyric acid uptake was increased in hippocampal and thalamic nerve terminals as a result of perinatal hypoxia, whereas the capacity of NO-711 in thalamic nerve terminals was decreased. These results suggest changes in the ratio of active GAT1/GAT3 expressed in the plasma membrane of nerve terminals after perinatal hypoxia. Thus, ß-alanine is a promising substance for development of neurotropic pharmacological preparations for the transporter-mediated regulation of GABA-ergic neurotransmission.

During inhalation, nano-/microsized particles of lunar dust are efficiently deposited in nasal, tracheobronchial, and alveolar regions and transported to the central nervous system. The neurotoxic potential of lunar dust has not yet been assessed. The research was focused on the analysis of the effects of lunar dust analogue on the key characteristics of glutamatergic neurotransmission. Disturbances in glutamate homeostasis contribute to the pathogenesis of major neurological disorders. The average size of particles of lunar dust analogue (JSC- 1a, Lunar Soil Simulant, Orbitec, USA) before and after sonication was determined by dynamic light scattering. With the use of radiolabeled L-[C-14]glutamate, it was shown that there is an increase in L-[C-14]glutamate binding to isolated rat brain nerve terminals (synaptosomes) in low [Nal media in the presence of lunar dust analogue that led to an apparent increase in the initial velocity of L-C-14 Iglutamate uptake by 10% in control rats, and those underwent to gravitational overload. Thus, the unique effect of lunar dust analogue to increase glutamate binding to the nerve terminals was shown. This can have deleterious effects on the extracellular glutamate homeostasis in the central nervous system that is extremely important for proper synaptic transmission. During a long-term mission, a combination of constant irritation due to dust particles, inflammation, stress, low gravity and microgravity, radiation, UV, and so on may consequently change the effects of the dust and aggravate neurological consequences.