Zhurnal evoliutsionnoi biokhimii i fiziologii最新文献

Quantum analysis of postsynaptic currents is important for fundamental and applied studies of synaptic transmission. In the present work, we investigated the possibility of using the characteristics of spontaneous excitatory postsynaptic currents (EPSCs) for estimation of quantum parameters of excitatory synaptic transmission in different types of neurons from rat prefrontal cortex slices. By blocking spontaneous spiking activity in slices by tetrodotoxin, we showed that spontaneous and miniature EPSCs in prefrontal cortex neurons did not differ by their properties. Thereby, both spontaneous and miniature responses can be used for estimation of quantum parameters of excitatory synaptic transmission in this preparation. We also revealed that excitatory spontaneous responses of pyramidal cells were 2 times lower by amplitude, had twice lower the coefficient of variation and exhibited much slower kinetics than responses of the fast-spiking and regular-spiking interneurons. Possible mechanisms of these differences are considered.

Effects of neurohypophysial nonapeptides of vertebrates (vasopressin, vasotocin, and their synthetized analogues) on urinary magnesium excretion were studied in rats. Neurohypophysial hormones and their analogues at doses stimulating V2-receptors (0.0001-0.001 nmol/100 g BW) produced antidiuretic effect and reduced urinary magnesium excretion. At the higher doses activating V2- and V1a-receptors (0.025-0.1 nmol/100g BW), vasotocin and its analogues (deamino-vasotocin (dAVT), deamino-Thr4-vasotocin, deamino-hArg8-vasotocin, deaminomonocarbo-vasotocin) enhanced excretion of magnesium and sodium ions. Direct relation between increase in renal excretion of sodium and magnesium ions was found under these conditions. dAVT induced 10 times lesser increase in magnesium excretion after administration of a V1a-receptor antagonist. An antagonist of V2-receptors did not affect the dAVT-induced magniuresis. The obtained data suggest that V-receptors take part in regulation of magnesium transport in rat kidney.

The absorption of yellow fluorescent protein (YFP) and the expression of the endocytic receptors, megalin and cubilin, were investigated in the renal proximal tubules (PT) in frogs Rana temporaria after parenteral YFP injections. The methods of confocal microscopy and immunohistochemistry were used. The dynamics of YFP absorption was analyzed 2 h after injection. The logarithmic time dependence of the accumulation of YFP-containing endocytic vesicles in PT cells and the completion of absorption process 90-120 min after injection were shown. Unlike substantial megalin and cubilin expression 15-30 min after YFP introduction, immunolabeled endocytic receptors were not detected in PT cells after 2 h. The re-injection of YFP led to the appearance of apical endocytic vesicles containing megalin or cubilin colocalized with YFP. At the same time, the decrease of YFP uptake associated with reduction in the number of receptor-containing vesicles was demonstrated, suggesting a failure of megalin and cubilin expression. The decrease of absorption capacity of PT cells after YFP re-injection was similar to that found previously under conditions of the competitive absorption of green fluorescent protein (GFP) and YFP injected in different sequences. The data are the further demonstration of the proposed mechanism limiting the tubular protein absorption in the frog kidney and suggest the involvement of megalin and cubilin in uptake and vesicular transport of YFP.

There are considered reactions of male Wistar rat blood system to repeated action of nitrogen-oxygen hyperbaria (pressure 0.5 MPa, density of gas medium 6 g/l, pO2 = 0.02-0.03 MPa). Rats were placed into a barochamber for 5 h 24, 72, and 120 h after the first exposition (control in air without the increased pressure). Parameters of red blood were studied and the general state of the animals was estimated. It has been established that after the first hyperbaria séance the stress-reaction develops in rats with all objective stress parameters (level of corticosteroids and content of ascorbic acid in adrenals). At repeated exposure after 24 h the almost complete normalization of all stress parameters was observed, except for the increased hemoglobin content in plasma as a result of impair of permeability of erythrocytic membranes. After repeated actions 72 and 120 h later, the stress parameters manifested again. After exposure 120 h later, the general state of animals was sharply deteriorated they did not move in the "open" field, could not be hold on a horizontal bar, and mainly were lying. The performed control with the immobilization stress showed that after the initial stress-reaction the rats were recovered completely and at repeated exposures no changes were observed in the blood system and in the general state of the animals. We belive that the hyperbaria-produced stress is connected with difficult breathing under pressure. Thereby, the repeated action of hyperbaria is a harmful factor and habituation to it does not occur.

At present there are serious grounds to believe that motion aftereffect is characteristic for all sensory systems involved in spatial orientation, and that adaptation to movement in one sensory system causes changes in another one and that such adjustment is of critical adaptive significance. In this part of the review there are briefly presented developments and the current state of studies on this issue in visual modality. The visual motion aftereffect has been studied considerably more completely as compared with other modalities. The main concepts about mechanisms of this phenomenon and employment of adaptation to motion in studies of visual analysis of movement at its different levels are actively used in the current scientific literature to understand mechanisms of this phenomenon in other sensory systems. The leading role of vision for orientation in space is manifested in the multimodal interaction where visual adaptation to movement produces significant changes of perception in other modalities.

The review considers role of Ca2+ ions in regulation of specialized functions of cardiomyocytes (CM) in disturbances of heart activity. Problems of Ca(2+)-dependent signaling mechanisms leading to pathological hypertrophy, arrythmogenesis, and heart failure are elucidated. A particular attention is paid to analysis of Ca(2+)-dependent molecular mechanisms leading to remodeling of contractile proteins, apoptosis, or pathological growth of CM.

Animal models of epilepsy are very diverse and are used to elucidate the mechanisms underlying epileptogenesis and seizures. A single administration of pentylenetetrazole (PTZ) induces seizures, however it does not increase risk of further development of epilepsy. Pilocarpine immediately after injection evokes status epilepticus and after a latent period spontaneous convulsions develop in animals, i. e., the drug initiates the process of epileptogenesis. Assuming that in the PTZ model morphofunctional changes are mainly transient whereas changes in the lithium-pilocarpine (PC) model can indicate development of the brain epileptizationm, we compared morphological and functional characteristics in field CA1 of the hippocampus in a control and two groups of experimental animals 24 h after administration of convulsants. We revealed changes specific to the PC model and indicating the process of neurodegeneration: a decrease of the cell density, an altered NeuN expression, and an increase of the proapoptotic protease caspase-3 activity. A characteristic feature of the PTZ model was appearance of hyperchromic neurons with normal viability. In both models expression of the excitatory amino acids carrier EAAT1 increased by about 40% as compared to control. These morphofunctional correlates of reversible changes in the nervous tissue, caused by the convulsive state, and the early disturbances leading to the long-term brain epileptization can be used as indicators for evaluating therapeutic potential of novel anticonvulsive drugs.

At present, in ecotoxicological studies, as biomarkers there are used physiological reactions of invertebrates, based on diverse reflex. The primary chain of the reflex is chemo-, mechano-, and osmoreceptors. The structures are exposed on the surface of body and mantle cavity. Earlier, a hypothesis was put forward, which suggested that the polymodal osphradial organ of the pond snail might participate in adaptive reactions of aquatic molluscs to toxicants. The known homology of osphradial structures allows spreading this suggestion on marine representatives of various subclasses of Mollusca, although diversity of structure, of ways of nutrition, and multiplicity of aquatic molluscs can impede interpretation of future ecotoxicological studies. To elucidate this issue, we carried out the comparative electron microscopy study of osphradial organs in representatives of various families of Prosobranchia (Mollusca, Gastropoda). By ultrastructural parameters in the osphradial organs, five sensory cellular complexes (SCC) have been revealed. A probable connection is demonstrated of these cellular complexes with the known chemo-, mechano-, and osmoreceptor modalities. Structure of the complexes become more complicated in the process of evolution of gastropods and depends on the way of nutrition of molluscs. Thus, the primitively built osphradium of the herbivorous mollusc Viviparus sp. is a polymodal receptor and initial prototype for further morphophysiological constructions. Osphradium of littorine is the next chain of evolitionary transformations and combines in itself the osmo- and chemosensory SCC. In osphradia of the new, ctenidial type the total receptor surface increases and the ultrastructural specialization of cellular complexes occurs, which promotes the appearance in them of the sarcophagous way of nutrition. For predator marine molluscs actively searching for their preys by odor, there is identified an additional superficial sensory cellular complex. It is located on lateral surfaces and on ventral edge of petals of osphradia, near zones of cilium supportive cells. These seem to be mechanoreceptor structures tracing direction and rate of flow of liquid along osphradium. A connection of SCC with the certain modality of outer nutrition and with the way of nutrition is suggested.

The role of disturbances in the hormonal signaling systems of brain and peripheral tissues in etiology and pathogenesis of diabetes mellitus (DM) of the types 1 and 2 is discussed. Available data confirming the hypothesis of central genesis of some forms of DM caused by disturbances in the brain neurotransmitter systems are presented. It is concluded that the study of disturbances in the hormonal signaling systems is a promising approach for development of new strategies of DM treatment, based on correction of these disturbances in the CNS and the periphery.