Volume 52, Nº 5 (2016)

The motion aftereffect may be considered as a consequence of visual illusions of self-motion (vection) and the persistence of sensory information processing. There is ample experimental evidence indicating a uniformity of mechanisms that underlie motion aftereffects in different modalities based on the principle of motion detectors. Currently, there is firm ground to believe that the motion aftereffect is intrinsic to all sensory systems involved in spatial orientation, that motion adaptation in one sensory system elicits changes in another one, and that such adaptation is of great adaptive importance for spatial orientation and motion of an organism. This review seeks to substantiate these ideas.

To study the effect of the onium atom nature on anticholinesterase efficiency, we tested elementorganic derivatives of tetramethylenbisonium compounds as reversible inhibitors of the following cholinesterases (ChE): acetyl-ChE from human erythrocytes, butyryl-ChE from horse serum, ChE from the brain of the grass frog Rana temporaria, ChEs from visual ganglia of the Pacific squid Todarodes pacificus, and ChE from visual ganglia of the commander squid Berryteuthis magister from different habitats in the Northwestern Pacific Ocean. Bisphosphonium inhibitors were found to be much stronger effectors than bisammonum compounds, although this may be due to a significantly increased size and hydrophobicity of their onium groups. Bisammonium organosilicon compound and its monoammonium analog were equally active as reversible ChE inhibitors in mammals. The first studied bis(phenyliodonium) derivative, which is characterized by a significantly increased hydrophobicity due to the introduction of fluorine atoms to the interonium tetramethylene chain, also exhibited a pronounced anticholinesterase effect on mammalian ChE.

Changes in electrical activity of the neocortex after prenatal hypoxia (day 14 of embryogenesis, E14, 7% O₂ for 3 h) and intracortical microinjection of epileptogenic 4-aminopyridine (4-AP) were studied in adult (3-month-old) rats. The frequency–time parameters of electrocorticogram (ECoG) were analyzed during sleep and wakefulness as well as in a model of 4-AP-induced spike-wave discharge (SWD) epileptiform activity. The results showed that in rats exposed to prenatal hypoxia the theta rhythm had a lower frequency while sleep spindles displayed a lower spectral power in the low-frequency range as compared to the control group. In rats with prenatal pathology, there was revealed a delayed onset of epileptiform activity and a shifted frequency distribution of the SWD spectral power induced by 4-AP.

In control experiments (n = 16), during direct stimulation of m. Soleus by trains of 5, 10 and 50 stimuli at a rate of 20 Hz a biphasic change was detected in the amplitude of the last contractile responses (LCR_N) depending on N, where N is the number of individual contractile responses in the tetanus. Thus, an initial decrease in LCR_N amplitudes (down to 54 ± 8% for LCR₅) was followed by a subsequent increase (up to 218 ± 14% for LCR₅₀) and significant shortening of their half-relaxation time compared to the initial response (down to 44 ± 8% for LCR₅₀). Caffeine at concentrations of 5 (n = 6) and 10 (n = 4) mM exacerbated LCR₅ depression (down to 31 ± 8% and 15 ± 4%, respectively) against the background of arising characteristic stationary contracture responses. The subsequent increase in the LCR_N amplitude was substantially lower than in control experiments (114 ± 18% and 46 ± 9% for LCR₅₀ compared to the initial response at 5 and 10 mM of caffeine, respectively). The LCR₅₀ half-relaxation time during the effect of caffeine at both concentrations also remained considerably shorter than that of individual responses recorded both in the presence of caffeine and in control experiments. In contrast to the control and caffeine effects, LCR₅ and LCR₁₀ amplitudes during the effect of 10 μM of dantrolene (n = 5) remained at the level close to that of the first response (102 ± 7% and 106 ± 8%, respectively), while the LCR₅₀ amplitude displayed a considerably smaller increase (to 143 ± 14%) than observed in control muscles. Besides, dantrolene further enhanced muscle relaxation at rest. Caffeine (10 mM), as applied in the presence of dantrolene, restored the dynamics of changes in amplitude–temporal characteristics of last contractile responses to values approximating those in control. The amplitude–temporal characteristics of action potentials recorded extracellularly in individual m. Soleus muscle fibers did not change significantly during the transition from single to train stimulation under the same protocol as in mechanographic experiments. These data may be interpreted in support of the previously advanced hypothesis on the implication of Ca²⁺-induced Ca²⁺ release in skeletal muscles under their tetanic stimulation as an additional mechanism of excitation–contraction coupling [1, 2].

Distribution of GABA and glycine immunoreactivity was studied in synapses on primary afferent axons of the lamprey Lampetra fluviatilis spinal cord using a double labelling technique. Approximately 25% of synapses exhibit GABA immunoreactivity, while more than 70% are immunoreactive to both neurotransmitters. As in other vertebrates, axo-axonal contacts represent three-component synaptic complexes, the so-called triads, where the immunoreactive terminal make synaptic contact simultaneously with the afferent axon and the dendrite contacting this afferent. Contact zones with gap junction-like cell membrane specializations were found between adjacent afferents suggesting the presence of electrotonic interaction between them. This interaction appears to serve for the synchronization of the afferent flow and represents a structural correlate of the mechanism of rapid interneuronal communication between functionally uniform neurons, which is an important element in the organization of coordinated locomotor acts. Besides, our studies provide evidence that afferent–afferent interaction may be mediated not only electrotonically but also with the aid of chemical synapses. This finding suggests that glutamate-induced depolarization of primary afferents results not only from autoreception but also from the direct effect of glutamate on the afferent’s cell membrane.

Coevolution is the interaction in the process of evolution of different species that are closely related biologically but do not exchange genetic information. In this paper, we address the problem of coevolution of the whole organism’s physiological systems as a process of the interrelated development of structure and function as well as their regulatory systems during the formation of living organisms. We consider the coevolution of osmoregulation and the nitrogen metabolism type, systemic and individual coevolutionary strategies of cell volume regulation in poikiloosmotic and homoiosmotic animals, coevolution of effectory organs and endocrine factors in the development of water–salt homeostasis, co-involvement of neurohypophyseal nonapeptides and glucagon-like peptide-1 in the regulation of the renal function aimed at stabilizing physico-chemical parameters of extracellular fluids which make up the internal environment of the organism.

On page 54, right column, the final line of the text should read: Supported by the RSF grant no. 15-15-20008.

On page 214, left column, the final paragraph of the text should read: Supported by the RSF grant no. 14-15-00413. Spectrophotometric studies were carried out at the Center for Collective Usage of Scientific Equipment, Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences.

On page 258, right column, the final line of the ACKNOWLEDGMENTS should read: The study was financially supported by the Russian Scientific Foundation (project no. 15-14-10014).