Vol 55, No 2 (2019)

The review addresses the features of the establishment of respiratory activity in the ancient taxa, cyclostomes and fish, which allowed them to adapt to aquatic habitats with a low oxygen level. The brainstem of cyclostomes and fish contains a basic set of nuclei that provides the formation of adequate respiratory activity. The latter is mediated by the universal excitatory and inhibitory neurotransmitters (glutamate, GABA, glycine), suggesting the existence of pivotal, evolutionarily conserved mechanisms to reproduce respiratory oscillations. The qualities of water as a habitat with a reduced oxygen tension determine a high significance of branchial and extrabranchial oxygen-sensitive chemoreceptors which share similar features with highly specialized mammalian oxygen receptors. Neurophysiological details of the respiratory rhythm generator machinery as well as peculiarities of respiratory adaptation to fluctuations in water oxygen tension (PwO₂) in agnathans (cyclostomes) and gnathostome fish support the concept of a close relationship between the evolutionarily “verified” adaptive mechanisms regardless of the level of organization of individual vertebrate classes.

The goal of the study was to demonstrate the ability of fluoride ions (F⁻) to activate key components of the receptor-dependent apoptotic pathway, membrane Fas receptors, caspase-8 and caspase-3, in rat erythrocytes in vitro. Cells were incubated in the presence of increasing NaF concentrations (0.1–10 mM) for 1, 5 and 24 h. Caspase-8 and caspase-3 activities were assayed by flow cytometry, expression of Fas receptors by immunoblotting. It was found that the kinetics of stimulation of Fas receptors, caspases-8 and caspases-3 in rat erythrocytes by fluoride ions differs depending both on the fluoride concentration and exposure time. For instance, activation of caspases was observed as early as 1 h after incubation with fluoride, while treatment of erythrocytes with 5 mM NaF for 24 h increased the cell population with active caspases-8 and caspases-3 up to ca 15-16%. At the same time, expression of Fas receptors increased in a concentration-dependent manner only after 24 h of incubation with NaF. Thus, one of the mechanisms underlying premature death of rat erythrocytes induced by fluoride in vitro is the ability of the latter to stimulate messengers of the receptor-dependent apoptotic pathway. However, it is possible that caspase-8 and caspase-3 activation is, at least in part, independent of the membrane-associated mechanism of activation of Fas receptors.

The long-term effects of acute organophosphate (OP) poisoning remain poorly studied, while experimental models usually disregard species-related specificity of rodents as model objects. Here we present two toxicological models and a comparative analysis of a wide range of biochemical blood indices in their dynamics over 3 months after acute rat poisoning with paraoxon. As expected, the most sensitive biochemical index within the first hours and days after OP poisoning was whole blood acetylcholinesterase activity, which decreased by almost an order of magnitude in all experimental groups 3 h after poisoning. Changes in the parameters of carbohydrate and fat metabolism (triglyceride, free fatty acid, D-3-hydroxybutyrate, cholesterol and glycerol levels) were detected in experimental groups at different time points after poisoning. Statistically significant changes in a number of biochemical markers were found in positive control rats relative to intact rodents.

We report a comparative analysis of the effect of alpha- and beta- isomers of the dipeptides aspartyl-serine and aspartyl-proline on the ability of honeybees to retain the conditioned food reflex to olfactory cues in their short-term/long-term memory. Stimulatory/inhibitory effects of the alpha-dipeptides on memory processes are confined to the concentration range of 10^-6–10^-8 M. In contrast, beta-dipeptides exert stimulatory/inhibitory effects on memory not only within the same range but also at ultra-low (pico- and femtomolar) concentrations. At concentrations of 10^-9–10^-11 M, beta-dipeptides have no effect on the characteristics under study (“silence zone”). Thus, we revealed fundamental differences in the effects of alpha- and beta- dipeptide isomers on the memory regulation.

Liquor-contacting cells, immunoreactive to oxytocin, vasopressin, monoamines (dopamine, serotonin) and calbindin, were found in hypothalamic neurosecretory nuclei of turtles (Testudo horsfieldi and Emys orbicularis). They are considered as sources of the nonsynaptic transventricular pathway responsible for the delivery of a broad variety of hormones and neuromodulators to different hypothalamic and extrahypothalamic brain structures. This phylogenetically ancient tract is inherent to all vertebrates, including humans, and contributes to the organization of different forms of social behavior.