Том 55, № 1 (2019)

The review briefly summarizes information on the role of humoral factors as well as the nervous and endocrine systems in the regulation of fish feeding behavior with a major focus on neuropeptides. The influence of biogenic and abiogenic factors on the regulatory systems and the role of individual peptides and their interplay at different phases of fish feeding behavior are considered. An attempt is made to link our knowledge of feeding behavior of “wild” fish to the known mechanisms of its regulation.

We analyzed the role of serotonergic system in the protection of an organism of different animal species (mice, fish) from lethal doses of bacterial and chemical toxins. In the first series of experiments, peritonitis was induced in mice by i.p. administration of the pathogenic Escherichia coli strain, and the following i.m. administration of the serotonin-modulated anticonsolidation protein (SMAP) significantly increased their survival rate (75 vs. 30%, p < 0.05). In the second series, Western blot analysis showed that i.m. administration of SMAP to mice led after 5 h to a sharp upregulation of the 70 kDa heat shock protein (HSP70) in the liver. In the third series, carried out on the common carp Cyprinus carpio L., i.m. administration of SMAP prior to putting the fish into water containing a high concentration of a systemic insecticide Actara led to the survival of all individuals in the experimental group over the period of 5 days, whereas in the control (SMAP-free) group the survival rate over the same period was only 35% (p < 0.001). In the fourth series, administration of anti-SMAP polyclonal antibodies to C. carpio caused death of 75% of individuals that were put for 5 days into the water containing the sublethal Actara dose, whereas in the intact and control groups all individuals survived under the same conditions (p < 0.001).

The fatty acid composition of phospholipids was studied in rat erythrocytes after exhausting swimming. It was shown that this stressful exposure does not affect the fatty acid (FA) composition of erythrocyte phospholipids. However, differences in the variability of quantitatively dominant fatty acids were detected in stress-exposed animals compared to unstressed control. In saturated acids (C16:0, 18:0) and polyenoic arachidonic acid (C20:4ω6), the variability was close to its control values, while in unsaturated fatty acids (C18:1, C18:2ω6) it exceeded those 3–4 times. The obtained results indicate significant alterations in the unsaturated fatty acid composition of erythrocyte membrane phospholipids. Due to unsaturated fatty acids, a potential arises in the insulating layer between two surface charges of the erythrocyte plasma membrane. This additional internal potential, alongside with the potential difference between outer and inner surfaces of the erythrocyte plasma membrane, affects aqueous pores and Na⁺, K⁺-channels which jointly mediate diffusion of oxygen molecules. The revealed extraordinary variability of unsaturated fatty acids (C18:1, C18:2) with their mobile ω-electrons may relate to the mechanism of chemical interaction between phospholipid fatty acids in the hydrophobic zone of the erythrocyte plasma membrane due to phospholipid diffusion. Analogous mechanism of chemical interaction (via a proton jump from the hydronium ion to the water molecule) occurs in the hydrophilic (aqueous) zone.

The study was aimed at determining tissue antioxidant levels in three closely related albeit ecologically different Canidae species: the raccoon dog (Nyctereutes procyonoides), silver fox (Vulpes vulpes) and blue fox (Vulpes lagopus), aged 0.5 (juvenile), 1.5–3.5 (adult) and 4.5–5.5 (aging) years. Some tested parameters were found to be species-specific: as compared to other species, raccoon dogs and blue foxes exhibited higher α-tocopherol levels in the liver and kidney, blue foxes were characterized by a higher activity of the antioxidant enzymes in the kidneys, while silver foxes had higher glutathione (GSH) levels in the liver, kidneys and heart. The antioxidant defense system in all organs of the tested species was distinguished by a relative stability. In raccoon dogs, the retinol level in the heart increased with age, while in silver foxes it is only superoxide dismutase (SOD) activity in the kidneys and the GSH level in the liver and heart that underwent significant changes with age. In blue foxes, aging was accompanied by an increase in liver retinol and kidney α-tocopherol levels as well as a decrease in the kidney GSH level. Besides, sex differences were found in antioxidant levels in blue foxes. Our results are consistent with the data obtained by other authors for other animal species, indicating a mixed pattern of age-related changes in the antioxidant defense system of carnivorous canids. While some antioxidants rise and the other fall, the functionality of the whole system does not appear to be disturbed. Ecological and physiological features of different mammalian species may determine the adaptive potential of animals and affect the tested indicators of the antioxidant defense system during late postnatal ontogenesis.

The negative long-term effects of hypoxic exposure on postnatal day 2 (human incomplete pregnancy model) on behavior (open field test) and activity of the hypothalamic-pituitary-adrenal (HPA) axis were studied in pubertal rats together with the possibility of their correction by post-hypoxic administration of a GABA derivative salifen (an adduct of γ-amino-β-phenylbutyric acid and salicylic acid). It was shown that perinatal hypoxic exposure impairs the inhibitory mechanisms in the CNS as manifested in the absence of motor activity inhibition in the open field as well as in the enhanced and prolonged stress response of the HPA axis. Post-hypoxic administration of salifen (15 mg/kg) for 14 days restored efficiently the inhibitory processes except for persistently increased hormonal stress reactivity of the HPA axis. Possible mechanisms underlying the therapeutic effects of salifen are discussed.

Arginine-vasotocin (AVT) is a hormone common to most vertebrates except mammals where it is replaced by vasopressin. A study of the effect of both nonapeptides of the vasopressin family [AVT and arginine-vasopressin (AVP)] showed that in the rat kidney they are involved in the regulation of renal sodium and solute-free water reabsorption. These effects are mediated by different subtypes of V-receptors activated by different blood serum concentrations of the hormone. An immunoenzyme assay (ELISA) was proposed to determine AVT concentrations under almost complete inhibition of AVP secretion. When both hormones were administered at equal doses, AVT broke down slower and acted longer than AVP. A high metabolic rate of the nonapeptide in the blood is supposed to be an evolutionary advantage as a tool to upgrade the water-salt balance regulation. The importance of comparing the effects of hormones lost during the evolution of vertebrates as a method to study the evolution of functions is discussed.

1. On page 400. The name of the third author L. M. Gabitova should read D. M. Gabitova.

2. On page 400, in running head. The name of the third author L.M. Gabitova should read D.M. Gabitova.