Vol 110, No 6 (2024)

Barbering is a behaviorally induced alopecia (hair and whisker biting) often observed in laboratory mice and rats. The role of this behavior is actively discussed, in particular, its relationship with stress, aggression, grooming and aberrant stereotypic behavior. Understanding the nature of barbering and its content in the state of laboratory animals is an important factor to consider in experimental work. Here, we discuss recent data on the neurobiology and genetics of barbering, as well as its role in the behavior and central nervous system of rodents.

One of the complications of diabetes mellitus (DM) is diabetic cardiomyopathy (DCM), the molecular mechanisms of pathogenesis of which have not been fully studied. Previously, the involvement of Na⁺/K⁺-ATPase and components of the Ca²⁺ transport system in cardiomyocytes in the development of DCM was shown. The aim of the work was to study the expression and activity of Na⁺/K⁺-ATPase and Ca²⁺-ATPase (SERCA2) in the myocardium of male Wistar rats in a model of streptozotocin (STZ)-induced prediabetes and overt type 1 diabetes (T1DM). STZ was administered at once i. p. in dose of 30–35 mg/kg. Rats with glucose levels above 11 mM were considered diabetic (STZ-D1 group), and those with moderate hyperglycemia were considered prediabetic (STZ-preD1 group). The activity of Na⁺/K⁺-ATPase and Ca²⁺-ATPase was determined (by the rate of release of inorganic phosphate, Pi), and the expression of the genes α1- and α2-isoforms of Na⁺/K⁺-ATPase, SERCA2 and Kir6.1, Kv7.1 and Kv2.1 potassium channels. In the control (C) group, the activity of Mg²⁺-dependent ATPase (α1- and α2-isoforms of Na⁺/K⁺-ATPase), sensitive to 1 mM ouabain, was 6.03±0.6 mmol Pi/g/h. In the STZ-D1 and STZ-preD1 groups, Na⁺/K⁺-ATPase activity did not differ from group C. The level of gene expression of α1- and α2- subunits of Na⁺/K⁺-ATPase in the STZ-D1 group decreased by more than 45%, then both in the STZ-preD1 group increased by 64 and 81%, which may indicate a high sensitivity of expression to insulinopenia. The activity of Ca²⁺-ATPase and the expression of the SERCA2 gene did not differ between the groups – probably, the 4-week period after STZ administration is not sufficient for the development of Ca²⁺-ATPase deficiency in the rat heart. The level of expression of the genes of the potassium channel subtypes Kv2.1, Kir6.1 and Kv7.1 increased in the STZ-preD1 group, which may indicate a certain contribution of the studied potassium channel subtypes to the adaptation mechanism to moderate hyperglycemia.

A decrease in body temperature in homeothermic animals can cause a state of the body called hypothermic. It is accompanied by the development of a number of pathological processes, many of which are associated with mitochondrial dysfunction and the development of oxidative stress. In connection with the widespread introduction of hypothermia into medical practice, the question of the possibility of a regulatory influence on the proxidant-antioxidant status of mitochondria at low body temperatures remains relevant. In recent years, plant polyphenols, in particular dihydroquercetin (DHQ), have gained wide popularity as therapeutic agents with antioxidant and membrane protective effects. In this work, we investigated the effects of DHQ on the intensity of oxidative stress in rat liver mitochondria under moderate hypothermia. It was found that a course (5 days) oral administration of DHA at a dose of 100 mg/kg significantly reduces the levels of LPO and OMP products in the liver mitochondria of control rats, increasing the content of non-enzymatic components of the thiol-disulfide antioxidant system`s. DHQ effectively protects liver mitochondria from the development of oxidative stress during hypothermia, as evidenced by a significant decrease (and in some cases, complete normalization) in the levels of diene conjugates, MDA, Schiff bases and carbonyl groups in a group of animals subjected to hypothermia with prior administration of this polyphenol. At the same time, DHQ significantly increases the levels of glutathione and vitamin E, and also normalizes the content of thiol groups in mitochondrial proteins. In vitro, DHQ exhibits a dose-dependent antioxidant effect, suppressing OMB in mitochondria incubated in Fenton's medium (IC50 = 0.160 mg/ml).

The search for natural biologically active substances that have a neuroprotective effect on cerebral ischemia-reperfusion is one of the urgent problems of modern neuroscience and medicine. Intranasally administered insulin (IAI) has a pronounced restorative effect on various neurodegenerative diseases, but the mechanisms of its action and therapeutic effects in cerebral ischemia have not been studied well, including in type 2 diabetes mellitus (DM2), which increases the risk of cerebrovascular dysfunction. The aim of the work was to study the effect of IAI on metabolic parameters and inflammatory factors in male rats with DM2 subjected to the two-vessel ischemia and prolonged forebrain reperfusion, in comparison with non-diabetic animals. A long-term high-fat diet with an injection of a low dose of streptozotocin (25 mg/kg) to rats was used to induce DM2, and a model of the global forebrain two-vessel ischemia induced by occlusion of both common carotids with prolonged reperfusion (IR) for 7 days was used to study cerebral ischemia. Two hours after the end of ischemia, rats were treated with IAI at a dose of 0.5 or 2.0 IU/rat, after which the drug was administered in the same doses daily for 7 subsequent days. It was found that IAI prevents body weight loss in both nondiabetic and diabetic rats that underwent IR, and also increases the total cholesterol level and the proportion of epididymal fat in rats without DM2 after IR. In DM2 rats that underwent IR, IAI in the explored doses reduces the level of postprandial glucose and insulin content in the blood, which indicates an improvement of glucose tolerance, and also reduces the levels of inflammatory factors in the blood – C-reactive protein (at a dose of 0.5 IU/rat/day) and tumor necrosis factor-α (in a dose of 2 IU/rat/day), which reveals its anti-inflammatory potential. Thus, the course treatment with IAI after induction of cerebral ischemia followed by reperfusion leads to an improvement of metabolic parameters and weakens inflammatory reactions in rats with DM2, which may be in demand in the correction of ischemic stroke in patients with DM2.

Hyperproduction of mediators of LPS-induced inflammatory process (endotoxicosis, sepsis) initiates the development of acute respiratory failure (ARF), impaired gas exchange, progressive hypoxemia and hypercapnia, hypotension, respiratory arrest and death. Severe sepsis associated with hypoxemia remains the main cause of death, and therefore the development of methods to increase resistance to acute hypoxia in septic patients is an urgent task. The aim of the work was to study the effectiveness of preconditioning with short-term intermittent moderate hypoxia to increase tolerance to subsequent severe hypoxia in rats with LPS-induced endotoxicosis. The experiments were carried out on anesthetized and tracheostomated male Wistar rats. Endotoxicosis was modeled by administration of a lipopolysaccharide solution (Escherichia coli) in an amount of 7 mg/kg. To assess resistance to severe hypoxia, the rebreathing method of (RM) with a gradual decrease in oxygen in the rebreather from 21% to the onset of apnea was used. Hypoxic preconditioning (hypoxic training, HT) was also created by the method of RM in the mode of 3 cycles: reduction of the oxygen fraction in the rebreather to 12% – 3 min, 5 min – normoxia. 3 groups of animals were studied: I-control-NaCl, II–LPS, III–LPS+HT. The following parameters were recorded: external respiration, mean blood pressure (APm.), saturation (SpO₂), fraction of inhaled O₂, time of onset of apnea, the amount of spontaneous respiratory recovery (autoresuscitation) in the posthypoxic period. It was shown that the administration of LPS under normoxic conditions was accompanied by hyperventilation, hypoxemia and hypotension. The maximum deterioration in resistance to severe hypoxia was observed in rats with LPS, which was manifested by a decrease in APm, SpO2 and a decrease in the possibility of autoresuscitation after hypoxic apnea. The effect of HT prevented a decrease in blood pressure, SpO₂ increased by 1.4 times, survival increased by 2 times, which is comparable to the level of normoxia before the introduction of LPS. It is assumed that the effectiveness of hypoxic preconditioning is due to the inhibition of the inflammatory response.

WAG/Rij rats are a valid model of absence epilepsy and comorbid depression. We have previously shown that WAG/Rij rats have disturbances in the sleep-wake cycle and changes in the characteristics of sleep spindles. A negative correlation was also found between the number of spike-wave discharges (SWD) and the duration of rapid eye movement (REM) sleep. Clinical evidence suggests that the traditional antidepressants imipramine and fluoxetine are effective in suppressing symptoms of depression, but may have a negative impact on the sleep-wake cycle and comorbid epilepsy in patients. Our previous studies in WAG/Rij rats showed that imipramine, when administered chronically, increases the number of SWDs, while fluoxetine at the same dose reduces their number, although both antidepressants have a pronounced antidepressant effect. Comparison of the effects of the antidepressants imipramine and fluoxetine on the sleep-wake cycle and sleep spindles in WAG/Rij rats remains unstudied. The purpose of this work is to find out: 1) what effects do imipramine and fluoxetine have on the sleep-wake cycle and the characteristics of sleep spindles in WAG/Rij rats and 2) whether there are differences in their effects. To achieve this goal, the characteristics of the sleep-wake cycle and sleep spindles were compared in WAG/Rij rats after chronic administration of antidepressants and saline and in non-epileptic Wistar rats. Administration of imipramine led to a significant decrease in the duration of REM sleep. The administration of imipramine, compared with fluoxetine, also increased the latency of the transition to sleep and the transition to REM sleep. Sleep spindle amplitude was significantly increased by both antidepressants. However, the spectral power density of “slow” and “medium” spindles, which predominate in WAG/Rij rats compared to Wistar rats, was significantly higher after administration of imipramine than fluoxetine. The results suggest that imipramine causes greater negative changes in the sleep-wake cycle and sleep spindles than fluoxetine. Studies in the WAG/Rij rat model indicate that fluoxetine is more preferable antidepressant for the treatment of depressive disorders comorbid with absence epilepsy, since it does not cause a significant deterioration in sleep quality. These results are consistent with clinical data.