No abstract

The thromboembolic ischemia model is one of the most applicable for studying ischemic stroke in humans. The aim of this study was to develop a novel thromboembolic stroke model, allowing, by affordable tools, to reproduce cerebral infarction in rats. In the experimental group, the left common carotid artery, external carotid artery, and pterygopalatine branch of maxillary artery were ligated. A blood clot that was previously formed (during a 20 min period, in a catheter and syringe, by mixing with a thromboplastin solution and CaCl2) was injected into the left internal carotid artery. After 10 min, the catheter was removed, and the incision was sutured. The neurological status of the animals was evaluated using a 20-point scale. Histological examination of brain tissue was performed 6, 24, 72 h, and 6 days post-stroke. All groups showed motor and behavioral disturbances 24 h after surgery, which persisted throughout the study period. A histological examination revealed necrotic foci of varying severity in the cortex and subcortical regions of the ipsilateral hemisphere, for all experimental groups. A decrease in the density of hippocampal pyramidal neurons was revealed. Compared with existing models, the proposed ischemic stroke model significantly reduces surgical time, does not require an expensive operating microscope, and consistently reproduces brain infarction in the area of the middle cerebral artery supply.

Background: The temperature preferences of cold-blooded animals are different for different groups of animals and are closely related to their evolutionary status and level of adaptive capabilities. The range of preferred temperatures for reptiles (28˚C -32˚C) coincides with the zone of temperature-dependent increase in the rate of the M-cholinergic reaction in the brain, which was previously found in warm-blooded neurons. The growth of the M-cholinergic process contributes to the transition of adaptive behavior to a higher level. Of the cold-blooded, only reptiles actively use thermoregulatory behavior as a tool to achieve a temperature optimum. This paper is devoted to the study of the behavior of red-eared turtles aimed at reaching the range of preferred temperatures. Temperature conditions necessary for the survival of different groups of cold-blooded animals are compared and the reason for temperature preferences is discussed. Methods: The behavior of turtles was studied under conditions of variable solar radiation and in a 3-section terrarium with gradual temperature ranges: 23˚C -24˚C; 28˚C -31˚C and 45˚C -50˚C. Results: It was found that prolonged (up to 1.5 hours) heating at a temperature of 45˚C -50˚C was the best way to achieve the preferred temperatures. This method of heating results in increasing the temperature of the shell to an average of 37˚C, followed by a very slow decrease during 4 -6 hours within the limits that closely coincided with the preferred level. Conclusion: The results obtained demonstrate that the main function of the turtle shell is to accumulate heat and keep it for a long time in a variable climate. The preferred temperature achieved in this case is necessary for the temperature-dependent transition of the rate of the M-cholinergic reaction in the How to cite this paper: Mednikova, Yu.S. and Kalabushev, S.N. (2023) Thermally Dependent Behaviour of Cold-Blooded Animals: Overcoming Two Temperature Barriers on the Way to Warm-Blooded. Journal of Behavioral and Brain Science, 13, 95-112.

Purpose of the study. To evaluate the influence of sublethal dose of Clozapine on the functional and morphological parameters of the cardiovascular system in rats 4 hrs. after the drug administration.Materials and methods. The experiments were carried out on male Wistar rats weighing 200–250g (n=14). Group I received 0.9% NaCl solution administered via enteral feeding tubing under general anesthesia using Sevoflurane; group II — Clozapine dosed at 150 mg/kg in 0.9% NaCl solution; group III — Clozapine dosed at 150 mg/kg in 40% ethyl alcohol solution. 4 hrs. after drug administration, arterial blood pressure (ABP), heart rate (HR), microcirculation in the skin using laser Doppler flowmetry (LSF), fluorescence intensity of coenzymes NADH and FAD were evaluated. After euthanasia, autopsy including withdrawal of the internal organs of rats for morphological analysis was performed. Thereafter, paraffin sections of hearts were made and subsequently stained with hematoxylin and eosin, which were later examined with the help of light microscope Nikon Eclipse Ni-U.Results. In both Clozapine groups, ABP and blood flow in the skin were lower than in the control group: ABP — by 12% in group I and by 15% in group II; blood flow — by 48% and 37%, respectively. No significant difference between the groups was observed in respect of the microcirculation indices studied. Increased fluorescence intensity of coenzyme NADH in the skin was found in the Clozapine groups compared to the control group (2.3-fold in group I and 1.9-fold in group II). Histological analysis of the hearts of animals that received Clozapine established uneven blood filling, erythrocyte sludges, fine-focal hemorrhaging, endotheliocyte nuclei oriented perpendicular to the basal membrane, uneven staining of myocardium with hypereosinophilic segments, fragmentation and undulating deformity of muscle fibers.Conclusion. During acute Clozapine poisoning, morphological signs of disturbed circulation and myocardium damage are found in the heart, which are accompanied with development of myocardium dysfunction with arterial hypotension and decreased peripheral blood flow, also disturbed oxidative metabolism in peripheral tissues.