Influence of behavioral phenotype on the response of the rat body to cold stress in control and after hypoxic preconditioning

Abstract

Studying the cold resistance of homoiothermic organisms is important for identifying general physiological mechanisms, as well as for assessing individual phenotypic variations. The aim of the work was to study the effect of the behavioral traits of Wistar rats, pre-evaluated in Barnes maze task, on cardiorespiratory functions disorder during cooling. Тhe behavioral testing reveals exploratory activity and working memory. Two different psychotypes have been identified, one with increased impulsivity during learning (No.1 – “proactive”) and the other with poor exploratory activity and reduced cognitive flexibility during retraining (No.2 – “reactive”). Some rats of both psychotypes were subjected to a moderate hypobaric hypoxia (three daily exposures at 360 mmHg, each lasting 2 hours), the others served as a control. On the fourth day after last behavioral trial, all rats were urethane anesthetized and cooled in water bath (9-10 °C) until respiration stopped. Frequency of breathing, heart rate and body temperature were recorded. It was revealed that rats of psychotype No.2 showed greater cold resistance and greater sensitivity to neuroprotective hypoxic preconditioning than psychotype No.1. Our results could be valuable not only for fundamental psychophysiology, but also for medicine dealing with dip cooling situations.