STRESS EFFECT ON MALE AND FEMALE RATS’ ORGANISMS WITH VARIOUS HYPOXIA RESISTANCE

Abstract

Objective is to study correlation between the level of stomach lesion, the system of antioxidant protection and regulation mechanisms of autonomous nervous system (ANS) in high-resistant and low- resistant to hypoxic hypoxia (HRH, LRH) rats of both sexes in response to chronic stress. Materials and methods. The experiments were carried out on 96 highresistant and low- resistant (HRH, LRH) female and male rats of Wistar line. The first group is control set, in the second group chronic stress was imitated (an hour-long immobilization of animals down of their back in 72 hours interval, four times). Euthanasia of rats was performed under sodium thiopental anesthetic, blood was taken for the determination of ceruloplasmin (CP) content, peroxidase blood activity (PBA) and stomach (macroscopic changes, the amount of hemorrhages, erosions and ulcers were determined in mucous membrane of the stomach (MMS), estimating their rate and multiplicity). Variation cardio intervalometry (“Cardiolab”, Ukraine) was carried out, estimating variation range (VR, c); modes (Mo, c); amplitude modes (AMo, %); stress index (SI ). Statistical analysis of figures was done with the help of «Excel» and «STATISTICA» 6.0. Reliability of differential values was determined according to Student criterion and distribution-free (nonparametric) methods. Results. CP and PBA were higher in the control group of HRH animals than in LRH. CP and PBA were increased under the stress, but in HRH males they remained larger than in LRH; CP increased in females, PBA decreased (CP was larger in HRH than in LRH, PBA was less). In the control group of males PBA was higher, but in females CP was higher. CP and PBA proved to be larger in females under the stress. Cardio intervalography revealed larger AMo and SI in the control group of LRH animals than in HRH. Mo increased in males under the stress; AMo and SI were higher in LRH animals but VR was higher in HRH ones. Variations of indices were noted in LRH only: Mo and VR were decreased but SI was increased. Mo and VR were less in LRH but AMo and SI were larger than in HRH. The control group of HRH males had less Mo than females, but they had larger AMo and SI, VR was less. The control group of LRH males had lower Mo, but higher AMo and less SI under the stress. Chronic stress caused the lesion of mucous membrane of the stomach. This was more noted in LRH females: thinning and folding of mucous membrane, hemorrhage comprised 75 %, ulcers – 25 % of animals. Conclusions. HRH animals of both sex groups have more powerful antioxidant protection than LRH animals: the content of CP is higher in females, PBA is higher in males. CP of all rats increases under the stress, but PBA changes depend on sex group (in males they increase, in females- decrease). The activity of sympathetic part of ANS and tension of regulatory mechanisms predominate in the control group of LRH males and females rats over HRH animals. The activity of sympathetic part of ANS by humoral canals decreases in males under the stress, but sympathetic regulation by nervous canals and the tension of regulatory mechanisms remain higher in LRH, parasympathetic is higher in HRH. The increase of sympathetic activity by humoral canals, the decrease of parasympathetic activity, longer tension of regulatory mechanisms are observed in LRH females under the stress. All groups of animals under chronic stress were noted to have macroscopic lesions of mucous membrane of the stomach, but LRH females were the most vulnerable. Original