Sex features of the development of oxidative stress in high and low hypoxic resistancy rats, which experienced repeated stressful episodes of immobilization
Authors: Denefil Olha V. , Miroshnyk Viktoria A. , Venher Olena P. , Usynskyi Ruslan S. , Liuta Olha O. , Fedoniuk Larysa Ya. 
Published: December 2024

Aim: of the study was to find out the sexual characteristics of the development of oxidative stress in rats with high and low resistance to hypoxic hypoxia (HRH, LRH) during repeated stressful episodes of immobilization.
Materials and Methods: The study was performed on 96 white HRH, LRH male and female Wistar rats. The animals were divided into eight groups: 1 – control (HRH, LRH) males and females, 2 – immobilization (HRH, LRH) males and females. Immobilization stress was induced by gently restraining the animals four Times by all paws and maxillary central incisors dorsally for 1 hour at an interval of 72 hours. The concentration of diene and triene conjugates (DC, TC), Schiff’s bases (SB), TBA-active products (TBA-ap), activity of superoxide dismutase (SOD) and catalase (CAT), reduced glutathione (GSH), activity of glutathione peroxidase (GP) and glutathione reductase (GR) were determined in the homogenate of heart. A morphological study of heart preparations stained with hematoxilin and eosin was carried out. All studies were performed in control, after 24 hours after last immobilization.
Results: In control HRH, compared to LRH males, the values of TBA-ap were found to be lower. Under stress, an increase of LPO was noted in HRH and LRH males, only SB decreased. Higher level of LPO products noted in LRH rats compared to HRH. In control HRH females, compared to LRH, the content of DC, SB were higher and TBA-ap – lower. In HRH females, compared to HRH males, TC was higher and SB – lower. Under stress, in HRH females DC and TBA-ap were increased, TC and Sb – decreased. In LRH females all indicators increased. Lower TC and TBA-ap values were noted in HRH compared to LRH females rats. In control HRH males, compared to females, lower TC and higher values of SB were found. In LRH males, compared to females, the values of DC, TC, SB were higher. During stress, a more intensive course of LPO was noted in males. SOD in control HRH males, compared to LRH, was higher; CAT was not statistically different. Under stress, SOD decreased, CAT – increased. In HRH males, compared to LRH, in this group SOD was higher CAT – lower. In the control, HRH females, compared to LRH, had higher SOD, lower – CAT. Under stress, CAT increased in HRH females; in LRH females CAT decreased and SOD – increased. In HRH females, compared to LRH, CAT was higher. In control males, compared to females, SOD and CAT was higher. Under stress higher SOD was in females, and CAT – in males. GSH and GP were higher in control HRH compared to LRH males and females. Under stress, in males the GSH increased, GR decreased; GP in HRH decreased, in LRH it increased. HRH males, compared to LRH, GSH and GR were higher, GP – lower. Under stress, in females GSH, GP, GR in females decreased; HRH, compared to LRH, had higher GP and GH. In intact HRH males, compared to females, was higher GR and less GP; in LRH males, compared to females, GR was higher. Under stress, males had higher GSH, GP and GR values compared to females. The studied biochemical changes in the heart are accompanied by alterative changes in the structural components of the myocardium in the experimental groups.
Conclusions: Congenital resistance to hypoxia is associated with a greater power of the enzymatic and non-enzymatic links of the antioxidant system. Immobilization stress repeated four times with an interval of 72 hours is accompanied by the most significant increase in the content of lipid peroxidation products in the heart homogenate of lower resistant to hypoxia rats, especially males. A decrease in Schiff bases is observed in all males and highly hypoxia-resistant females. In males, a more intense accumulation of lipid peroxide oxidation products, higher catalase activity and a more active glutathione system were noted. Females have significantly higher superoxide dismutase activity. Morphological changes confirm more damage to the heart of low hypoxia-resistant rats, more males.
KEY WORDS : heart, sex, rats, resistancy to hypoxia, biochemical changes, morphological changes, oxidative stress, lipid peroxidation, antioxydants