Differences in behavioral patterns and resistance to stress-induced gastric ulceration between August and Wistar rats adapted and unadapted to hypoxia

Abstract

The incidence of gastric ulceration induced by acute emotional stress in Wistar rats is 3 times higher than in August rats, and the mean number of gastric ulcers in Wistar rats 6.3-fold surpassed that in August rats. Wistar rats predisposed to stress-induced ulceration displayed suppressed locomotor and exploratory activities in the open field test, while August rats had more stable behavioral patterns and enhanced exploratory activity after stress. Short-term preadaptation to hypobaric hypoxia for 6 days attenuated stress-induced gastric ulceration, whereas long-term adaptation (40 days) aggravated the severity of gastric ulcers in August and Wistar rats. The interstrain differences in stress-induced ulceration persisted after adaptation. The data suggest that these differences are related to genetically determined peculiarities of production and metabolism of NO and glucocorticoids in August and Wistar rats. Key Words: August and Wistar Rats; stress; ulcer formation; adaptation; behaviorAugust rats are less resistant to stress-induced damages to the cardiovascular system than Wistar rats, which are assumed to be more resistant to emotional stress [9,13]. However, in stressed August rats the rise in blood concentration of creatine phosphokinase (marker of injuries) is less pronounced [8], and the primary immune response to sheep erythrocytes was greater than in stressed Wistar rats [11]. Therefore, various systems of the body have different genetically determined resistances to stress-induced damages. Here we studied gastric ulceration and behavioral changes induced by emotional stress in August and Wistar rats. The effect of preadaptation to hypobaric hypoxia (AH) possessing protective properties in stress [7] on stressinduced gastric ulceration was assessed. MATERIALS AND METHODSExperiments were performed on 129 male August and Wistar rats weighing 250+30 and 300• g, respectively. In series I, stress-induced formation of gastric ulcers in intact rats and animals adapted to hypobaric hypoxia was studied, In series II, open field (OF) behavior of intact fasted or sated rats and stressed fasted rats was tested [14], The rats deprived of food for 24 h were placed for 30 min into a standard cage (50x30x20 cm) filled with water (22~ 15-cm layer) and covered with a grid (5 cm form water surface) [1]. The total length and area of gastric ulcers were assessed 1 h after stress. The OF behavior of each rat was tested for 4 rain, and the numbers of peripheral and central ambulations (horizontal activity) and peripheral and central rearings with and without support (vertical activity) were recorded. Long-term and shortterm AH were conducted in a hypobaric pressure chamber of the extract-and-influx type. Long-term AH was performed for 1, 2, 3, and 4 h at simulated alti-9

Resistance to Neurodegenerative Brain Damage in August and Wistar Rats

“…The index of vertical activity in August rats was higher than in Wistar rats (Table 1). These data indicate that August rats are characterized by a higher orientation and exploratory activity, which agrees with published data [5]. β-Amyloid treatment increased horizontal (locomotion) and vertical activity in August rats.…”

“…This conclusion was derived from studying of the number of "remembering" animals and retention score (∆LP). The study of indexes for memory impairment suggests that in August rats higher resistance to acute stress [4,5] is associated with higher resistance to neurodegenerative damage.…”

“…August rats are more resistant to emotional stress than Wistar rats [5]. Stress exposure induces a weaker stress response in August rats, which is accompanied by less severe damage (compared to Wistar rats) [6].…”

Specific Response of the Organism and Blood Leukocytes in Rats of Different Genetic Strains to Hypoxia

“…Moreover, Wistar rats exhibited a lower number of explored holes than August rats. These results are consistent with published data [7]. We conclude that August rats are characterized by lower emotional reactivity and greater resistance to novelty (OF exposure) than Wistar rats.…”

Synthesis of heat shock proteins (HSP70) in blood leukocytes as a criterion of the resistance to stress injury

“…The number of ulcers (per 1 stomach) in August rats was 2.3-fold lower than in Wistar rats. These data are consistent with the results of our previous studies that August rats are more resistant to acute stress than Wistar rats [10]. After acute stress, the relative weight of the thymus decreased in August rats (by 16%), but remained unchanged in Wistar rats.…”