Abstract

Stressors acting upon an individual cause stress reactions, aimed at mobilizing the organism, either to fight or to escape. They disturb, however, the functions of many systems and organs, including the alimentary tract. The most dangerous lesions of the alimentary tract caused by stress reactions are acute ulcerations of the gastric mucosa, the so-called stress ulcerations. One of the social characteristics of vertebrates is the hierarchy of domination and subordination. Differences in activation of particular components (axes) of the stress reaction have been noted between dominant and subordinate animals; the hypothalamic-adreno-medullary axis prevails in the case of dominant animals and the hypothalamic-adrenocortical one in the case of subordinates. The objective of the present study was to verify whether the position of an animal in the domination hierarchy affects the process of creating stress ulcerations of gastric mucosa, their size and histopathological features. Tests were performed on rats. Domination hierarchy was created for pairs of rats employing the model of competitive access to water. In order to create ulcerations of the gastric mucosa, animals were subjected to a water-immobilization stressor. Ulceration surface was measured employing a planimetric method. Stomach specimens were taken for histopathological analysis. Tissue specimens were stained with hematoxylin and eosin, following the PAS method and three color Masson's method and analyzed with the use of a light microscope. The data obtained indicates that dominant rats are much more resistant (by nearly 50%) to the effect of a water-immobilization stressor than subordinate rats and those which created no domination hierarchy. On the other hand, domination hierarchy does not influence the histopathological picture of the stress ulcerations produced. These results, along with a review of the literature suggests that the lower sensitivity of dominant rats to stress ulcerations of the gastric mucosa is associated with the prevailing hypothalamic-adrenomedullary axis and sympathetic activation in the stress reaction and with changes in the activity of the neurone systems. A final conclusion drawn on the basis of these results demonstrates that reaching a dominant position in domination hierarchy reduces the negative consequences of stress reactions, such as ulcerations of gastric mucosa.

Keywords: mucosa ulcerations