Slobodianyk N. Pathogenetic substantiation of correction of pathological changes in pancreas depending on stress resistance of animals

This dissertation is aimed at investigating individual typological characteristics arising during the development of stress-induced damages to pancreas in rats and the possibility to correct these pathological changes by melanin. It has been proven that under the acute stress model, the development of the stress syndrome in the pancreas depends on the individual typological characteristics of the body. The maximum expressed changes in the development of pathological processes in the pancreas of the rats exposed to acute stress are observed in the stress-susceptible animals compared with the stress-resistant rats, as evidenced by the development of proteinase-inhibitory imbalance of decompensation type, by activation of free radical oxidation against the suppressed antioxidant defence, increased endogenous toxicosis, and cytolytic syndrome, as well as by the development of the NO-ergic system imbalance. It has been found out that melanin administration 30 minutes before the onset of acute stress modelling leads to the prevention of the thymus involution that is demonstrated by a significant increase in thymus weight, in 1.37 times higher in the stress-resistant animals, and in 1.37 times higher in the stress-susceptible animals compared with the stressed rats of the same stress response types. The melanin administration 30 minutes before the onset of acute stress modelling resulted in decreased adrenal hypertrophy as evidenced by a significant double decrease in adrenal mass, exactly in 1.18 times in the stress-resistant animals and in 1.34 times in the stress-susceptible animals compared with the stressed rats of the same stress response types without correction. Melanin eliminated ulcerogenic effect of stress syndrome in all groups of the animals studied that ranged from the total absence of the gastric mucosa ulceration in stress-resistant animals to a decrease in incidence rate and multiplicity of ulcers in the stress-susceptible animals compared with the corresponding control. The research has shown that under the prior melanin administration, the stress-resistant animals demonstrate the normalization of the proteinase-inhibitory potential in the pancreas: the probable inhibition of the total proteolytic activity against the increasing activity of proteinase inhibitors compared with the corresponding types of rats exposed to acute stress without correction. The preventive introduction of melanin before the onset of acute stress modelling prevents the development of the cytolytic pancreas syndrome in the stress-susceptible animals, as evidenced by a significant decrease in the activity of amylase and lipase compared to the corresponding types of the rats in acute stress without correction. We have proven the suppression of oxidative stress in the pancreas of the stress-susceptible animals under the conditions of melanin administration by a probable decrease in the content of TBC-reactants, medium-weight molecules against the probable increase in the activity of catalase and superoxide dismutase compared to the corresponding types of rats under conditions of acute stress without correction. Biochemical investigations of the peculiarities related to the development of stress-induced damage to the pancreas in the animals depending on the stress resistance of their body are confirmed pathomorphologically.