EXPERIMENTAL INFECTION OF LABORATORY RATS OF NEMATODE LARVAE EUSTRONGYLIDES EXCISUS (NEMATODA: DIOCTOPHYMATIDAE)

Abstract

The article presents data on the results of research work on the installation of reference pH values of stomach acidand its volume selected in laboratory rats for the introduction of a different amount of 1 % hydrochloric acid solution and without it. As a result of the research, it was found that in the intact group of experimental animals the pH level of stomach acidwas 3.7 ± 0.67 (p ˃ 0.001), and the latter volume was 2.1 ± 0.07 ml (p ˂ 0, 01). With the introduction of 0.5 ml of 1 % solution of hydrochloric acid in the stomach of rats through a orogastric tube, a statistically significant decrease in the pH of the stomach acid, in this group of animals, was found to be 41.35 % compared to intact rats. The pH level in this group of animals was 2.17 ± 0.1 (p ˃ 0.01). The volume of stomach acidincreased compared with the control group of rats (2.1 ± 0.07 ml), by 14.98 % and was 2.47 ± 0.11 ml (p ˃ 0.01). A group of rats received a 1% solution of hydrochloric acid in a dose of 1 ml was also characterized by changes in the pH of the stomach acidand its volume. Thus, in this group of experimental rats, the pH level of stomach acidwas significantly reduced by 67.56 % compared with the control group of animals and was1.2 ± 0.13 (p ˃0.02). The level of secretion of stomach acidin this group of animals increased by 18.91 %, and was 2.59 ± 0.12 ml (p ˂ 0.01). The second stage of the research was carried out in order to establish the influence of pH and gastric secretion on the survival of the larvae of the nematode Eustrongylides excisus in the body of a mammal – a laboratory rat, as characteristic of this parasite, the host. So in the process of research it was found that with the introduction of 50 larvae of Eustrongylides excisus to the gastrointestinal tract of a group of intact rats, after the waiting time had passed, only 9 larvae were found. The survival rate of the parasite larvae in the body of experimental animals of this group was 18 %. It should be noted that in one animal of this research group, after opening, not a single larva was found. Obviously, the survival of parasites in the gastrointestinal canal of a laboratory rat did not occur, and the parasites died and were eliminated. Among the animals of the second experimental group, which were simultaneously injected with a orogastric tube 0.5 ml of 1 % hydrochloric acid solution and a certain number of nematode larvae, showed at the end of the experiment, a total of 19 live larvae out of 50 helminths invasive in laboratory rats at the beginning of the research. It is interesting to note that in one rat of the second experimental group 7 parasites were detected, showed all signs of vital activity. This number of detected larvae, according to the experimental group, was the highest, with an average number of parasites in this experiment – 3.8 copies. Therefore, the number of parasites that survived during the experiment in the body of infected animals was 38 %. As a result of the simultaneous introduction into the stomach of experimental rats of the third group, 1 ml of 1 % solution of hydrochloric acid and 50 larvae of the nematode under study was established after a waiting time of 26 larvae. The parasite larvae showed all signs of vitality: they reacted to mechanical stimuli and were mobile. Therefore, the percentage of parasite survival with which rats of the third group were infected was 52 %. The fourth group of animals was the control.

Keywords: experimental infection, gastric juice, pH, rats, Eustrongylides excisus, fish, survival, pathological and anatomical changes, Black Sea, Dnieper-Bug estuary, Nikolaev and Odessa regions