Relationships between neuro-endocrine, electrocardiogram, and gastric mucosal damage parameters in naїve and stressed rats
Authors: Fihura Oksana , Melnyk Oksana , Ruzhylo Sofiya , Zakalyak Nataliya , Kondratska Halyna , Zukow Walery , Popovych Igor 
Published: January 2024

Introduction
The first scientific publication on general adaption syndrome, or as we know today biologic stress has been published in Nature in 1936 by the 29-year old Hans Selye.1 Szabo et al2 in the anniversary review "Stress" is 80 Years Old” conclude that despite the extensive and multidisciplinary research on stress during the last 80 years, a lot of basic and clinical research is needed to better understand the manifestations, central and peripheral molecular regulators of stress response, especially the modes of prevention/management of distress or its transformation into eustress and the treatment of stress-related diseases.
In the vast majority of publications on stress, the HPA-, HPG- and autonomous systems are the objects of research, while the place in the general adaptation syndrome of such important hormones as calcitonin and PTH has been studied only in a few publications. Another methodological shortcoming of most studies is that the subjects of analysis are limited to a single neuro-endocrine system.
Therefore, we set ourselves the goal: to analyze relationships between some adaptation hormones, HRV, calcitonin, and PTH as well as electrocardiogram and gastric mucosal damage in naїve and post stressed rats.

Material and methods
Ethics approval
All animals were kept in room having temperature 22±2ºC, and relative humidity of 44-55% under 12/12 hours light and dark cycle with standard laboratory diet and water given ad libitum. Studies have been conducted in accordance with the rules and requirements of the “General Principles for the Work on Animals” approved by the I National Congress on Bioethics (Kyїv, Ukraine, 2001) and agreed with the provisions of the “European Convention for the Protection of Vertebrate Animals used for Experimental and other Scientific Purposes” (Council of Europe No 123, Strasbourg 1985), and the Law of Ukraine “On the Protection of Animals from Cruelty” of 26.02.2006. The removal of animals from the experiment was carried out under light inhalation (ether) anesthesia by decapitation.
Participants
The experiment is at 38 rats Wistar line: 18 males (Weight Mean=227 g; SD=25 g) and 20 females (Mean=214 g; SD=27 g).
Study design and procedure
Due to the purposeful formation of groups, the potential predictors of post-stress reactions of the neuro-endocrine-immune complex and the metabolome3,4,5 were almost identical both in mean values and, to a lesser extent, in variance (SD). In particular, the hypoxic test (sec) was: 136±59 and 133±81; swimming test (min): 19±11 and 19±17; HRV Stress index4 (units) as (AMo/2*Mo*MxDMn)1/3: 0,14±0,08 and 0,14±0,05 in intact animals and those exposed to acute stress.
Results and discussion
Adhering to the algorithm of the Truskavetsian Scientific School of Balneology, we recalculated the current values of the parameters in Z-scores. This approach makes it possible to adequately compare deviations from the norm of parameters expressed in different units and with different variability.10,11,12 This is all the more important in view of sexual dimorphism in endocrine parameters. In addition to drastically higher levels of testosterone (41.8±1.7 vs 3.53±0.24 nM/L), males have higher levels of calcitonin (36±6 vs 21±4 ng/L), but lower levels of parathyroid hormone (154±12 vs 185±3 ng/L), adrenals mass (44±5 vs 65±5 mg), corticosterone (340±45 vs 466±57 nM/L), and aldosterone (587±8 vs 639±24 pM/L).
Conclusion
The condition of the gastric mucosa and myocardium as essential targets of stressors is determined by the damaging and protective effects of adaptive hormones and the autonomic nervous system.