The initial level of heart rate variability determines the dynamics of the neuropathy of the autonomic nervous system and temperature sensitivity in rats with streptozotocin diabetes

Abstract

BACKGROUND: The development of diabetes mellitus (DM) is accompanied by hyperglycemia, which leads to the development of neuropathy. We assume that the individual characteristics of the organization of the autonomic nervous system (ANS) in humans affect not only the ability to withstand stress, but can determine the course of diseases, including diabetes.
 AIMS: The study of the dynamics of heart rate variability and temperature sensitivity in rats against the background of hyperglycemia depending on the organization of the initial regulation of the heart under ANS.
 MATERIALS AND METHODS: 70 male rats were randomized by weight and level of total heart rate variability (HRV) on animals with initially low and high levels of total HRV. Diabetes was modeled by a single i.p. injection of streptozotocin (STZ). The control group received a single i.p. injection of citrate buffer (CB). Before the induction of diabetes, as well as on 21, 42 and 70 days after the injection of STZ, a comprehensive examination of rats condition was carried out: 1) assessment of HRV; 2) analysis of temperature-pain sensitivity; 3) assessment of glucose and ketone bodies in the blood. Similarly, animals in the CB group were examined.
 RESULTS: The change in HRV and temperature-pain sensitivity in rats depends on the initial level of HRV. In rats with low variability, the reaction time in the pain test increased by 832% from the 28th day of the experiment, from 21 days the bradycardia increased and the decrease in individual HRV indices at rest, but not the response of these parameters to cold stress.
 CONCLUSION: The development of ANSs lesion depends on the initial level of HRV. Low variability animals are more resistant to hyperglycemia: the normal ranges of CP reactions from the side of HR, the parameters of total HRV and the CVHS contribution to it are longer, but there is a loss of temperature sensitivity. Initially, highly variable rats with the development of diabetes do not lose temperature sensitivity, but demonstrate an imbalance in the regulatory circuits of heart rate and HRV.