Basic Study
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World J Diabetes. Mar 15, 2020; 11(3): 52-65
Published online Mar 15, 2020. doi: 10.4239/wjd.v11.i3.52
Vitamin C ameliorated cardiac autonomic neuropathy in type 2 diabetic rats
Temitope Deborah Fabiyi-Edebor
Temitope Deborah Fabiyi-Edebor, Department of Physiology, Afe Babalola University Ado Ekiti, Ado 5454, Ekiti, Nigeria
Author contributions: Fabiyi-Edebor TD designed and performed the research, analysed the data and wrote the paper.
Institutional review board statement: The study was reviewed and approved by Afe Babalola University Institutional Review board.
Institutional animal care and use committee statement: All procedures involving animals were reviewed and approved by the Institutional Animal Care and Use Committee of Afe Babalola University with protocol number: [ABUAD-IRB/IACAU/2018/131].
Conflict-of-interest statement: There is no conflict of interest regarding this manuscript.
ARRIVE guidelines statement: The authors have read the ARRIVE guidelines, and the manuscript was prepared and revised according to the ARRIVE guidelines.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Temitope Deborah Fabiyi-Edebor, PhD, Senior Lecturer, Department of Physiology, Afe Babalola University Ado Ekiti, Kilometres 8.5 Afe Babalola Way, Ado 5454, Ekiti, Nigeria. fabiyitd@abuad.edu.ng
Received: August 6, 2019
Peer-review started: September 8, 2019
First decision: September 21, 2019
Revised: December 7, 2019
Accepted: January 13, 2020
Article in press: January 13, 2020
Published online: March 15, 2020
Processing time: 205 Days and 13.4 Hours
Abstract
BACKGROUND

Vitamin C (VC) is a common antioxidant with cell protection potentials. However, its possible protective effect on cardiac autonomic nerves from diabetic induced insults is yet to be explored.

AIM

To investigate the effects of VC on diabetic cardiac autonomic neuropathy.

METHODS

Thirty male Wistar rats were equally grouped into control, diabetic and diabetic + VC. Type 2 diabetes was induced with fructose diet and alloxan. VC (1 g/kg) was administered for 4 wk via oral canula. Blood pressure and heart rate were measured non-invasively using tail flick blood pressure monitor. Spectral analysis of heart rate variability (HRV) was used to assess cardiac autonomic neuropathy. Blood was collected from the ocular sinus for biochemical analysis. Urethane (1 g/kg-ip) was used for anaesthesia prior to HRV and cervical dislocation to harvest hearts. Intracardiac autonomic nerve was assessed using tyrosine hydroxylase immunohistochemistry on fixed heart sections.

RESULTS

Results were analysed using ANOVA at α0.05. Unlike VC and control groups, diabetic rats showed significantly (P < 0.0001) reduced HRV, increased heart-rate and blood pressure, initial increase in cardiac tyrosine hydroxylase activities at week-2 and sparse activity at week-4 of diabetes. Furthermore, apolipoprotein B, Oxidative stress and inflammatory markers were significantly (P < 0.01) reduced in VC treated rats.

CONCLUSION

VC possesses cardio-autonomic nerve protective potential and ameliorates the symptoms of cardiac autonomic neuropathy in type 2 diabetes. The possible mechanisms via which VC exert these effects may be via downregulation of oxidative stress, inflammation and apolipoprotein B.

Keywords: Vitamin C; Oxidative stress; Heart rate variability; Tyrosine hydroxylase; Autonomic nerve; Neuropathy; Type 2 diabetes

Core tip: This study reveals that vitamin C maintained normal heart rate variability, blood pressure and sympathetic tone in type 2 diabetic rats. Thus, preventing the symptoms of cardiac autonomic neuropathy. This is done via mechanisms related to downregulation of oxidative stress, inflammation and dyslipidaemia. Vitamin C may therefore possess cardio-autonomic nerve protection potential and may be used to prevent the development of cardiac autonomic neuropathy in type 2 diabetic subjects.