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©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
Minocycline fails to improve neurologic and histologic outcome after ventricular fibrillation cardiac arrest in rats
Andreas Janata, Ingrid AM Magnet, Kristin L Schreiber, Caleb D Wilson, Jason P Stezoski, Keri Janesko-Feldman, Patrick M Kochanek, Tomas Drabek
Andreas Janata, Ingrid AM Magnet, Kristin L Schreiber, Caleb D Wilson, Jason P Stezoski, Keri Janesko-Feldman, Patrick M Kochanek, Tomas Drabek, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, United States
Andreas Janata, Jason P Stezoski, Keri Janesko-Feldman, Patrick M Kochanek, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, United States
Andreas Janata, Emergency Department, KA Rudolfstiftung, Vienna 1030, Austria
Ingrid AM Magnet, Department of Emergency Medicine, Vienna General Hospital, Medical University of Vienna, Vienna 1090, Austria
Kristin L Schreiber, Jason P Stezoski, Tomas Drabek, Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, United States
Kristin L Schreiber, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, United States
Caleb D Wilson, Wyoming Otolaryngology, Wyoming Medical Center, Casper, WY 82604, United States
Author contributions: Janata A, Magnet IAM, Drabek T, and Kochanek PM designed the study; Janata A, Magnet IAM, and Drabek T conducted the study and collected the data; Janata A, Magnet IAM, Drabek T, Schreiber KL, Wilson CD, and Janesko-Feldman K analyzed the data; Janata A, Magnet IAM, Drabek T, Schreiber KL, Wilson CD, Stezoski JP, and Janesko-Feldman K prepared the manuscript; Stezoski JP performed the experiments and collected the biochemical and neurobehavioral data; Janesko-Feldman K prepared the histological slides; Kochanek PM coordinated the research.
Supported by the Laerdal Foundation for Acute Medicine to Janata A; the Erwin Schroedinger Stipend by the Austrian Science Fund (#J 2931-818) to Janata A; Medical Student Anesthesia Research Foundation Award from the International Anesthesia Research Society to Wilson CD; Seed Grant from The Department of Anesthesiology, University of Pittsburgh to Drabek T; Starter Grant from the Society of Cardiovascular Anesthesiologists to Drabek T; the Laerdal Foundation for Acute Medicine to Drabek T.
Institutional review board statement: The study protocol was approved by the Institutional Animal Care and Use Committee of the University of Pittsburgh on February 12, 2013 (Protocol #13021161).
Institutional animal care and use committee statement: The study protocol was approved by the Institutional Animal Care and Use Committee of the University of Pittsburgh on February 12, 2013 (Protocol #13021161). Principal Investigator: Tomas Drabek. Protocol Title: Neuroinflammation after prolonged cardiac arrest.
Conflict-of-interest statement: Dr Drabek reports grants from Society of Cardiovascular Anesthesiolgists, grants from The Laerdal Foundation for Acute Medicine, grants from Department of Anesthesiology, University of Pittsburgh, during the conduct of the study.
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 which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (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: Tomas Drabek, MD, PhD, Associate Professor, Research Scientist, FASA, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, 4401 Penn Avenue, Pittsburgh, PA 15224, United States. drabekt@anes.upmc.edu
Telephone: +1-412-6471687 Fax: +1-412-6240943
Received: June 21, 2019
Peer-review started: June 26, 2019
First decision: August 2, 2019
Revised: September 17, 2019
Accepted: October 27, 2019
Article in press: October 27, 2019
Published online: November 19, 2019
BACKGROUND
Prolonged cardiac arrest (CA) produces extensive neuronal death and microglial proliferation and activation resulting in neuro-cognitive disabilities. Among other potential mechanisms, microglia have been implicated as triggers of neuronal death after hypoxic-ischemic insults. Minocycline is neuroprotective in some brain ischemia models, either by blunting the microglial response or by a direct effect on neurons.
AIM
To improve survival, attenuate neurologic deficits, neuroinflammation, and histological damage after ventricular fibrillation (VF) CA in rats.
METHODS
Adult male isoflurane-anesthetized rats were subjected to 6 min VF CA followed by 2 min resuscitation including chest compression, epinephrine, bicarbonate, and defibrillation. After return of spontaneous circulation (ROSC), rats were randomized to two groups: (1) Minocycline 90 mg/kg intraperitoneally (i.p.) at 15 min ROSC, followed by 22.5 mg/kg i.p. every 12 h for 72 h; and (2) Controls, receiving the same volume of vehicle (phosphate-buffered saline). The rats were kept normothermic during the postoperative course. Neurologic injury was assessed daily using Overall Performance Category (OPC; 1 = normal, 5 = dead) and Neurologic Deficit Score (NDS; 0% = normal, 100% = dead). Rats were sacrificed at 72 h. Neuronal degeneration (Fluoro-Jade C staining) and microglia proliferation (anti-Iba-1 staining) were quantified in four selectively vulnerable brain regions (hippocampus, striatum, cerebellum, cortex) by three independent reviewers masked to the group assignment.
RESULTS
In the minocycline group, 8 out of 14 rats survived to 72 h compared to 8 out of 19 rats in the control group (P = 0.46). The degree of neurologic deficit at 72 h [median, (interquartile range)] was not different between survivors in minocycline vs controls: OPC 1.5 (1-2.75) vs 2 (1.25-3), P = 0.442; NDS 12 (2-20) vs 17 (7-51), P = 0.328) or between all studied rats. The number of degenerating neurons (minocycline vs controls, mean ± SEM: Hippocampus 58 ± 8 vs 76 ± 8; striatum 121 ± 43 vs 153 ± 32; cerebellum 20 ± 7 vs 22 ± 8; cortex 0 ± 0 vs 0 ± 0) or proliferating microglia (hippocampus 157 ± 15 vs 193 cortex 0 ± 0 vs 0 ± 0; 16; striatum 150 ± 22 vs 161 ± 23; cerebellum 20 ± 7 vs 22 ± 8; cortex 26 ± 6 vs 31 ± 7) was not different between groups in any region (all P > 0.05). Numerically, there were approximately 20% less degenerating neurons and proliferating microglia in the hippocampus and striatum in the minocycline group, with a consistent pattern of histological damage across the individual regions of interest.
CONCLUSION
Minocycline did not improve survival and failed to confer substantial benefits on neurologic function, neuronal loss or microglial proliferation across multiple brain regions in our model of rat VF CA.
Core tip: Prolonged cardiac arrest (CA) produces extensive neuronal death and neuroinflammation resulting in neuro-cognitive disabilities via ischemia-reperfusion injury. Minocycline was shown neuroprotective in some brain ischemia models, in part by blunting the microglial response or by a direct effect on neurons. In our established experimental CA model in adult rats, minocycline did not improve survival and failed to confer substantial benefits on survival, neurobehavioral outcome, neuronal loss or microglial proliferation across multiple brain regions.
