ORIGINAL RESEARCH
Alleviation of neurological and cognitive impairments in rat model of ischemic stroke by 0.5 MAC xenon exposure
1 Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
2 Negovsky Research Institute of General Reanimatology, Federal Research and Clinical Center of Intensive Care Medicine and Rehabilitology, Moscow, Russia
3 Sechenov First Moscow State Medical University, Moscow, Russia
4 Sklifosovsky Institute for Emergency Medicine, Moscow, Russia
Correspondence should be addressed: Rostislav A. Cherpakov
B. Cherkizovskaya, 6, korp. 6, k. 36, Moscow, 107061, Russia
Funding: the study was funded by the Federal Research and Clinical Center of Intensive Care Medicine and Rehabilitology state budgetary institution of science as a part of research project "Anesthetic neuroprotection with xenon and sevoflurane in severe brain damage. Clinical and experimental study" (No. 0427-2019-0035).
Author contribution: Krukov IA — study design, concept development and research algorithm establishment; Ershov AV — experimental part, statistical analysis of the data; Cherpakov RA — manuscript writing and editing; Grebenchikov OA — scientific editing of the final version.
Compliance with ethical standards: the study was approved by Ethical Review Board at the Federal Research and Clinical Center of Intensive Care Medicine and Rehabilitology (Protocol № 4/21/2 of 29 September 2021) and conducted in compliance with the European Convention for the Protection of Vertebrate Animals used for Experimental and other Scientific Purposes (ETS № 123, Strasbourg 18/03/1986, with the Appendix of 2006), Guide for the Care and Use of Laboratory Animals, 8th ed. (2010), Directive 2010/63/EU of the European Parliament and the Council on the Protection of Animals Used for Scientific Purposes (2010) and the Good Laboratory Practice Guidelines (2016).
The majority of stroke patients have cognitive symptoms and about 50% of them live with neurological deficits that critically limit social adaptation capacities even in the absence of significant motor impairments. The aim of this study was to select the optimal length of 0.5 MAC xenon exposure in order to alleviate the neurological and cognitive impairments in experimental stroke. The focal ischemia-reperfusion injury was modeled in rats (n = 70) ising Longa method. The intervention was immediately followed by inhalation of 0.5 MAC xenon for 30, 60 or 120 min. The neurological deficit was assessed using a 'Limb placement' seven-test battery and the cognitive functionalities were assessed by the Morris water maze test. A 30 min 0.5 MAC xenon exposure provided a 40% increase in the limb placement scores and a 17.6% decrease in the Morris water maze test latency compared with the control group (р = 0.055 and р = 0.08, respectively). With a longer 60 min exposure, the trends became significant, the scores improving 2-fold and by 44.4% compared with the control group (р = 0.01 and р = 0.04, respectively), whereas 120 min exposures afforded 2-fold improvements in both tests (р = 0.01). We conclude that, although 30 min post-stroke inhalations provide negligible benefits in terms of neurological status and learning capacity, prolonged exposure times of 60–120 min afford significant improvement in neurological and cognitive indicators and largely alleviate the deteriorating ischemic damage.
Keywords: cognitive impairment, stroke, xenon, neurological deficiency