Study of the Effect of Preconditioning with Succinic Acid Salt of Choline (1:2) on the Disturbances of Energy Metabolism in the Brain during Ischemia by 31P NMR In vivo

Abstract

It is known that short-term hypoxia or ischemia may temporarily increase brain resistance to subsequent ischemic insult [1,2]. The mechanisms of this phenomenon, which was termed preconditioning, are not studied well.One of the consequences of ischemia is a rapid simultaneous increase in the concentrations of several metabolites, including succinic acid (SA) and choline [3]. A role of these metabolites as potential mediators of preconditioning is not studied.The purpose of this work was to study the role of metabolites, which concentration is increased during ischemia, in the protective effect of preconditioning. The levels of phosphates, which are the main players in the energy metabolism of brain, were studied by NMR spectroscopy in vivo in rats preconditioned with the model drug succinic acid salt of choline (1:2) (SSC) using the model of total ischemia.The dynamics of phosphates involved in energy metabolism during total brain ischemia was used as an assessment criterion of the preconditioning effect. This selection was based on the fact that a decrease in the brain energy status due to deficiency in the blood-transported energy substrates and oxygen, required for ATP synthesis, is the triggering mechanism in the development of injuries induced by the brain ischemia [4].Because NMR spectroscopy in vivo , is a noninvasive method, it excludes experimental artifacts associated with the extraction of brain tissues and provides continuous monitoring of parameters detected, such as phosphates [5].In this study we demonstrated that SSC, administered into animals as a preconditioning agent, decelerates a decrease in the concentration of energy-rich phosphates (ATP and creatine phosphate (CP)) and a decrease in energy status of rat brain during total ischemia. Therefore, SSC may be regarded a mediator of ischemic preconditioning.SSC (10% solution in saline; dose, 10 mg/kg body weight) was injected into male Wistar rats (the experimental group) daily for seven days. The control animals were injected with saline.The levels of phosphate metabolites (such as ATP, CP, inorganic phosphate (P i ), and phosphate monoesters (PME)) and intracellular pH were measured in animals narcotized with Nembutal on day 8 after the beginning of the experiment using in vivo 31 P NMR.Brain spectra were recorded in an NMR-spectrometer AM-400WB (Bruker) at a frequency of 161.98 MHz for 31 P nuclei using a sensor with a surface coil, which was constructed for NMR studies of rat brain in vivo [6]. The conditions of spectrum recording were described in [7].Total ischemia in rats was modeled immediately after measurement in the sensor of the NMR spectrometer by arresting the heart with the use of alternating current at 27 V. The current was applied for 4 min on a pair of needle electrodes fixed under the skin of the chest. The 31 P brain spectra were recorded in vivo at 1-min intervals starting from the first minute. Each spectrum was recorded for 1 min. Measurements were performed for 15 min.The spectrum processing is described in [7]. The levels...

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“…Of the 466 articles related to energy metabolism, 51 include focal ischemia, 125 include fore-brain ischemia, and 53 include global ischemia, but only 12 mention the word "penumbra," and only 2 or 3 use the terms "peri-infarct" or "boundary zone." Due to technical limitations, previous research on energy metabolism of ischemic stroke has been struggling at the level of the substrate, such as glucose (Chang et al, 1998;Katayama et al, 1998), fructose-1,6-bisphosphate (Kaakinen et al, 2006), pyruvate (Yi et al, 2007), succinate (Pomytkin and Semenova, 2005), citrate (Mack et al, 2006), nicotinamide (Yang et al, 2002), ubiquinone (Tsukahara et al, 1999), oxygen (Rogatsky et al, 2003;Singhal, 2007), and hydroxybutyrate (Ottani et al, 2003;Ottani et al, 2004;Vergoni et al, 2000). Perhaps it is complacency that has partially caused the reluctance of stroke researchers to address penumbral energetics, the fundamental issue in acute stroke.…”