Reactive Oxidant Species in Rat Brain Extracellular Fluid

Abstract

Reactive oxidant species (ROS) include oxygen free radicals, hydrogen peroxide, lipid peroxides and hydroperoxides, singlet oxygen, oxygen redox-cycling molecules such as quinones and hydroquinones, hypochlorite, and peroxynitrite (Ames et al., 1989; Ames et al., 1981; Aruoma et al, 1989; Beckman et al., 1990; McCord, 1968; Pryor, 1986; Puppo et al., 1990). ROS contribute to damage in a variety of tissues during pathophysiological states, including insults to the central nervous system that result in neuropathology (Kontos, 1989; Siesjo et al., 1989a). Proving ROS participation in tissue damage and occurrence in vivo is difficult due to the characteristic short half-lives of these reactive molecules. Methods for ROS detection in vivo include: (a) administering free radical spin trapping agents to animals followed by electron spin resonance spectroscopy of tissue homogenates (Carney and Floyd, 1991; Imaizumi et al., 1986; Lai et al., 1986; Oliver et al., 1990), ( b) salicylate administration to animals, which can form adducts with ROS, followed by high performance liquid chromatography with electrochemical detection (Cao et al., 1988; Floyd et al., 1984), (c) nitroblue tetrazolium and cytochrome c reduction by electron transfer reactions with ROS in biological systems with subsequent spectrophotometric quantification (Armstead et al., 1989; Kennedy et al., 1989; Kontos et al., 1985; Kontos and Povlishock, 1986; McCord, 1968), and (d) ROS-initiated chemiluminescence, or light production by excited molecules, which can be assayed in various animal models (Boveris et al., 1980; Flecha et al., 1991).