Cerebral Ischemia Enhances Polyamine Oxidation: Identification of Enzymatically Formed 3-Aminopropanal as an Endogenous Mediator of Neuronal and Glial Cell Death

Abstract

To elucidate endogenous mechanisms underlying cerebral damage during ischemia, brain polyamine oxidase activity was measured in rats subjected to permanent occlusion of the middle cerebral artery. Brain polyamine oxidase activity was increased significantly within 2 h after the onset of ischemia in brain homogenates (15.8 ± 0.9 nmol/h/mg protein) as compared with homogenates prepared from the normally perfused contralateral side (7.4 ± 0.5 nmol/h/mg protein) (P <0.05). The major catabolic products of polyamine oxidase are putrescine and 3-aminopropanal. Although 3-aminopropanal is a potent cytotoxin, essential information was previously lacking on whether 3-aminopropanal is produced during cerebral ischemia. We now report that 3-aminopropanal accumulates in the ischemic brain within 2 h after permanent forebrain ischemia in rats. Cytotoxic levels of 3-aminopropanal are achieved before the onset of significant cerebral cell damage, and increase in a time-dependent manner with spreading neuronal and glial cell death. Glial cell cultures exposed to 3-aminopropanal undergo apoptosis (LD50 = 160 μM), whereas neurons are killed by necrotic mechanisms (LD50 = 90 μM). The tetrapeptide caspase 1 inhibitor (Ac-YVAD-CMK) prevents 3-aminopropanal–mediated apoptosis in glial cells. Finally, treatment of rats with two structurally distinct inhibitors of polyamine oxidase (aminoguanidine and chloroquine) attenuates brain polyamine oxidase activity, prevents the production of 3-aminopropanal, and significantly protects against the development of ischemic brain damage in vivo. Considered together, these results indicate that polyamine oxidase–derived 3-aminopropanal is a mediator of the brain damaging sequelae of cerebral ischemia, which can be therapeutically modulated.

Elevated N1‐Acetylspermidine Levels in Gerbil and Rat Brains After CNS Injury

“…Recent evidence demonstrated that under certain conditions PAO could directly act on spermine and spermidine to produce putrescine (Ivanova et al, 1998). Our data indicate that the putrescine is largely formed by PAO action on N 1 -acetylspermidine and that the contribution of PAO direct oxidation of spermidine to putrescine appears to be minimal.…”

“…1) and previous studies (Dogan et al, 1999a,b), inhibition of PAO with MDL 72527 significantly attenuated putrescine levels at 1 day after CNS injury. This suggests that the induction of SSAT (Zoli et al, 1996) and PAO (Baudry and Najm, 1994;Hayashi and Baudry, 1995;Ivanova et al, 1998), which convert spermine and spermidine to putrescine, probably is a major pathway accounting for putrescine accumulation at 1 day. These studies did not attempt to correlate SSAT enzymatic activity to N 1 -acetylspermidine levels because the SSAT assay may overestimate N 1 -SSAT activity (Persson and Pegg, 1984;Gerner et al, 1993).…”

“…putrescine (Dempsey et al, 1991;Paschen, 1992a;Kindy et al, 1994;Rao et al, 1995Rao et al, , 1998Henley et al, 1996;Başkaya et al, 1996a,b). These changes correlate with the degree of injury and with neuronal death (Kindy et al, 1994;Henley et al, 1996;Ivanova et al, 1998). Although ODC is considered the rate-limiting enzyme in polyamine biosynthesis, it is not the sole pathway accounting for putrescine levels in tissues (Paschen et al, 1988).…”

Spermine Protects Mice Against Lethal Sepsis Partly by Attenuating Surrogate Inflammatory Markers

“…On one hand, spermine might be protective by attenuating excessive inflammatory response when given at a moderate dose (for example, 10 kg/mL). On the other hand, it might be converted enzymatically by polyamine oxidases into cytotoxic metabolites (for example, 3-aminopropanal), and mediate cytotoxicity through direct chemical modification of cell membrane proteins (35,36). Although the observed dual (both beneficial and injurious) effects of spermine may pose limitations to its clinical use as a potential therapeutic agent, it provides us with a unique tool to elucidate the complex mechanisms underlying the pathogenesis of sepsis.…”

Effect of sub-chronic intraperitoneal administration of aminoguanidine on the memory and hippocampal apoptosis-related genes in diabetic rats

“…Other neuroprotective mechanisms of AG may be related to its free radical scavenging properties (35,39). Also, a number of cellular metabolic pathways about AG neuroprotective functions relate to methylglyoxal (MG) inhibition (40). MG acts as either an endogenous fatal substance (41) or an effective source of ROS (42), which frequently build up in the hippocampal neurons in hyperglycemia (43,44,45).…”