Lysine induces lipid and protein damage and decreases reduced glutathione concentrations in brain of young rats

Abstract

The present work investigated the in vitro effects of lysine on important parameters of oxidative stress in cerebral cortex of young rats. Our results show that lysine significantly induced lipid peroxidation, as determined by increase of thiobarbituric acid-reactive substances and chemiluminescence levels, as well as protein oxidative damage since carbonyl formation and sulfhydryl oxidation were enhanced by this amino acid. Furthermore, the addition of free radical scavengers significantly prevented lysine-induced lipid oxidative damage, suggesting that free radicals were involved in this effect. Lysine also significantly diminished glutathione levels in cortical supernatants, decreasing, therefore, the major brain antioxidant defense. Finally, lysine markedly oxidized a glutathione commercial solution in a medium devoid of brain supernatants, indicating that it behaved as a direct acting oxidant. The present data indicate that lysine induces oxidative stress in cerebral cortex of young rats. Therefore, it is presumed that this pathomechanism may be involved at least in part in the neurological damage found in patients affected by disorders with hyperlysinemia.

Hepatoprotective, cardioprotective, and renal-protective effects of organic and conventional grapevine leaf extracts (Vitis labrusca var. Bordo) on Wistar rat tissues

“…Tissues were weighed and kept chilled until homogenization, which was performed using a ground glass type Potter-Elvejhem homogenizer in 1.5% KCl. The homogenates were centrifuged at 800 g for 10 min at 4 • C, the pellet was discarded and the supernatants were immediately used (Seminotti et al 2008). Kidney, liver and heart supernatants were treated with grape leaf extracts (5 mg/mL) for one hour, then 10 mM hydrogen peroxide (H 2 O 2 ) was added, and the mixture was incubated for half an hour.…”

Neurochemical Evidence that Lysine Inhibits Synaptic Na+,K+-ATPase Activity and Provokes Oxidative Damage in Striatum of Young Rats In vivo

“…However, no differences in these parameters were found 12 h after the amino acid injection. Considering our previous in vitro results indicating that antioxidant scavengers were able to totally prevent the lipid oxidation elicited by Lys in cerebral cortex [18], we investigated the effect of i.p. pre-treatment of melatonin, a-tocopherol and ascorbic acid or creatine for 3 days, once a day, on Lys-induced increase of TBA-RS and decrease of GSH levels 2 h after Lys injection.…”

“…We have previously demonstrated that Lys induces oxidative stress [18] and compromises brain bioenergetics [19] in cortex of young rats in vitro. In the present study we investigated whether Lys in vivo intrastriatal administration could disturb mitochondrial homeostasis by examining important parameters of energy metabolism and oxidative stress.…”

“…Changes in membrane fluidity due to Lys are unlikely since they usually occur due to the incorporation of hydrophobic substances into the plasma membrane altering the associations between lipids and the enzyme [47,51,52]. On the other hand, considering that Lys induces oxidative stress in vitro [18], it is possible that the reduction of this enzymatic activity caused by Lys could occur through oxidative damage.…”

“…Previous studies have shown that exposure of cerebral cortex preparations to Lys leads to oxidative stress [18] and bioenergetics dysfunction [19], suggesting that Lys is neurotoxic. In the present study, we investigated the influence of intrastriatal administration of Lys to young rats on relevant parameters of energy homeostasis and oxidative stress, because patients affected by inherited metabolic disorders with hyperlysinemia usually present basal ganglia abnormalities, besides cortical atrophy [20][21][22][23].…”