Protective effect of alpha-lipoic acid on cypermethrin-induced oxidative stress in Wistar rats.

Cypermethrin (CY), a class II pyrethroid pesticide, is globally used to control insects in the household and in agriculture. Despite beneficial roles, its uncontrolled and repetitive application leads to unintended effects in non-target organisms. In light of the relevant anti-oxidant properties of alpha-lipoic acid (ALA), in the work described herein we tested the effect of a commercially available ALA formulation on cypermethrin CY)-induced oxidative stress in Wistar rats. The rats were orally administered with 53.14 mg/kg of ALA and 35.71 mg/kg of CY for 60 days. The treatment with CY did not induce changes in either locomotor activities or in body weight. Differences were observed on superoxide dismutase (SOD), catalase (CAT) and lipid peroxidation that were re-established by ALA treatment at similar levels of the placebo group. Furthermore, ALA formulation increased glutathione (GSH) level and glutathione peroxidase (GPx) activity. Because of the widespread use of CY, higher amounts of pesticide residues are present in food, and a diet supplementation with ALA could be an active free radical scavenger protecting against diseases associated with oxidative stress.

Effects of trimethyltin on hippocampal dopaminergic markers and cognitive behaviour.

The triorganotin compound trimethyltin (TMT) is a highly toxic molecule which has a great impact on human health. The aim of this study was to investigate the specific alteration of dopamine receptors and transporters in the hippocampus of TMT-treated rats. The TMT-treated group showed impaired spatial reference memory in a Morris water maze task compared to the control group, whereas memory consolidation tested 24 hours after the last training session was preserved. In the open field, TMT-treated rats showed a decrease in time spent in rearing episodes reflecting a lower interest to explore a novel environment. In the hippocampal area of the TMT-treated group, we observed a reduction in neuronal viability accompanied by a significant decrease in the expression of the dopamine receptors (D1 and D2), and dopamine transporters (DAT, VMAT1 and VMAT2). A less pronounced reduction was observed for D3 and D5 while D4 did not change. These data were confirmed by RT-PCR analysis. The present study on TMT-induced neurodegeneration highlights the link between hippocampal asset of dopamine receptors and transporters and the impaired performance of rats in a spatial reference memory task.

Ibuprofen and lipoic acid codrug 1 control Alzheimer's disease progression by down-regulating protein kinase C ε-mediated metalloproteinase 2 and 9 levels in ß-amyloid infused Alzheimer's disease rat model.

Alzheimer's disease (AD) commonly begins with loss of recent memory and is associated to pathological and histological hallmarks such as ß amyloid plaques, neural tangles (NFT), cholinergic deficit, extensive neuronal loss and synaptic changes in the cerebral cortex and hippocampus. The amyloid cascade hypothesis implies the activity of ß, γ secretases which mediate the cleavage of APP (Amyloid Precursor Protein), the formation of amyloidogenic Aß fragment (1-42), which compacts into amyloid plaques, while the cleavage by α secretase of APP, within the Aß segment (non-amyloidogenic processing) forms sAPP and prevents the formation of Aß. Among the proteases which have Aß-degrading activity, Metalloproteinase (MMP) 2, disclosing ß secretase-like activity, is included, while MMP9 seems to contribute to neuronal death. In addition, since intracellular signaling protein kinase C (PKC) can control either directly α secretase or indirectly through regulation of ERK1/2, preventing the formation of ß amyloid, created by ß and γ secretase, and prolonging the life span of Alzheimer's disease mutant mice, here we show the effects exerted by new codrug 1 on PKC ε-mediated MMP2 and MMP9 levels regulation in Aß (1-40) infused rat cerebral cortex. Interestingly codrug 1, lowering metalloproteinases expression via PKC ε down-modulation, seems to control Alzheimer's disease induced cerebral amyloid deposits, neuronal death and, lastly, behavioral deterioration.

Ibuprofen and lipoic acid diamide as co-drug with neuroprotective activity: pharmacological properties and effects in beta-amyloid (1-40) infused Alzheimer's disease rat model.

Both oxidative stress and inflammation are elevated in brains of Alzheimer's disease patients, but their pathogenic significance still remains unclear. Current evidence support the hypothesis that non-steroidal anti-inflammatory drugs (NSAIDs) and antioxidant therapy might protect against the development of Alzheimer's disease, and ibuprofen has the strongest epidemiological support. In the present work our attention was focused on (R)-alpha-lipoic acid considered as a potential neuroprotective agent in Alzheimer's disease therapy. In particular, we investigated a new co-drug (1) obtained by joining (R)-alpha-lipoic acid and ibuprofen via a diamide bond, for evaluating its potential to antagonize the deleterious structural and cognitive effects of beta-amyloid (1-40) in an infused Alzheimer's disease rat model. Our results indicated that infusion of beta-amyloid (1-40) impairs memory performance through a progressive cognitive deterioration; however, ibuprofen and co-drug 1 seemed to protect against behavioural detriment induced by simultaneous administration of beta-amyloid (1-40) protein. The obtained data were supported by the histochemical findings of the present study: beta-amyloid protein was less expressed in 1-treated than in ibuprofen and (R)-alpha-lipoic acid alone-treated cerebral cortex. Taken together, the present findings suggest that co-drug 1 treatment may protect against the cognitive dysfunction induced by intracerebroventricular infusion of beta-amyloid (1-40) in rats. Thus, co-drug 1 could prove useful as a tool for controlling Alzheimer's disease-induced cerebral amyloid deposits and behavioural deterioration.

The primary role of glutathione against nuclear DNA damage of striatum induced by permethrin in rats.

Pyrethroids are one of the most widely used class of insecticides and their toxicity is dominated by pharmacological actions upon the CNS. This study reports as the subchronic treatment (60 days) with permethrin (PERM) (1/10 of LD(50)) induced nuclear DNA damage in rat striatum cells. Comet assay outcomes showed that PERM produced single- and double-strand breaks in striatum cells, the DNA damage was not related to oxidation at pyrimidine and purine bases. Vitamin E (280 mg/kg body weight/day) and vitamin E+coenzyme Q(10) (10 mg/kg/3 ml) supplementation could protect PERM treated rats against nuclear DNA damage. With the aim to evaluate the cause of nuclear DNA damage observed in striatum of rat treated with PERM, in vitro studies on striatum submitochondrial particles (SMPs) and on striatum cells treated with 10 muM PERM alone or plus 16 or 32 nM GSH were performed. SMPs incubated with PERM showed a decrease in superoxide anion release from the electron transport chain by inhibition of mitochondrial complex I. The effect could be related to the decrease of membrane fluidity measured in the hydrophilic-hydrophobic region of the mitochondrial membrane. This result discarded the involvement of the mitochondrial reactive oxygen species in the nuclear DNA damage. On the contrary, GSH played a crucial role on striatum since it was able to protect the cells against nuclear DNA damage induced by PERM. In conclusion our outcomes suggested that nuclear DNA damage of striatum cells was directly related to GSH depletion due to PERM insecticide.

A strategy for identifying novel, mechanistically unique inhibitors of topoisomerase I.

While the design of molecules that inhibit or antagonize the functions of specific macromolecules is now well precedented, in many cases the structural information requisite to the design process is lacking. The tools of molecular biology can now furnish the target macromolecules for use in mechanism-based exploration; highly defined assays can be devised based upon the known biochemistry of these macromolecules to permit the discovery of novel inhibitors or antagonists present in chemical collections. Presently, we describe a set of assays directed toward the discovery of novel inhibitors of eukaryotic topoisomerase I, an enzyme critical to maintenance of chromosomal DNA topology and therefore essential for normal replication and transcription. The identification of chebulagic acid as an extraordinarily potent and mechanically novel inhibitor of topoisomerase I illustrates the potential of this approach.