Piracetam inhibits the lipid-destabilising effect of the amyloid peptide Abeta C-terminal fragment

Neuroprotective effect of piracetam-loaded magnetic chitosan nanoparticles against thiacloprid-induced neurotoxicity in albino rats

Thiacloprid (TH) is a neurotoxic agricultural insecticide and potential food contaminant. The purpose of this study was to investigate the relationship between TH exposure and memory dysfunction in rats, as well as the potential protective effect of piracetam and piracetam-loaded magnetic chitosan nanoparticles (PMC NPs). Rats were divided into five equal groups (six rats/group). The control group received saline. Group II was treated with PMC NPs at a dose level of 200 mg/kg body weight (Bwt); Group III was treated with 1/10 LD₅₀ of TH (65 mg/kg Bwt); Group IV was treated with TH (65 mg/kg Bwt) and piracetam (200 mg/kg Bwt); Group V was co-treated with TH (65 mg/kg Bwt) and PMC NPs (200 mg/kg Bwt). All animal groups were dosed daily for 6 weeks by oral gavage. Footprint analysis, hanging wire test, open field test, and Y-maze test were employed to assess behavioral deficits. Animals were euthanized, and brain tissues were analyzed for oxidative stress biomarkers, proinflammatory cytokines, and gene expression levels of glial fibrillary acidic protein (GFAP), amyloid-beta precursor protein (APP), B-cell lymphoma 2 (Bcl-2), and caspase-3. Brain and sciatic nerve tissues were used for the evaluation of histopathological changes and immunohistochemical expression of tau protein and nuclear factor kappa B (NF-κB), respectively. The results revealed that TH-treated rats suffered from oxidative damage and inflammatory effect on the central and peripheral nerves. The administration of PMC NPs considerably protected against TH-induced neuronal damage, increased antioxidant enzyme activity, decreased inflammatory markers, and improved behavioral performance than the group treated with piracetam. The neuroprotective effect of PMC NPs was mediated through the inhibition of GFAP, APP, caspase-3, Tau, and NF-κB gene expression with induction of Bcl-2 expression. In conclusion, TH could induce oxidative stress, inflammatory and neurobehavior impairment in rats. However, PMC NPs administration markedly mitigated TH-induced brain toxicity, possibly via oxidative and inflammatory modulation rather than using piracetam alone.

Rapid determination of piracetam in human plasma and cerebrospinal fluid by micellar electrokinetic chromatography with sample direct injection

A simple micellar electrokinetic chromatography (MEKC) method with UV detection at 200 nm for analysis of piracetam in plasma and in cerebrospinal fluid (CSF) by direct injection without any sample pretreatment is described. The separation of piracetam from biological matrix was performed at 25 degrees C using a background electrolyte consisting of Tris buffer with sodium dodecyl sulfate (SDS) as the electrolyte solution. Several parameters affecting the separation of the drug from biological matrix were studied, including the pH and concentrations of the Tris buffer and SDS. Under optimal MEKC condition, good separation with high efficiency and short analyses time is achieved. Using imidazole as an internal standard (IS), the linear ranges of the method for the determination of piracetam in plasma and in CSF were all between 5 and 500 microg/mL; the detection limit of the drug in plasma and in CSF (signal-to-noise ratio=3; injection 0.5 psi, 5s) was 1.0 microg/mL. The applicability of the proposed method for determination of piracetam in plasma and CSF collected after intravenous administration of 3g piracetam every 6h and oral administration 1.2g every 6h in encephalopathy patients with aphasia was demonstrated.

Lipid-destabilising properties of a peptide with structural plasticity

The Chameleon peptide (Cham) is a peptide designed from two regions of the GB1 protein, one folded as an alpha-helix and the other as a beta structure. Depending on the environment, the Cham peptide adopts an alpha or a beta conformation when inserted in different locations of GB1. This environment dependence is also observed for tilted peptides. These short protein fragments, able to destabilise organised system, are mainly folded in beta structure in water and in alpha helix in a hydrophobic environment, like the lipid bilayer. In this paper, we tested whether the Cham peptide can be qualified as a tilted peptide. For this, we have compared the properties of Cham peptide (hydrophobicity, destabilising properties, conformation) to those of tilted peptides. The results suggest that Cham is a tilted peptide. Our study, together the presence of tilted fragments in transconformational proteins, suggests a relationship between tilted peptides and structural lability.

Piracetam: a review of pharmacological properties and clinical uses

Piracetam, a derivative of the neurotransmitter gamma-aminobutyric acid (GABA), has a variety of physiological effects that may result, at least in part, from the restoration of cell membrane fluidity. At a neuronal level, piracetam modulates neurotransmission in a range of transmitter systems (including cholinergic and glutamatergic), has neuroprotective and anticonvulsant properties, and improves neuroplasticity. At a vascular level, it appears to reduce erythrocyte adhesion to vascular endothelium, hinder vasospasm, and facilitate microcirculation. This diverse range of physiological effects is consistent with its use in a range of clinical indications. Its efficacy is documented in cognitive disorders and dementia, vertigo, cortical myoclonus, dyslexia, and sickle cell anemia. While high doses are sometimes necessary, piracetam is well tolerated.

Fusogenic Alzheimer's peptide fragment Abeta (29-42) in interaction with lipid bilayers: secondary structure, dynamics, and specific interaction with phosphatidyl ethanolamine polar heads as revealed by solid-state NMR

The interaction of the native Alzheimer's peptide C-terminal fragment Abeta (29-42), and two mutants (G33A and G37A) with neutral lipid bilayers made of POPC and POPE in a 9:1 molar ratio was investigated by solid-state NMR. This fragment and the lipid composition were selected because they represent the minimum requirement for the fusogenic activity of the Alzheimer's peptide. The chemical shifts of alanine methyl isotropic carbon were determined by MAS NMR, and they clearly demonstrated that the major form of the peptide equilibrated in membrane is not in a helical conformation. (2)H NMR, performed with acyl chain deuterated POPC, demonstrated that there is no perturbation of the acyl chain's dynamics and of the lipid phase transition temperature. (2)H NMR, performed with alanine methyl-deuterated peptide demonstrated that the peptide itself has a limited mobility below and above the lipid phase transition temperature (molecular order parameter equal to 0.94). MAS (31)P NMR revealed a specific interaction with POPE polar head as seen by the enhancement of POPE phosphorus nuclei T(2) relaxation. All these results are in favor of a beta-sheet oligomeric association of the peptide at the bilayer interface, preferentially recruiting phosphatidyl ethanolamine polar heads.