Value of high-performance liquid chromatographic analysis of amino acids in the determination of Panax ginseng radix extract effect in cultured neurons.

The present research describes a reversed-phase high-performance liquid chromatographic (RP-HPLC) method that allows the determination of several amino acids in primary cultured cortical neurons of rats. The concentration of amino acids was determined by using pre-column derivatization with dansyl chloride and UV-diode array detection. Data show that Panax ginseng radix extract (GS) can modulate amino acid release in neurons. The levels of glutamate (Glu), aspartate (Asp), gamma-aminobutyric acid (GABA) and glycine (Gly) in the GS-treated groups were higher than in the non-treated groups dose-dependentwise. In this case, Glu and GABA were the most released amino acids (74.43% +/- 0.97 and 88.41% +/- 4.12 at ginseng dose 0.01 mg/ml after 1h from treatment, respectively). The values obtained in the determination of the analytical parameters (linearity, precision, limit of detection and accuracy) confirm the quality of the method. The average recoveries for intra and inter-day assay (n = 5) were 101.18 and 102.38 for Asp, 99.35 and 98.44 for Glu, 99.59 and 99.66 for Gly, and 100.06 and 100.37 for GABA. These data proved that the method yields accurate results, with RSD lower than 2.2%. The precision of the method was estimated on the basis of RSD of six injections at two different concentrations of amino acids. This technique is useful in studying the GS-mediated modulation of the dynamic equilibrium of amino acids and neurotransmission in neurons.

SNAP, a NO donor, induces cellular protection only when cortical neurons are submitted to some aggression process.

Nitric oxide is a versatile molecule, which plays important physiological and pathological roles. Its protective and toxic actions have been already evidenced in several cell types. However, the protective effect in cortical neurons remains elusive. In this work, we demonstrate that the NO-donor SNAP may induce both neuroprotection and neurotoxicity in this sort of cells. The protective effect of NO was evidenced when cortical neurons were exposed to deleterious conditions, such as serum deprivation. Serum deprivation induces apoptotic cortical neuron death through a caspase-dependent mechanism. Under these conditions, SNAP was able to oppose cell death through both caspase-3 inhibition and/or increase of antiapoptotic protein levels (Bcl-2 and Bcl-x(L)). On the other hand, in a normally serum-supplemented medium, high dose of SNAP behaves as a neurotoxic agent, through a mechanism which involves caspase-3 activation.

[Effect of thioacetamide on the incorporation of 32P into phospholipids of rat liver]. / Efecto de la tioacetamida sobre la incorporación de 32P a fosfolípidos de hígado de rata.

The effect of thioacetamide on rat liver phospholipids biosynthesis was investigated using 32P as precursor. The incorporation of 32P-ortophosphate in the polar lipid fraction and the specific radioactivities of individual phospholipids in the liver fraction and the specific radioactivities of individual phospholipids in the liver of control rats and rats treated with thioacetamide were determined 75 min after intraperitoneal administration of 32P-ortophosphate. Intraperitoneal injection of thioacetamide (daily dose of 100 mg/kg body weight) in male Wistar rats resulted in an increase of 32P incorporation in the over-all phospholipids, after 8 doses administration and a significant decrease during the chronic intoxication. Specific activity of phosphatidylcholine decreased and a parellel increase in specific radioactivity of lisophosphatidylcholine was found after three days of thioacetamide treatment. There was also observed a marked increase in specific radioactivity of sphingomyelin, which could be due to a stimulation of CDP-choline: ceramide cholinephosphotransferase reaction with subsequent diminution of the rate of phosphatidylcholine synthesis via the CDP-amine pathway (involving cytidine diphosphocholine).