Protective Effect of Low Dose of Methamphetamine on The Amount of Extracellular Glutamine in Primary Fetal Human Astrocytes Induced by Amyloid Beta.

Objective: Change in astrocytes is one of the first pathological symptoms of Alzheimer's disease (AD). Understanding the signaling pathways in astrocytes can be a great help in treating of AD. This study aimed to investigate signaling pathway relations between low dose of methamphetamine (METH), the apoptosis, cell cycle, and glutamine (Gln) pathways in the activated astrocyte. Materials and Methods: In this experimental study, the activated astrocyte cells were exposed to a low dose of METH (12.5 µM) which was determined by Thiazolyl blue tetrazolium bromide (MTT) method. The groups were: group 1 cells with Aß, group 2 cells with METH, group 3 cells with METH after 24 hours of adding Aß (Aß+METH, treated group), group 4 cells with Aß after 24 hours of adding METH (METH+Aß, prevention group), and group 5 as the control. The Gln was assayed by high-performance liquid chromatography (HPLC), and also the apoptosis, and cell cycle and BAX, BCL-X expression was evaluated. Results: The amount of Gln was increased, and the value of late and early apoptosis was reduced in the treatment groups, and necrosis is decreased in the prevention group (group 4 compared to group 1). Moreover, it was revealed through cell cycle analysis that G2 in group 4 was reduced compared to group 1 and the expression of BAX, BAX/ BCL-X, and BCL-X in group 3 and group 4, was decreased and increased, respectively compared to group 1. Conclusion: These findings suggest that perhaps a non-toxic dosage of METH (low dose) can reduce the amount of apoptosis and BAX expression and increase the expression of BCL-X. Furthermore, the cells are arrested in the G2 phase and can raise the amount of extracellular glutamine, which has a protective role in neuron cells. These findings may provide a new perspective to design a new drug with less toxic results.

Alteration of gene expression in reactive astrocytes induced by Aß1-42 using low dose of methamphetamine.

BACKGROUND: Alzheimer's disease (AD) is a degenerative brain disorder. Due to the relationship between the functional loss of astrocytes and AD, the present study aims to evaluate the effects of the low dose of methamphetamine (METH) on primary fetal human astrocytes under a stress paradigm as a possible model for AD. METHODS AND RESULTS: The groups in this study included Aß (Group 1), METH (Group 2), Aß + METH (METH after adding Aß for 24 h) (Group 3 as treated group), METH + Aß (Aß after adding METH for 24 h) (Group 4 as prevention group), and control group. Then, the gene expression of Bax, Bcl-X, PKCα, GSK3ß, and Cdk5 was evaluated. In addition, phosphorylated tau, p-GSK3ß, GSK3ß, and GSK3α proteins were assessed by western blotting. Further, cell cycle arrest and apoptosis were checked by flow cytometry and Hoechst staining. Based on the results, the expression of GSK3ß, Cdk5, and PKCα genes decreased in the prevention group, while GSK3ß and Cdk5 were amplified in the treatment group. Furthermore, the level of GSK3α and GSK3ß proteins in the treatment group increased, while it decreased in the prevention group. Additionally, a decrease occurred in the percentage of necrosis and early apoptosis in the treatment and prevention groups. The results of the cell cycle indicated that G1 increased, while G2 decreased in the prevention group. CONCLUSION: The pure form of METH can prevent from activating GSK-3ß and CdK-5, as well as enhanced activity of PKCα to inhibit phosphorylated tau protein. Therefore, a low dose of METH may have a protective effect or reducing role in the pathway of tau production in reactive astrocytes.

Structural characterization of recombinant streptokinase following recovery from inclusion bodies using different chemical solubilization treatments.

Circular dichroism (CD) in far-UV region was employed to study the extent of changes occurred in the secondary structures of recombinant streptokinase (rSK), solubilized from inclusion bodies (IBs) by different chemicals and refolded/purified by chromatographic techniques. The secondary structure distribution of rSK, obtained following different chemical solubilization systems, was varied and values in the range of 12.4-14.5% α-helices, 40-51% ß-sheets and 35.5-48.3% turns plus residual structures were found. With reducing the concentration of chemicals during IB solubilization, the content of turns plus random coils was diminished and simultaneously the amounts of α- and ß-sheets were increased. These changes in the secondary structures would lower the hydrophobicity along with the chance of protein aggregation and expose the hydrophilic regions of the protein. Therefore, these alterations in the secondary structures, occurred following efficient IBs solubilization by low concentration of chemicals, could be related to enhancement in rSK biological potency previously observed.