Lakatos PP, Vincze I, Nyariki N, Bagaméry F, Tábi T, Szökő É. The effect of L-theanine and S-ketamine on d-serine cellular uptake.
BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020;
1868:140473. [PMID:
32574765 DOI:
10.1016/j.bbapap.2020.140473]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 05/12/2020] [Accepted: 06/13/2020] [Indexed: 11/30/2022]
Abstract
Decreased extracellular level of d-Serine (D-Ser), a co-agonist of the N-methyl-d-aspartate (NMDA) receptors was connected to receptor hypofunction in the brain and the related deficit of cognitive functions. Extracellular D-Ser concentration is modulated by ASCT neutral amino acid transporters. L-Theanine (L-Tea), a neutral amino acid component of green tea was reported to improve cognitive functions. We thus intended to investigate the possible inhibitory effect of L-Tea on the D-Ser uptake of SH-SY5Y neuroblastoma cells, which was previously found as a good model of D-Ser transport into astrocytes. Cells were incubated with D-Ser and various concentrations of L-Tea or the reference compound S-ketamine (S-Ket). The effect on the uptake was assessed by measuring the intracellular D-Ser concentration using a capillary electrophoresis - laser induced fluorescence detection method. L-Tea competitively inhibited D-Ser uptake into SH-SY5Y cells with an IC50 value of 9.68 mM. Having previously described as an inhibitor of ASCT-2 transporter, S-Ket was intended to be used as a positive control. However, no acute inhibition of D-Ser transport by S-Ket was observed. Its long-term effect on the transport was also examined. No significant difference in D-Ser uptake in control and S-Ket-treated cells was found after 72 h treatment, although the intracellular D-Ser content of the 50 μM S-Ket pre-treated cells was significantly higher. L-Tea was found to be a weak competitive inhibitor of the ASCT transporters, while S-Ket did not directly affect D-Ser uptake or modify the uptake kinetics after a long-term incubation period.
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