Objective  To evaluate the effect of γ-aminobutyric acid (GABA) and its receptors upon the proliferation of CD8⁺T cells.

  Methods  The splenic CD8⁺T cells of Balb/c mice were obtained by CD8⁺T cell magnetic bead sorting kit. Under the effect of CD3/CD28-activated magnetic bead, CD8⁺T cells were stimulated by GABA of different concentrations. 5-bromo-2-deoxyuridine (BrdU) labeling and flow cytometry were performed to detect the proliferation of CD8⁺T cells. The expression levels of GABA-A and GABA-B receptor before and after CD8⁺T cell activation were compared by fluorescent quantitative real-time polymerase chain reaction (PCR).

  Results  Flow cytometry result revealed that GABA could inhibit the proliferation of activated CD8⁺T cells, manifested as significant decrease in the quantity of CD152⁺CD8⁺T cells. Fluorescent quantitative real-time PCR demonstrated that GABA-A receptor subtypes α2, α6 and GABA-B receptor subtype 1a were expressed only when the CD8⁺T cells were activated. After CD8⁺T cell activation, the quantity of GABA-A receptor subtypes α3, α5, β2, β3, γ1, γ2 and θ were significantly increased, whereas the quantity of GABA-B2R and GABA-B1b did not significantly differ before and after CD8⁺T cell activation.

  Conclusions  GABA can suppress the proliferation of activated CD8⁺T cells. The activation of CD8⁺T cells is regulated by GABA receptors. However, the underlying mechanism remains to be elucidated.