Abstract
BACKGROUND: Liposomes are concentric lipid vesicles that allow a sustained release of entrapped substances. GABA (γ-aminobutyric acid) is the most prevalent inhibitory neurotransmitter in the central nervous system. NEW METHOD: Using GABA-containing liposomes (GL) prepared by the freeze-thawing method, we determined the effect of sustained release of GABA on expression of neuronal nitric oxide synthase (nNOS) and GABA(A) receptor (GABA(A)R) in an in vitro neuronal model. RESULTS: Neuronal cell line NG108-15 treated with different doses of GL during 24h showed an increase in expression of GABA(A)R (54 and 50% with 10 and 20ng doses, respectively) and nNOS (138, 157 and 165% with 20, 50 and 100ng doses, respectively) compared with cells treated with empty liposomes (EL). Additionally, cells treated with 50ng of GL showed an increase in GABA(A)R (23%) after 1h followed by an increase in nNOS (55, 46 and 55%) at 8, 12 and 24h time points, respectively. Immunofluorescence experiments confirmed an increase in nNOS (134%) and basal intracellular levels of nitric oxide (84%) after GL treatment. Further, treatment of cells with GL showed a decrease in expression of a protein inhibitor of nNOS (PIN) (26, 66 and 57% with 20, 50 and 100ng doses respectively) compared with control. COMPARISON WITH EXISTING METHODS: This is first demonstration for the development of GL that allows sustained slow release of this neurotransmitter. CONCLUSION: These results suggest that a slow release of GABA can change the expression of nNOS possibly via alteration in PIN levels in neuronal cells.