BACKGROUND: Previous studies have shown that propofol enhances proliferation of cultured hippocampal precursor cells in vitro and increases proliferation of cultured hippocampal precursor cells inhibited by corticosterone. Because gamma-aminobutydc acid A (GABA-A) receptor is the functional target for propofol, the proliferative effects of propofol are thought to take place through GABA-A receptor.OBJECTIVE: To determine whether propofol enhances proliferation of rat hippocampal precursor ceils inhibited by corticosterone by upregulating expression of GABA-A receptor.DESIGN, TIME AND SETTING: A comparative, observational, in vitro experiment was performed at the Beijing Institute of Pharmacology and Toxicology from April 2005 to April 2006.MATERIALS: Propofol was purchased from AstraZeneca, Italy; corticosterone was purchased from Sigma, USA; bicuculline was purchased from Alexis, Switzerland.METHODS: Hippocampal precursor cells were isolated from newb Wistar rats and cultured in vitro. The second passage of precursor cells was grouped according to the various drugs added to the culture medium: 0.5 μmol/L propofol; 2.5 pmol/L propofol; 100 μmol/L corticosterone; 10 μmol/L bicuculline; 100 μmol/L corticosterone and 0.5 μmol/L propofol; 100 μmol/L corticosterone and 2.5 μmol/L propofol; 100 μmol/L corticosterone, 10 μmol/L bicuculline, and 0.5 μmol/L propofol;100 μmol/L corticosterone, 10 μmol/L bicuculline, and 2.5 μmol/L propofol; 100 μmol/L corticosterone and 10 μmol/L bicuculline. The cells were cultured for 24 hours with medium containing the respective concentration of drug. The control group consisted of precursor cells absent of drug treatment.MAIN OUTCOME MEASURES: The MTT and ~3H-TdR incorporation assays were used to detect proliferative effects of propofol and bicuculline on cultured rat hippocampal precursor cells inhibited by corticosterone. Immunocytochemistry was used to detect GABA-A receptor expression.Enzyme-linked immunosorbent assay was used to quantify GABA-A receptor expression.RESULTS: Propofol, at a concentration of 0.5 and 2.5 μmol/L, increased proliferation of cultured rat hippocampal precursor cells inhibited by corticosterone, while bicuculline antagonized the effects of propofol (P<0.05 or P<0.01). Corticosterone (100 μmol/L) decreased expression of GABA-A receptor in the hippocampal precursor cells (P<0.05), and GABA-A receptor expression was upregulated when propofol (2.5 μmol/L) was added to the culture medium (P< 0.05).CONCLUSION: Low concentrations of propofol increased expression of GABA-A receptor. These results suggest that GABA-A receptor is involved in increased proliferation of corUsone-inhibited rat hippocampal precursor cells in vitro.