Surrogate Markers of Gamma-hydroxybutyrate (GHB) exposure in cell lines

Asia Abdullah, Elizabeth Ellis. Strathclyde Institute of Pharmacy and Biomedical Sciences, 161 Cathedral street, Hamnet wing 501, Glasgow G4 0RE, UK.

Gamma hydroxybutyric acid (GHB) is an endogenous neurotransmitter found in the brain in low concentrations. The abuse of GHB, especially in date rape sexual assaults has increased in recent years. GHB has a rapid rate of metabolism that causes it to disappear meaning criminal cases are often difficult to prosecute. This study is aimed at extending the window of detection of GHB beyond 12 hours by measuring the GHB-dependent changes in gene expression. In previous study in mouse, a single dose 1g/kg GHB caused upregulation of mRNA encoding epiregulin and Phosphoprotein Enriched in Astrocytes of 15 KDa (PEA-15) in blood (Larson et al, 2007). In this study, the effect of GHB exposure for 24 hours was investigated in three human cell lines (human astrocytoma 1321N1, human neuroblastoma SH-SY5Y and human monocytic leukaemia TH-P1 cells). GHB treatment was not significantly toxic to these cells. Cells were treated with between 1 µM and 900 µM GHB for 24 hours and changes in epiregulin and PEA-15 expression levels were examined. Epiregulin expression was increased by 6.2-fold in 1321N1 cells after treatment with 1 µM GHB and by 5.2-fold in THP-1 cells after treatment with 10 µM GHB. However epiregulin expression disappeared in SHSY5Y after GHB treatment. PEA-15 level increased in 1321N1 and SHSY5Y cells by 4.2 and 3.7 fold respectively after treatment with 100 µM GHB and increased in THP-1 cells by 40.8 fold after treatment with 10 µM GHB. The results show that GHB induces changes in gene expression in all three cell lines used and this information may be useful in finding markers for GHB exposure in forensic toxicology.

Larson SJ, Putnam EA, Schwanke CM, Pershouse MA. (2007) J Anal Toxicol. 31:15-22.