| 摘要 |
Gamma aminobutyric acid (GABA) is a potent inhibitory neurotransmitter that binds to hetero-oligomeric receptors in the mammalian brain. In a previous study, we documented specific GABA binding to isolated rat hepatocytes which resulted in inhibition of hepatocyte proliferation. The purpose of the present study was to define the nature of hepatic GABA A receptors and document thei r expression during rapid liver growth (post-partial hepatectomy). Polymerase chain reactions (PCR) with gene-specific primers derived from published sequences were performed with marathon-ready human and rat liver cDNA. Two GABA A receptor subunit types (.beta.3 and .epsilon.) were expressed in the human liver and one (.beta.3) in the rat liver. PCR amplification of the human GABA A receptor .beta.3 subunit produc ed a single product (m.w. 53-59 kDa). In the case of the .epsilon. subunit, two PCR products were identified. Following partial hepatectomy, GABA A receptor .beta.3 subunit expression inversely correlated with regenerative activity (r= -0.527, p=0.006). In conclusion, these results indicate that in the human liver, GABA A receptors consist of the .beta.3 and .epsilon. subunit types whereas in the rat liver, only the .beta.3 subunit type is expressed. The results also support the hypothesis that GABAergicactivity serves to maintai n hepatocytes in a quiescent state.
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