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Effects of Nerotransmitters on the Proliferation of Human Hepatocytes

Objective To explore the effects and mechanism of autonomic nervous control on the proliferation of human hepatocytes. And to examine the cellular localization of some related receptors expression in human hepatocytes. MethodsNorepinephrine (NE), and its agonist, antagonist, acetylcholine (Ach), and its antagonist have been added to human hepatocyte line L02 and hepatoma cell line Bel7402. Modified MTT assay was employed to test the effects of them on the proliferation of the two cell lines at 4 h, 24 h, 48 h and 72 h. Immuocytochemical staining was used to examine the cellular localization of alpha1Badrenoceptor (α1BAR), β2AR and epidermal growth factor receptor (EGFR) expression in human hepatocyte line L02. ResultsNE potentiated the proliferation of human hepatocyte and hepatoma cell, which was enhanced significantly with dose increased. The proliferative rate of 4 h were higher than that of the other time points (P＜0.05). There were no significant differences between the group of NE combined with propanolol and the group of NE alone. Metaproterenol had no significant effect. Ach significantly inhibited the proliferation of human hepatocyte. Its effect was enhanced with dose increased. Atropine significantly attenuated the inhibitory effect of Ach at 24 h and 48 h (P＜0.05). Scoline alone inhibited hepatocyte proliferation at 24 h, 48 h and 72 h (P＜0.05, P＜0.01). In immunocytochemical staining, there were positive responses to α1BAR, β2AR and EGFR in all cultures. It was observed that the responses to α1BAR, β2AR and EGFR were mainly both cytoplasmic and cell membrane localized. Conclusion NE, the sympathetic neurotransmitter, acts via α1BAR potentiate the proliferation of human hepatocyte and hepatoma cell in the presence of serum. Ach, the vagus neurotransmitter acting via mAchR and nAchR inhibits hepatocyte proliferation.