Ethanol inhibited growth hormone receptor-mediated endocytosis in primary mouse hepatocytes

Abstract Objectives Growth hormone (GH) exhibits various essential physiological functions, which are exerted by its binding to growth hormone receptor (GHR). Ethanol has been demonstrated to have an impact on GH’s biological activity. Nevertheless, mechanism underlying the regulation of the biological activity of GH by ethanol have yet to be fully elucidated. Methods This study utilized an indirect immunofluorescence assay to identify GHR expression in mouse hepatocytes. Western blot was used to determine the impact of ethanol on GH-induced intracellular signalling. Indirect immunofluorescence and colocalization experiments were used to determine the effect of ethanol on GH-GHR’s nuclear localization and endocytosis. Results GHR was primarily localized in the cell membrane and cytoplasm. The phosphorylation levels of JAK2 and STAT1/3/5 were markedly lowered after treatment with ethanol. On this basis, we further explored the mechanism underlying the regulation of GH biological activity by ethanol from the perspective of cell internalization. We found that the nuclear translocation of GH-GHR was inhibited when treated with ethanol. In addition, the results of colocalization analyses revealed that ethanol inhibited GHR-mediated nuclear translocation may mainly by inhibiting caveolin-dependent endocytosis. Conclusions Our study showed that ethanol inhibits GH signaling ability in a time-dependent manner. Ethanol could inhibit the nuclear localization of GH-GHR, which may be linked to the inhibition of the interaction between GHR and caveolin. The combined effect of these factors downregulated the GH-GHR signal. This study laid a foundation for further exploring the mechanism that the effects of ethanol on GH biological activity.