OBJECTIVETo elucidate the effect of the low dosage endotoxin damage on the expression of the organic cation transporter 1 (OCT1) mRNA in hepatocytes and make an approach to the probable effect of dexamethasone on the expression of the OCT1 mRNA after endotoxin damage.

METHODS(1) The endotoxin damage model was established in rats; (2) The change of the expression of OCT1 mRNA in hepatocytes after endotoxin damage was observed by in situ hybridization method; (3) The change of the ultra structure of hepatocytes after endotoxin damage was observed with the electron microscope; (4) Dexamethasone was injected intraperitoneally before endotoxin damage in order to determine the influence of dexamethasone on the expression of OCT1 mRNA after endotoxin treatment.

RESULTSThe expression of OCT1 mRNA decreased until 16 hours (0.5745+/-0.012, P<0.01) after endotoxin treatment and then increased after this time point, which was still lower than the normal control; The expression of OCT1 mRNA in rat hepatocytes increased at each time point after endotoxin damage with dexamethasone treatment. It was highest at 16 hours (0.6327+/-0.007, P<0.01) after endotoxin damage, but it was still lower than that of the normal control.

CONCLUSIONEndotoxin could repress the expression of OCT1 mRNA even before the low dosage endotoxin inducing serious damage to the structure of hepatocytes; Dexamethasone could not induce the expression of OCT1 mRNA in normal hepatocytes, but could lighten the repression of endotoxin on the expression of OCT1 mRNA. And then the expression of OCT1 mRNA could increase at some extent after endotoxin damage with dexamethasone treatment.