OBJECTIVETo study the effects of sinomenine (Sin) on cell proliferation, intracellular expression of cyclooxygenase-2 (COX-2), and production of PGE2 in lipopolysaccharide-induced PC-12 cells, To explore the Sin's mechanism on nerve cell.

METHODPC-12 cells were cultured with nerve growing factors (NGF), and pretreated with Sin at various concentrations (0, 3 x 10(-6), 30 x 10(-6), 150 x 10(-6) mol x L(-1)) for 2 hours, then with or without stimulation of lipopolysaccharide (LPS). The proliferation activity of PC-12 cells was determined by 3H-TdR incorporation, and the production of PGE2 in culture supernatants of PC-12 cells was detected with competitive ELISA. Expression of COX-2 mRNA in PC-12 cells was analyzed by semi-quantitative RT-PCR, and expression of COX-2 protein was estimated by Western blot method and cellular enzyme immunoassay. Nuclear factor-kappa B (NF-kappaB) activity in whole-cell extract of PC-12 cells was also measured by an ELISA-based method.

RESULTThe data showed that Sin down-regulated the expression of COX-2 mRNA and protein, and reduced the production of PGE2 in the LPS-stimulated PC-12 cells which correlated with Sin's concentrations positively. In addition, NF-kappaB activity in LPS-stimulated cells was suppressed significantly by Sin. No inhibition of proliferation of PC-12 cells due to Sin treatment was observed.

CONCLUSIONSin mediates the down-regulation of expression of COX-2 and production of induced PGE2 in PC-12 cells by suppressing the activity of NF-kappaB.