OBJECTIVETo investigate the potential therapeutic properties of the endogenous cannabinoid N-arachidonic acid aminoethanols (anandamide, AEA) in liver fibrosis by observing its affects on proliferation of and expression of phosphorylated-Erk (pErk) in primary hepatic stellate cells (HSCs) from a mouse model of schistosome-induced liver fibrosis.

METHODSThe schistosome-induced liver fibrosis model was established by attaching cercaria to the skin on the ventral side of the mouse and allowing infection to occur via direct penetration. Six weeks later, the model was confirmed by pathological analysis of liver, with Masson trichrome staining showing collagen fiber deposition around the blood vessels and hematoxylin-eosin staining showing eosinophilic granuloma formation. Primary HSCs were isolated by discontinuous density gradient centrifugation, confirmed by immunofluorescence detection of double-staining for a-smooth muscle actin and desmin (95% purity), and cultured in the presence of absence of various concentrations of AEA. Proliferative ability was evaluated by MTT assay and the expression of pErk was observed by Western blotting.

RESULTSAEA treatment inhibited the proliferation of the primary HSCs in a concentration-dependent manner (AEA: 5 mumol/L, inhibition: 7.68%; 10 mumol/L, 11.65%; 20 mumol/L, 14.70%; 40 mumol/L, 15.07%; 60 mumol/L, 18.18%; 80 mumol/L, 20.26%; 100 mumol/L, 20.17%; 120 mumol/L, 29.24%). AEA treatment increased pERK expression in both a concentration-dependent manner (AEA: 20 mumol/L, average gray value: 39.90+/-4.61; 60 mumol/L, 43.45+/-0.91; 120 mumol/L, 52.91+/-1.97; vs. negative control, all P less than 0.05) and a time-dependent manner (time: 15 min, average gray value: 85.05+/-15.80; 30 min, 103.41+/-11.89; 1 h, 118.02+/-12.24; 3 h, 109.17+/-15.69; 6 h, 100.86+/-10.55; 12 h, 71.70+/-12.87; 24 h, 34.62+/-14.85; 48 h, 22.84+/-11.73; vs. negative control, all except 48 h had P less than 0.05).

CONCLUSIONAEA can suppress the proliferative capacity of primary HSCs from schistosome-induced fibrotic livers through activation of the Erk signaling pathway.