[Effects of insulin-like growth factor 1 on inhibition of osteoblastic proliferation and function by ethanol]

To investigate the effects of insulin-like growth factor 1(IGF-1) and ethanol (EtOH) on the changes in the osteoblast proliferation and the osteoblast function under the normal serum concentration and serum starvation.

The osteoblasts harvested from the SD rat calvaria were incubated in the following six conditions according to the supplements in DMEM: the F15 group: 15% newborn calf serum (NCS); the Fis/EtOH group:100 mmol/L of EtOH added to 15% NCS; the F2 group: 2% NCS; the FZ/EtOH group: 100 mmol/L of EtOH added to 2% NCS;the F2/IGF-1 group:25 ng/ml of IGF-1 added to 2% NCS;the F2/IGF-1/EtOH group: 100 mmol/L EtOH added to 25 ng/ml IGF-1 and 2% NCS. The osteoblasts were analyzed by the MTT assay, alkaline phosphatase (ALP) activity, and RT-PCR at 24, 48, 72 and 96 hours after the culture.

The absorbance (A), the ALP activity, and the expression of BGP mRNA (the proliferation and function indicators of the osteoblasts) were significantly decreased in the F15/EtOH group at all the time points when compared with those in the F15 the group (P < 0.05); the above 3 indicators were significantly decreased in the F2 group when compared with those in the F15 group (P < 0.05); they were significantly decreased in the F2/EtOH group when compared with those in the F2 group (P < 0.05); however, the indicators in the F2/IGF-1 group were significantly increased when compared with those in the F2 group (P < 0.05); the A value in the F2/IGF-1/EtOH group was not significantly decreased when compared with that in the F2/IGF-1 group, with an exception of the A value at 24 hours (P > 0.05); however, ALP and BGP mRNA were significantly decreased (P < 0.05). All the indicators were significantly increased when compared with those in the F2/ EtOH group (P < 0.05).

Ethanol can inhibit the osteoblast proliferation and the osteoblast function, and can increase the inhibition when the osteoblasts were cultured under the serum starvation. This may be one of the mechanisms for alcoholic bone disease. IGF-1 can prevent the inhibition of the osteoblasts under the serum starvation and counteract the ethanol-induced proliferation inhibition; therefore, IGF-1 is an alternative therapeutic intervention for alcoholic bone disease.