CHARACTERISTIC EXPRESSION OF GD-1-ALPHA-GANGLIOSIDE DURING LACTATION IN MURINE MAMMARY-GLAND

Cellular proliferation and differentiation in mammary gland are known to be significantly altered during pregnancy and subsequent lactation, To characterize the different stages of mammary gland during pregnanc y and lactation, we analyzed the glycosphingolipid compositions in the mammary gland of DDD and ICR mice at several periods of pregnancy and lactation, and found that the ganglioside composition, but not neutra l glycosphingolipids, was characteristically altered during the pregna ncy and lactation periods. The concentrations of acidic glycosphingoli pids, (ISO3)-S-3-GalCer(1), GM3, GM1a, GM1b and GD1a, were reduced dur ing the course of pregnancy and lactation. GD1 alpha (III(6)NeuAc alph a,IV(3)NeuAc alpha-Gg(4)Cer) was first detected at the mid-period of p regnancy (12 days of pregnancy for ICR mice), increased in concentrati on at the late-period of pregnancy (GD1 alpha concentration was 100 ti mes higher at 18 days than that at 12 days of pregnancy), and was a ma jor ganglioside comprising 60-70% of the total lipid-bound sialic acid in the mammary gland of ICR and DDD mice at the lactation period, ind icating that expression of GD1 alpha is associated with the lactating mammary gland of mice, In fact, GD1 alpha was highly concentrated in t he milk fat globule, in which it was a major component.