DEVELOPMENTAL-CHANGES OF GROWTH CONE GANGLIOSIDES OF THE POSTNATAL RAT CEREBRUM

THE ganglioside content and composition of growth cones prepared from forebrains of day 0 (p0), day 2 (p2), and day 6 (p6) postnatal rats wa s analysed in comparison with that of whole forebrain membranes obtain ed from rats of the same age. The amount of total ganglioside bound si alic acid (mug NeuAc mg protein-1) was found to increase in both whole cerebrum membranes and growth cones from p0 to p6. The ganglioside co ncentrations of growth cones exceeded that of the whole cerebrum by 35 -40% at all time points investigated. The major rat brain gangliosides were also found in the growth cone fractions, however, in different r elative amounts. Thus, the well known developmental shift from the b- to the a-ganglioside synthesis pathway was significantly delayed in gr owth cones, indicating that this shift is not associated with axonal g rowth but more likely with the subsequent period of synaptogenesis. GQ 1c, recognized by the mAb Q211, and an unidentified growth-cone specif ic ganglioside x were found to be expressed in growth cones of po rats and to decrease up to p6.