Development modulates the serum induced effect on the incorporation of [2-3H]mannose into chick optic lobe protein: the possible role of glia.

Recently, we described that serum decreases tritiated mannose incorporation into protein in the chick optic lobe at 18 days of embryonic age (Rossi et al., 1990). In this paper, we found a strikingly different response of this serum effect according to age. The data obtained showed no serum induced decrease in 6-10-day-old embryo. In addition, our results demonstrate that the differential response of the tissue to the serum is independent of the rate of sugar entry into nerve cells. Furthermore, we also report that the variation of mannose or leucine incorporation into protein coincides very closely with the pattern of protein and glycoprotein accumulation during chick optic lobe development. Finally, data were obtained to define glial cells as the cellular target of the serum induced effect. This finding may contribute to elucidate the mechanism of cellular pathogenesis of cerebral lesions that occur after the breakdown of the blood brain barrier, such as in some diseases or during bleeding after injuries.