Medium requirements for neuritic outgrowth from goldfish retinal explants and the trophic effect of taurine.

The use of culture media of known composition are necessary for studying the role of trophic molecules. Since most of the in vitro research on regeneration of the optic nerve has been performed in the presence of fetal calf serum, the aim of this study was to obtain a medium in which the neuritic outgrowth from post-crush goldfish retinal explants could take place without adding fetal calf serum. After the lesion of the optic nerve (10 days), the retina of goldfish was dissected and explants were cultured for 5 and 10 days in the absence or in the presence of fetal calf serum, at which time the neuritic outgrowth was determined. Various concentrations and combinations of glucose, albumin, calcium, HEPES and taurine were used. The highest neuritic outgrowth was observed in the presence of fetal calf serum, in which condition the amino acid taurine increased length and density of neurites. Media supplemented with albumin, calcium or HEPES did not modify the outgrowth of neurites from the explants. However, glucose favored the neuritic outgrowth in a bell-shaped manner, although fibers were thinner than those observed in the presence of fetal calf serum. Taurine did not stimulate outgrowth of neurites from explants growing in a medium with optimal concentrations of glucose, indicating that elements of the fetal calf serum are determinant for the trophic effect of taurine. The present results contribute to further studies, such as those related to the effect of taurine and of trophic factors derived from the optic tectum, which would be performed in the presence of a medium free of fetal calf serum.