Differential taurine effect on outgrowth from goldfish retinal ganglion cells after optic crush or axotomy. Influence of the optic tectum.

The interaction between innervated tissues, targets and nerves is crucial in the maintenance of physiological conditions, and the disturbance of this harmony causes the production of morphological and biochemical changes. After lesion of the optic nerve, several modifications take place in the retina, the optic tectum and the optic nerve. The influence of the tectum on the outgrowth from the goldfish retina and the possible role of taurine was studied. Ganglion retinal cells were identified by retrolabeling with Dil. Crushing the optic nerve 10 days prior to plating retinal cells, as compared with optic axotomy, did not affect the survival of cultured retinal cells, as well as the length of the neurites. However, the number of neurites per cell and the branching of the longest fiber were higher after axotomy than after crushing. The addition of taurine to the medium did not modify this response at 5 days in culture. At early periods in culture, the stimulatory effect on isolated ganglion cell outgrowth produced by taurine was enhanced after axotomy respecting crushing of the optic nerve, but was not affected in retinal explants. The addition of medium from cultured optic tectum several days post-crush of the optic nerve to retinal explants from intact retinas or coming from post-crush retina modified the outgrowth, being inhibitory or stimulatory in a time-dependent manner. The co-culture of optic tectum and retina also affected the outgrowth from the retina with a byphasic shape. The results support the differential response of the retina facing partial or complete interruption with the target and limit the effect of taurine to early periods in culture. In addition, the production of inhibitory factors from the tectum, plus the stimulatory ones, are strongly supported by this work.