Neuritic outgrowth from goldfish retinal explants, interaction of taurine and zinc

Various studies provide evidence for an interaction between taurine and zinc during development, affecting the morphology and function of the retina. The objectives of the present work were to determine taurine and zinc levels in the retina of goldfish during regeneration and to investigate the effect of the intracellular zinc chelator N,N,N,N-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) on the trophic role of taurine on outgrowth from post-crush goldfish retinal explants. Taurine was determined by HPLC (nmol/mg protein) and zinc by spectrophotometry ICP (microg/mg protein) at various days post-crushing the optic nerve. The levels of taurine were significantly increased at 72 h and the zinc levels at 24 h. Explants from retinas, 10 days post-crush, were cultured for 5 days in the presence of various concentrations and combinations of TPEN and taurine. TPEN, 1 nM, decreased the outgrowth but simultaneously with taurine (1-8 mM) there was an increase. These results demonstrate that zinc was necessary for normal outgrowth of retinal fibers and that taurine counteracted the chelator effect.