Effect of Medium Osmolarity and Taurine on Neuritic Outgrowth from Goldfish Retinal Explants
Taurine stimulates outgrowth of goldfish retinal explants in a concentration- and time-dependent manner, an effect related to calcium movement and protein phosphorylation. Since taurine is an osmoregulator in the central nervous system, and osmolality might influence regeneration, the purpose of this work was to evaluate the possible effect of hypo-osmolality on basal outgrowth and on the trophic action of the amino acid. Accordingly, goldfish retinal explants obtained after crushing the optic nerve were cultured in iso- and hypo-osmotic medium, the latter achieved by diluting the medium 10% 24 and 72 h after plating. The length and density of the neurites, measured after 5 days in culture, were significantly lwer in the hypo- than in the iso-osmotic medium. Taurine stimulated the outgrowth under both conditions, but the percentage of increase was greater in iso-osmotic medium. Taurine concentration, determined by HPLC, did not significantly change in explants. Co-administration of β-alanine and taurine impaired the trophic effect of taurine to a greater extent in the iso- than in hypo-osmotic medium, indicating a possible differential interaction with the taurine transporter which could be altered by osmotic stress. The exact mechanism of outgrowth regulation by hypotonicity requires further clarification, taking into considering possible modification of the taurine
KeywordsNeuritic Outgrowth Organic Osmolytes Human Intestinal Epithelial Cell Taurine Transporter Taurine Concentration
Unable to display preview. Download preview PDF.
- Bridi M, Choay P (2003) Taurine: a particular amionoacid with multiple functions. Ann Pharm Fr 61:385–391Google Scholar
- Caprini M, Gomis A, Cabedo H, Planells-Cases R, Belmonte C, Viana F, Ferrer-Montiel A M, Gomis A, Cabedo H, Planells-Cases R, Belmonte C, Viana F, Ferrer-Montiel A (2003) GAP43 stimulates inositol trisphosphate-mediated calcium release in response to hypotonicity. EMBO J 22:3004–3014PubMedCrossRefGoogle Scholar
- Morimura H, Shimada S, Otori Y, Saishin Y, Yamauchi A, Minami Y, Inoue K, Ishimoto I, Tano Y, Tohyama M (1997) The differential osmoregulation and localization of taurine transporter mRNA and Na+/myo-inositol cotransporter mRNA in rat eyes. Brain Res Mol Brain Res 44:245–252PubMedCrossRefGoogle Scholar