Taurine Effect on Stem Cells and Synaptogenesis Figure 4. Effects of taurine treatment on cell proliferation in the dentate gyrus of embryonic hippocampus. The embryonic brains were fixed at E-17. EdU intensity was measured for 6–7 identical sections per brain and at least 5–6 fetuses were used. The data of the percentage changes in EdU intensity are presented as mean 6 SEM. (A). Representative images showing EdU-labeled cells (red) in the dentate gyrus of control (left panel) and taurine treated groups (right panel) (B). P.0.05, Scale bar = 20 mm. doi:10.1371/journal.pone.0042935.g004 Some studies have shown that taurine influences neurotrans- mission [22]. Our results are in agreement with this notion as taurine can influence the neuronal maturation and synaptogenesis. Taurine has moderate effects on the number and length of neurite branches in primary neurons as well as NPCs-derived neurons. Taurine supplementation increases the expression of presynaptic and postsynaptic proteins in cultured hippocampal primary neurons as well as in hippocampal slices. Synapsin 1, a family of neuron-specific phosphor-proteins associated with the membranes of synaptic vesicles, have been identified as a molecular component involved in synaptogenesis [38]. Taurine treatment in hippocampal neurons significantly increased the number of synapsin 1 puncta (synapsins associated with synaptic vesicles) and synapsin 1 protein expression level, which is indicative of improved synaptogenesis. The postsynaptic density–95 (PSD-95) is a dendritic membrane-associated protein and may participate in synapse development, because it clusters at synapses before other postsynaptic proteins [39]. Husseini et al. [40], found that over expression of PSD-95 in hippocampal neurons can drive maturation of glutamatergic synapses. They also reported that postsynaptic expression of PSD-95 enhances maturation of the presynaptic terminal. Increased PSD-95 expression also increases the number and size of dendritic spines. These results demonstrate that increased PSD-95 levels in taurine treated neurons can orchestrate synaptic development and are suggestive of roles for taurine in synapse stabilization and plasticity. Our data support the notion that taurine is necessary for normal growth, development and maturation of neurons. It is well established that the levels of learning and memory are associated with the levels of neurogenesis and the number and complexity of dendrites. Taurine also shows moderate effect on dendrite growth and increase synaptogenesis. These studies explain the importance of taurine on maturation of the neurons. Together, these findings suggest possible effects of taurine in different stages of brain development, playing the role of a factor necessary for optimal maturation of brain cells. Taurine is present at high levels in the retina of many vertebrates [41]. Taurine is known to be involved in the mediation of multiple functions, such as osmoregulation, modulation of calcium fluxes, neuromodulation, protection from oxidative stress, modification of protein phosphorylation, mem- brane stabilization, affectation of cell migration in the brain and in the retina, regulation of axonal outgrowth, elevation in the number of regenerating retinal cells after nerve lesion [42]. Here, we showed an important role of taurine in increasing neural progenitor cell proliferation and neuronal maturation in the developing brain, which explains the importance of high taurine levels in the developing brain compared to adult brain [18,43]. These results indicate that taurine is an important nutritional PLOS ONE | www.plosone.org 6 August 2012 | Volume 7 | Issue 8 | e42935