Figure 1.

Taurine-mediated neuroprotection against glutamate-induced retinal cell death.

Taurine activates both ionotropic taurine receptor (iTauR) and metabotropic taurine receptor (mTauR). Activated iTauR inhibits ability for the Na⁺/Ca²⁺ exchanger to reverse and block voltage-gated calcium channels (VGCC). Both events lead to decrease in intracellular calcium concentration. Activation of mTauR by taurine inhibits phospholipase C (PLC) activity, resulting in reductions in inositol triphosphate (IP₃) formation and hence IP₃-mediated release of Ca²⁺ from the internal pools. As a result, taurine inhibits glutamate-induced activation of calpain (a Ca²⁺-dependent enzyme), decreases heterodimerization of Bcl-2 and Bax, inhibits cytochrome C release, and prevents caspase-3 activation. Taurine also counteracts glutamate-mediated excitotoxicity by enhancing GABA transmission. Additionally, taurine exhibits a significant scavenging potential against peroxyl radicals, nitric oxide, and superoxide donors. Diagram was constructed based on concepts described by Wu and Prentice (2010), Oliveira et al. (2010) and Jakaria et al. (2019).