Exogenous glutamate and taurine exert differential actions on light-induced release of two endogenous amino acids in isolated rat retina

Taurine: A Source and Application for the Relief of Visual Fatigue

According to reports, supplementation with appropriate doses of taurine may help to reduce visual fatigue. Presently, some progress has been made in research related to taurine in eye health, but the lack of systematic summaries has led to the neglect of its application in the relief of visual fatigue. This paper, therefore, provides a systematic review of the sources of taurine, including the endogenous metabolic and exogenous dietary pathways, as well as a detailed review of the distribution and production of exogenous taurine. The physiological mechanisms underlying the production of visual fatigue are summarized and the research progress of taurine in relieving visual fatigue is reviewed, including the safety of consumption and the mechanism of action in relieving visual fatigue, in order to provide some reference basis and inspiration for the development and application of taurine in functional foods for relieving visual fatigue.

Effect of A(2A) receptor antagonist (SCH 442416) on the mRNA expression of glutamate aspartate transporter and glutamine synthetase in rat retinal Müller cells under hypoxic conditions in vitro

The purpose of the present study was to investigate the effect of the A(2A) receptor antagonist (SCH 442416) on the mRNA expression of glutamate aspartate transporter (GLAST) and glutamine synthetase (GS) in rat retinal Müller cells under hypoxic conditions in vitro. Immunofluorescent staining of GS and GFAP was used for the identification of Müller cells. The GLAST and GS mRNA expression of Müller cells treated with 0.1, 1 and 10 μM SCH 442416 under hypoxic conditions was examined by real-time PCR. Müller cells increased the mRNA expression of GLAST under hypoxic conditions; those treated with 0.1 μM SCH 442416 showed a further significant increase in the mRNA expression of GLAST in vitro. Although the mRNA expression of GS was decreased under hypoxic conditions, the mRNA expression was increased when Müller cells were treated with 0.1 μM SCH 442416. A(2A) receptor antagonist increased the GLAST and GS expression of Müller cells and accelerated the clearance of extracellular glutamate under hypoxic conditions in vitro.

Transporter mediated GABA release in the retina: Role of excitatory amino acids and dopamine

In general, the release of neurotransmitters in the central nervous system is accomplished by a calcium-dependent process which constitutes a common feature of exocytosis, a conserved mechanism for transmitter release in all species. However, neurotransmitters can also be released by the reversal of their transporters. In the retina, a large portion of GABA is released by this mechanism, which is under the control of neuroactive agents, such as excitatory amino acids and dopamine. In this review, we will focus on the transporter mediated GABA release and the role played by excitatory amino acids and dopamine in this process. First, we will discuss the works that used radiolabeled GABA to study the outflow of the neurotransmitter and then the works that took into consideration the endogenous pool of GABA and the topography of GABAergic circuits influenced by excitatory amino acids and dopamine.