Effects of tumor necrosis factor alpha on taurine uptake in cultured rat astrocytes

Taurine is known to play a major role in volume regulation in astrocytic swelling associated with stroke and brain trauma. Apart from brain edema, the severity of brain injury is related to the levels of inflammatory cytokines such as tumor necrosis factor alpha (TNF alpha). TNF alpha had been shown to be closely associated with brain edema formation since the neutralization of TNF alpha reduced brain edema. Considering taurine has osmoregulatory functions in astrocytes, experiments were performed to study the effects of TNF alpha on taurine uptake in cultured astrocytes. Astrocytes exposed to 20 ng/ml of TNF alpha for 48 h showed a 91% increase in taurine uptake and significant increase was observed after 24 h exposure. This cytokine caused neither significant changes in cell volume nor taurine release. The increased in taurine uptake induced by TNF alpha was unlikely resulted from the modification of Na+. movement because TNF alpha decreased tyrosine uptake, Na+-dependent transport system. In contrast to TNF alpha, interferon-gamma (IFN gamma) did not significantly affect taurine uptake. Taken together, our results did not support a suggestion that TNF alpha affects cell volume regulation via modulating taurine uptake in astrocytes. Increasing lines of evidence have demonstrated that taurine has anti-inflammatory and anti-oxidative effects, these findings therefore suggested that the increase in taurine uptake might be an adaptive response or a tool for astrocytes against oxidative stress. (C) 2001 Elsevier Science Ltd. All rights reserved.