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 sw elling associated with stroke and brain trauma. Apart from brain edema, the severity of brain injury is related to the levels of inflammatory cytokine s such as tumor necrosis factor alpha (TNF alpha). TNF alpha had been shown to be closely associated with brain edema formation since the neutralizati on of TNF alpha reduced brain edema. Considering taurine has osmoregulatory functions in astrocytes, experiments were performed to study the effects o f 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 cause d neither significant changes in cell volume nor taurine release. The incre ased 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, ou r results did not support a suggestion that TNF alpha affects cell volume r egulation via modulating taurine uptake in astrocytes. Increasing lines of evidence have demonstrated that taurine has anti-inflammatory and anti-oxid ative effects, these findings therefore suggested that the increase in taur ine uptake might be an adaptive response or a tool for astrocytes against o xidative stress. (C) 2001 Elsevier Science Ltd. All rights reserved.