Ethanol-induced sleep time: interaction with taurine and a taurine antagonist

In male Swiss-Webster mice sleep time (hypnosis) was used as an index of ethanol-induced central nervous system depression. Ethanol (4 g/kg, IP) was administered to animals and the onset to sleep time (loss of the righting reflex) and the duration of sleep time were recorded. At the end of the ethanol-induced sleep time, taurine (7.5, 15 or 25 mumol/kg, ICV) was injected. Immediately after the ICV injection of taurine the mice again lost the righting reflex. This effect of taurine occurred in a dose-dependent fashion. In the absence of ethanol, taurine (25 mumol/kg, ICV) did not produce a significant sleep time. In another experiment when TAG, 6-amino-methyl-3-4H-1,3,4-benzothiadiazine-1,1-dioxide HCl, (a taurine antagonist) was given to mice, TAG (0.9 mumol/kg, ICV) significantly reduced the effect of taurine (7.5, 15 and 25 mumol/kg, ICV) to reinstate a sleep time in the presence of ethanol. TAG, however, did not alter ethanol-induced sleep time. These results indicate that taurine (ICV) can enhance the central depressant action of ethanol and that this effect of taurine can be attenuated by TAG. The antagonism of taurine by TAG appears to be noncompetitive in nature.