The anaesthetic steroid alphaxalone positively modulates alpha1-glycine receptor function.

Inhibitory synaptic transmission within the dorsal horn of the spinal cord plays a key role in the processing of nociceptive signals, and mainly involves glycine. We have studied the effects of alphaxalone on alpha(1) homomeric glycine receptors expressed in a mammalian expression system (HEK 293 cells) using the whole-cell patch-clamp technique. Our experiments showed a coactivating effect of alphaxalone with a concentration for half-maximum activation (EC(50)) of the effect of a low glycine concentration (EC(20)) of 70.9 +/- 21.5 micromol/l. Taking into account the results of other groups, our study suggests that neuroactive steroids might be an interesting class of compounds to probe subunit-specific effects of glycine receptors.