Pain responses are modulated by GABAergic (inhibitory) and glutamatergic(excitatory) neurons in the spinal cord dorsal horn - too many glutamatergic neurons and even minor injuries are very painful. GABAergic and glutamatergic neurons are alternative fate choices in the developing neural dorsal tube, and now, Glasgow and colleagues report that the basic helix-loop-helix transcription factor Ptf1a directs developing neurons in the mouse dorsal horn towards a GABAergic fate (see ). The researchers show that Ptf1a is expressed in the precursors of GABAergic dorsal horn neurons, and report that, in mouse embryos that lack Ptf1a activity, the GABAergic neurons are mis-specified, resulting in an increase in glutamatergic neurons. The researchers conclude that Ptf1a contributes to the transcription factor code that specifies spinal cord neurons by having a selector function opposite to that of the homeodomain genes Tlx1 and Tlx3, which specify glutamatergic neurons.
