Dopaminergic projections from the ventral tegmental area to the insula cortex contribute to neuropathic pain modulation

Ventral tegmental area(VTA),which is well-documented as a modulatory center of reward and addiction,has been demonstrated to participate in pain processing.In addition,insula cortex(IC)has also been proved to be related with maintenance of neuropathic pain.In the present study,in order to clarify whether there exist dopaminergic projections from the VTA to the IC,retrograde and anterograde tracing methods combined with immunofluorescent histochemical staining were applied.The results revealed that almost all VTA-IC-projecting neurons originated from the VTA were dopaminergic neurons,with smaller amount of GABAergic neurons sending projection fiberss to the IC.