Cholecystokininergic (CCK) and dopaminergic systems in the midbrain have been implicated in pain modulation. In the present study, Fos immunoreactivity was used as a marker of neuronal activity to investigate if subcutaneous injection of formalin (a model of noxious stimulation) could activate the CCKergic and dopaminergic neurons in the midbrain. Noxious stimulation increased significantly the numbers of Fos-positive CCKergic and dopaminergic neurons in the ventral tegmental area (VTA), whereas no significant changes in the numbers of Fos-positive CCKerigc or dopaminergic neurons were observed in other midbrain nuclei. These results indicate that the VTA may play a role in pain modulation.
- Noxious stimulation
- Ventral tegmental area
- c-fos protooncogene
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience