Axon terminals possessing the alpha 2c-adrenergic receptor in the rat dorsal horn are predominantly excitatory.

In this study we used confocal microscopy to show that most (83.67%) alpha(2C)-adrenergic receptor (alpha(2C)-AR)-immunoreactive terminals in the superficial dorsal horn contain the vesicular glutamate transporter 2 and hence are glutamatergic. Few (11.33%) terminals contain glutamic acid decarboxylase (a marker for GABAergic axons) and none were associated with the B subunit of cholera toxin (a marker for myelinated primary afferents) or the vesicular glutamate transporter 1. These data indicate that most dorsal horn axons possessing the alpha(2C)-AR are excitatory and add further support to the suggestion that they originate principally from spinal interneurons.