Introduction: Pain as a complex process in the CNS has been extensively studied by many researchers. It has been
found that pain is controlled by certain pathways in the CNS, one of most important of which is the descending
noradrenergic system. The pathway begins with Locus Coeruleus (LC) nucleus and ends in the spinal cord. In this
study, formalin test was used as a chemical and tonic pain...
