Michelle A. Tucci
University of Mississippi Medical Center, USA
Painful neuromas are a common and debilitating result of peripheral nerve trauma and a common complication following limb amputation. We sought to evaluate early developing and mature neuromas tissue for specific subtypes of fibers and receptors based on their immuno-reactive profiles. Our overall goal was to identify the location of the NPY producing cells and the density of NPY 1 receptor on the growing neuroma tissue. Neuropeptide Y is a 36 amino acid peptide that has been implicated in pain and the NPY 1 receptor is believed to contribute to the growth of the neuroma. The results show by 30 days the presence of a neuroma that increased in size over 60 days. Within seven days of injury the pain withdrawal threshold declined by 73% while an average decline in the Sham injured animal group declined 33%. The decline in the Sham group was most likely due to inflammatory pain from the surgical site. By 30 days the animals in the Sham group showed no differences in pain threshold measurements either between legs or compared to the control Naïve animals. The CCI animals showed a slight rebound in pain threshold withdrawal to 43% of their baseline score. Similar finding were seen at the 60 day time point. Detection of the NPY 1 receptor was seen surrounding the epineurium and the cells positive for NPY were within the fat surrounding the nerve and with the cells of perineum. Overall, our findings show NPY producing cells in the expanding region of the neuroma. Future research will be directed at targeting the receptors to disrupt growth and/or development of the neuroma.