The Effects of Estradiol Treatment on Synaptic Reorganization and Plasticity Around Motoneurons After Traumatic Peripheral Nerve Injury in Mice.

Student: Vernon Kennedy Jr

Major: Molecular Biology

Mentors: Dr. Jennifer Wilhelm

Department: Psychology

The Effects of Estradiol Treatment on Synaptic Reorganization and Plasticity Around Motoneurons After Traumatic Peripheral Nerve Injury in Mice.

Each year 100,000 Americans experience injuries to their nerves. Most of these patients don't fully recover and are left with various physical deficits. This inadequate healing often results from the negative changes that take place in the spinal cord after injury. Following peripheral nerve injury, many of the connections within the spinal cord can be lost or remodeled. These changes result in miscommunication between the spinal cord and muscles, leading to muscle spasms and muscle degeneration. Previous research suggests that exercise coupled with testosterone treatments can mitigate this reorganization. In this study, we explored whether estrogen could potentially have similar effects. Using a mouse model, we surgically injured the sciatic nerve of the right hind limb. Injured nerves were marked with a fluorescent dye and the animals were treated with various combinations of estrogen, exercise and an estrogen receptor blocking agent. Following this period, tissue samples from the spinal cord were harvested and sliced into sections. Spinal cord sections were stained for certain connections and changes in these connections were observed via fluorescent microscopy. Preliminary results show a decrease in the reorganization of connections after estrogen treatments are applied compared to untreated animals. We also observed that preventing estrogen signaling during exercise eliminates the positive effects of exercise therapy. These findings are significant because they suggest that estrogen signaling is essential for exercise-dependent recovery methods. Further illuminating the relationship between sex hormones and the recovery of injured nerves can potentially lead to effective therapeutic methods for humans.